Hazardous Air Pollutants

Introduction

This section includes pollutants singled out for control under recent international protocols extending the Convention on Long-range Transboundary Air Pollution- namely Persistent Organic Pollutants (POPs) and Heavy Metals (HMs).

UN/ECE Heavy Metals and POPs Protocols

The Convention on Long-range Transboundary Air Pollution was signed in 1979 and entered into force in 1983. Since its entry into force the Convention has been extended by a number of protocols, including the 1998 Protocol on Heavy Metals and the 1998 Protocol on POPs. These two Protocols are given in outline below; more information may be found at the UN/ECE web site, located at:- http://www.unece.org/env/lrtap/. The UK has signed both of these protocols but they have not yet been ratified by a sufficient number of countries to come into force.

Persistent Organic Pollutants (POPs)

The UN/ECE Protocol on Persistent Organic Pollutants focuses on a list of 16 substances (or groups of substances), which have been identified according to certain risk criteria. In brief, these 16 pollutants may be classified in three source sectors as follows:

1. Pesticides: aldrin, chlordane, chlordecone, DDT, dieldrin, endrin, heptachlor, hexachlorobenzene (HCB), mirex, toxaphene, hexachlorocyclohexane (HCH) (incl. lindane);

2. Industrial Chemicals: hexabromobiphenyl, polychlorinated biphenyls (PCBs);

3. By-products or Contaminants: dioxins, furans, polycyclic aromatic hydrocarbons (PAHs).

The ultimate objective of the protocol is to eliminate any losses, discharges and emissions of POPs to the environment. This is achieved through several different legislative mechanisms. First, the production and use of several compounds is banned (aldrin, chlordane, chlordecone, dieldrin, endrin, hexabromobiphenyl, mirex and toxaphene). Secondly, several compounds are scheduled for elimination at a later date (DDT, heptachlor, hexachlorobenzene, PCBs). Finally, the protocol severely restricts the use of selected compounds (DDT, HCH- including lindane and PCBs). Limited uses which are thought to be essential and for which there are no adequate substitutes, can be exempted. For instance, the use of substances like DDT would be allowed under the protocol for public health emergencies. The protocol includes provisions for dealing with the surplus of products that will be banned.

Under the protocol, countries are also required to reduce their emissions of dioxins, furans, PAHs and HCB below their levels in 1990 (or an alternative year between 1985 and 1995). The protocol requires the best available techniques (BAT) to be applied to cut emissions of these POPs. For the incineration of municipal, hazardous and medical waste, it lays down specific limit values. The protocol allows for the addition of further compounds into control, depending on the development of the scientific basis for such an action.

In 1999 EPAQS published a report on PAHs which recommended an Air Quality Standard of 0.25 ng m^-3 benzo[a]pyrene as an annual average. As a result, further work assessing the concentrations of PAHs in the atmosphere has been commissioned by Defra and the results compared with the spatially disaggregated emissions inventory.

In August 2002 PAHs were added to the list of pollutants covered by the Air Quality Strategy for England (see Chapter), and an objective was set relating to the PAH concentrations in the air. As a consequence there is a continued drive to decrease PAH emissions from the major sources.

Continued improvements have been made in compiling the 2000 UK emission estimates for POPs. This has been instigated in a response to the increasing interest in hazardous air pollutants and their impact on the environment over the last several years. The level of data available for many of these pollutants is relatively limited and hence several areas of the current emission inventory have been targeted for improvements which will be included in future emission estimates as a part of the NAEI continuous improvement process.

Table 6.1 lists the toxic pollutants (i.e. POPs and heavy metals) included in the current inventory together with their total UK emissions in 2000. Each of the pollutant classes are considered in more detail in the following sections.

Heavy Metals

The UN/ECE Protocol on Heavy Metals targets three particularly harmful substances: lead, cadmium and mercury. Countries are obliged to reduce their emissions of these three metals below their levels in 1990 (or an alternative year between 1985 and 1995). The protocol aims to cut emissions from industrial sources (iron and steel industry, non-ferrous metal industry), combustion processes (power generation, road transport) and waste incineration.

The protocol specifies limit values for emissions from stationary sources and requires BAT for obtaining emission reductions from these sources, such as special filters or scrubbers for combustion sources or mercury-free processes. The protocol also requires countries to phase out leaded petrol.

Under the protocol, measures are introduced to lower heavy metal emissions from other products e.g. mercury in batteries, and examples are given of management measures for other mercury-containing products, such as electrical components (thermostats, switches), measuring devices (thermometers, manometers, barometers), fluorescent lamps, dental amalgam, pesticides and paint.

Further metals may be added to the protocol, and further measures may be introduced for lead, cadmium and mercury, depending on the development of the scientific basis for action.

The best known effects of heavy metals are those on humans and animals. Of these, the most important effects are deterioration of the immune system, the metabolic system and the nervous system. They lead to disturbances in behaviour and some heavy metals are suspected to be or have been proven to be carcinogenic.

The impact of heavy metals on the environment due to long-range transport can be summarized as:

1. Impact on aquatic ecosystems. Atmospheric deposition of metals may influence the quality of surface waters and ground water. In addition to the effects on the uses of water (e.g. restricted use of water for human consumption, livestock, recreation etc) accumulation in aquatic organisms may have adverse effects on the food web.

2. Impact on terrestrial systems. Metal uptake by plants is a key route for the entry of metals into the food chain. Contaminants may be toxic to plants and can alter the structure or diversity of a habitat. When plants accumulate metals, these can be ingested by animals creating the potential for toxic effects at higher trophic levels.

3. Mesofauna and macrofauna. The accumulation of cadmium and lead in birds and mammals in remote areas is attributable to long range atmospheric transport.

4. Agricultural products. Airborne heavy metals account for significant fractions of the total heavy metal input to arable soils.

Major environmental problems due to long range transport have been reported, relating to the:

· Accumulation of Pb, Cd and Hg in forest top soils, implying disturbed nutrient recirculation in forest ecosystems and increased stress on tree vitality in central Europe, reinforced by the acidification of soils

· Highly increased content of Hg in fish from lakes, especially in Scandinavia.

Table 6.1 Total UK Emissions of Toxic Pollutants

Pollutant	Total 2000 UK emission
Persistent organic compounds (POPs) · Polycyclic aromatic hydrocarbons (PAHs)	2165	tonnes (USEPA16)
· Dioxins and Furans (PCDD/F)	347	TEQ grammes
· Polychlorinated biphenyls (PCBs)	1.71	tonnes
· Pesticides		tonnes
- lindane (g-HCH) - pentachlorophenol (PCP) - hexachlorobenzene (HCB)	32 476 0.79
· Short Chain Chlorinated Paraffins (SCCPs)	3	tonnes
· Polychlorinated Napthalenes (PCNs)	NE^1
· Polybrominated Diphenyl Ethers (PBDEs)	13.8	tonnes
Heavy metals		tonnes
· Arsenic	35
· Beryllium	16
· Cadmium	5.2
· Chromium	63
· Copper	46
· Lead	496
· Manganese	303
· Mercury	8.5
· Nickel	115
· Selenium	50
· Tin	74
· Vanadium	157
· Zinc	336

¹NE- Not Estimated. It has not been possible to make an emission estimate

Persistent organic pollutants

Persistent organic pollutants (POPs) are found in trace quantities in all areas of the environment. They accumulate in humans and plants, and have differing degrees of toxicity. POPs do not readily break down in the environment with half-lives in soils in the order of years, although they may be transformed both physically and chemically over long periods.

Over recent years there has been a growing interest in these pollutants and in particular their potential chronic toxicity and impacts on human health. This is reflected by the recent international agreement to reduce releases of these chemicals under the UN/ECE Persistent Organic Pollutants Protocol (detailed in Section 6.1) and their consideration for air quality standards by the Expert Panel on Air Quality Standards (EPAQS). The detailed methodology for the compilation of these inventories depends on the combination of emission factors gathered from a range of sources and production statistics used elsewhere in the emission inventory or developed for the specific sector concerned.

The UK NAEI does not include emission estimates for a number of POPs that have been banned in the UK for several years. Table 6.2 below indicates the years in which the use of particular POPs were banned or their use severely restricted, and whether the listed POPs are included in the NAEI.

Table 6.2 POPs Included/Not Included in the NAEI and Corresponding Year of Ban on Use

Compound or Compound Group	Banned in UK	Included in NAEI
Polycyclic aromatic hydrocarbons (PAHs)	-	Yes
Dioxins and Furans (PCDD/Fs)	-	Yes
Polychlorinated biphenyls (PCBs)	-	Yes
Hexabromobiphenyl	Never Used	No
Pesticides
g-Hexachlorocyclohexane	-	Yes
Pentachlorophenol^1	1995^2	Yes
Hexachlorobenzene^1	1975	Yes
Aldrin	1989	No
Chlordane	1992	No
Dichlorodiphenyl-trichloroethane (DDT)	1984	No
Chlordecone	1977	No
Dieldrin	1989	No
Endrin	1984	No
Heptachlor	1981	No
Mirex	Never Used	No
Toxaphene	Never Used	No

¹Hexachlorobenzene and pentachlorophenol are also emitted from other sources as well as being or having been active ingredients in pesticides.

² Use of pentachlorophenol is severely restricted rather than banned absolutely.

Polycyclic aromatic hydrocarbons (PAHs)

Polycyclic aromatic hydrocarbons are a large group of chemical compounds with a similar structure comprising two or more joined aromatic carbon rings. Different PAHs vary both in their chemical characteristics and in their environmental sources and they are found in the environment both as gases and associated with particulate material. They may be altered after absorption into the body into substances that are able to damage the genetic material in cells and initiate the development of cancer, although individual PAHs differ in their capacity to damage cells in this way.

The speciated PAH inventory was first compiled for the 1996 emissions inventory (see “Speciated PAH Inventory for the UK” Wenborn MJ 1999) and has allowed a more detailed understanding of the PAH emissions in the UK.

There have been several pollutant classifications relating to PAHs. Although there are a vast number of PAHs, the NAEI inventory focuses on sixteen. These 16 PAHs have been designated by the United States Environmental Protection Agency (USEPA) as compounds of interest under a suggested procedure for reporting test measurement results (USEPA 1988). The estimated emissions for individual compounds are given in Appendix 5 (for the appendices of this report see http://www.naei.org.uk/). A subset of this includes six of the PAHs identified by the International Agency for Research on Cancer (IARC) as probable or possible human carcinogens (IARC 1987). In addition, the Borneff 6 PAHs (another subset focussing on the health impacts of the PAHs) have been used in some EC emission inventory compilations. A further subset of PAHs are those to be used as indicators for the purposes of emissions inventories under the UN/ECE’s Persistent Organic Pollutants Protocol. These classifications are given in the following table.

Table 6.3 The USEPA 16 PAH Primary Pollutants, and other PAH Subsets.

	Included in the NAEI	USEPA Priority pollutants (16 PAH)	IARC Probable or possible Human carcinogens (6 PAH)	Borneff (6 PAH)	UN/ECE POPs Protocol Indicators for purpose of emission inventories
Naphthalene	ü	ü
Acenapthene	ü	ü
Acenapthylene	ü	ü
Fluorene	ü	ü
Anthracene	ü	ü
Phenanthrene	ü	ü
Fluoranthene	ü	ü		ü
Pyrene	ü	ü
Benz[a]anthracene	ü	ü	ü
Chrysene	ü	ü
Benzo[b]fluoranthene	ü	ü	ü	ü	ü
Benzo[k]fluoranthene	ü	ü	ü	ü	ü
Benzo[a]pyrene	ü	ü	ü	ü	ü
Dibenz[ah]anthracene	ü	ü	ü
Indeno[1,2,3-cd]pyrene	ü	ü	ü	ü	ü
Benzo[ghi]perylene	ü	ü		ü

The main environmental impact of PAHs relate to their health effects, focusing on their carcinogenic properties. The most potent carcinogens have been shown to be benzo[a]anthracene, benzo[a]pyrene and dibenz[ah]anthracene (APARG 1996). The semi‑volatile property of PAHs makes them highly mobile throughout the environment via deposition and re-volatilisation between air, soil and water bodies. It is possible that a proportion of PAHs released in the UK are deposited in the oceans and/or subject to long range transport making them a widespread environmental problem.

In 1999 the Expert Panel on Air Quality Standards (EPAQS) published a recommendation for an air quality standard for PAHs. This standard was based on the use of benzo[a]pyrene as an indicator of the overall carcinogenicity of the PAHs present in the atmosphere. In August 2002 PAHs were included in the Air Quality Strategy for England (see Section 4.1) through the introduction of an objective relating to concentrations in ambient air.

Emissions of benzo[a]pyrene (BaP) and the total of the 16 PAH’s are summarised in Table 6.4. Aluminium production and anode baking (carried out for the aluminium industry) was the largest source of PAH emissions in the UK up until 1996 (contributing nearly half of the total PAH emission). Emissions since then have declined and in 2000 these sources accounted for only 13% of the emissions. This is a consequence of investment in abatement equipment following from the authorisation regime implementing the Environmental Protection Act 1990. One of the anode baking plants has dramatically reduced its emissions and the other is timetabled to follow shortly.

Road transport combustion is currently the largest source of PAH emissions contributing 53% of the emissions in 2000. These figures have been substantially revised since the last NAEI Report. This is primarily a result of revisions to the emissions of napthalene from road transport combustion. Further detail on the methodology changes can be found in Appendix 1 (See http://www.naei.org.uk/). The next largest sources of emissions in 2000 were domestic combustion and non -ferrous metal production.

Emissions of PAH and BaP from domestic combustion increased between 1997 and 1999 but declined in 2000. This reflects the increased consumption of coal in the domestic sector during 1997 to 1999 and the subsequent decline in 2000.

There are several source sectors relevant to PAHs which have been targeted for improvement:

· Wood treatment may be a significant source of some of the lighter PAHs such as acenapthene, fluorene and anthracene. Currently this source is not included due to a lack of available data. However, data is being sought, and the feasibility of including emission estimates from this source will be determined.

· Emissions from bitumen production and use have not been estimated due to a lack of emission data. It is possible that bitumen use is a significant source of benzo[a]pyrene and other PAHs.

The BaP inventory has been updated to incorporate new information regarding emission factors and activity data on sources of BaP. The new estimates differ significantly from the last NAEI Report (Goodwin et al., 2000). Current total BaP emissions for 1999 are approximately 23% lower than those previously estimated for 1999.

The most notable changes to the BaP inventory are significantly reduced emissions from some industrial sources and smaller road transport emissions. Further detail can be found in Coleman et al., 2001.

Increased measurement of PAHs by both industry and regulators, particularly in the aluminium sector, has allowed improvements in the precision of the emission estimates. The uncertainties associated with the emissions estimates of PAHs are considered in Section 6.4.

Table 6.4 UK emissions of PAHs (Emissions of individual PAHs are given in Appendix 5- see http://www.naei.org.uk/)

Table 6.4a Emissions of 16 PAHs¹ (tonnes)

	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2000%
BY UN/ECE CATEGORY
Comb. in Energy Prod.
Public Power	6	6	5	4	4	4	4	3	4	3	3	0%
Petroleum Refining Plants	4	4	4	4	4	4	4	5	5	5	4	0%
Other Comb. & Trans.	10	10	7	4	2	1	1	1	1	1	1	0%
Comb. in Comm/Inst/Res
Residential Plant	765	786	760	739	591	464	485	471	488	523	411	18%
Comm/Pub/Agri Comb.	32	29	19	21	19	16	17	18	10	4	3	0%
Combustion in Industry
Iron & Steel Comb.	24	23	23	22	23	23	23	23	23	23	19	1%
Other Ind. Comb.	394	434	521	422	407	381	317	236	148	156	85	4%
Production Processes
Non-Ferrous Metals	3490	3354	3219	3083	2947	2307	735	432	394	277	276	12%
Processes in Industry	107	99	91	86	87	87	87	87	86	82	83	4%
Solvent Use	104	100	97	94	90	87	83	80	76	73	69	3%
Road Transport
Combustion	2315	2274	2169	2110	2082	1900	1776	1627	1412	1294	1141	50%
Other Trans/Mach	9	9	9	9	8	6	6	5	4	4	4	0%
Waste	66	66	66	66	66	66	66	65	65	65	65	3%
Agriculture	933	800	582	12	0	0	0	0	0	0	0	0%
Nature (Natural Fires)	95	95	95	95	95	95	95	95	95	95	95	4%
TOTAL	8353	8090	7667	6770	6425	5441	3697	3146	2810	2604	2259	100%

Table 6.4b Emissions of BaP² (tonnes)

	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2000%
BY UN/ECE CATEGORY
Comb. in Energy Prod.
Public Power	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Petroleum Refining Plants	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Public Power (waste incin)	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Other Comb. & Trans.	0.1	0.1	0.1	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Comb. in Comm/Inst/Res
Residential Plant	6.1	6.3	6.0	5.8	4.5	3.4	3.6	3.4	3.6	3.9	2.9	27%
Comm/Pub/Agri Comb.	0.3	0.2	0.2	0.2	0.2	0.1	0.1	0.2	0.1	0.0	0.0	0%
Combustion in Industry
Iron & Steel Comb.	0.1	0.1	0.0	0.0	0.1	0.0	0.0	0.0	0.0	0.1	0.0	0%
Other Ind. Comb.	0.0	0.0	0.1	0.1	0.1	0.0	0.0	0.0	0.0	0.0	0.0	0%
Production Processes
Non-Ferrous Metals	24.6	23.7	22.7	21.8	20.8	16.3	5.2	3.9	3.0	2.1	2.0	19%
Processes in Industry	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.1	1%
Solvent Use	0.1	0.1	0.1	0.1	0.1	0.1	0.0	0.0	0.0	0.0	0.0	0%
Road Transport
Combustion	5.3	4.6	3.9	3.2	2.7	2.1	1.7	1.3	1.0	0.8	0.7	6%
Other Trans/Mach	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.0	0.0	0.0	0.0	0%
Waste	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0	18%
Agriculture	28.3	24.3	17.7	0.4	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Nature	2.9	2.9	2.9	2.9	2.9	2.9	2.9	2.9	2.9	2.9	2.9	27%
TOTAL	70	65	56	37	33	27	16	14	13	12	11	100%

¹ The PAHs selected are listed above in Table 6.3

² Benzo[a]pyrene

Figure 6.1 UK Emissions of 16 PAHs (tonnes)

Figure 6.2 UK Emissions of Benzo[a]Pyrene (tonnes)

Figure 6.3 Spatially Disaggregated UK Emissions of Benzo[a]pyrene

Dioxins and Furans (PCDD/F)

The term “dioxin” is used to refer to the polychlorinated dibenzo-p-dioxins (PCDD) and “furan” is used for polychlorinated dibenzofurans (PCDF). There are 210 PCDD/F compounds in total, which can be described as "congeners"- i.e. different compounds within a family or group having a similar structure. Of these 210 compounds the emissions of importance are those of the 17 PCDD/Fs (7 PCDDs and 10 PCDFs) as defined by the NATO/CCMS (Committee on the Challenges of Modern Society 1988) international toxic equivalent (I-TEQ) scheme. TEQ schemes weight the toxicity of the less toxic congeners as fractions of the toxicity of 2,3,7,8-TCDD, the most toxic congener.

The inventory presented here is in terms of the sum of the weighted emissions expressed as ‘I-TEQs’ which are widely used in UK and European legislation. However, more recently the World Health Organisation (WHO) has suggested a modification to the values used to calculate the toxic equivalents for some of the PCDDs and PCDFs. They have also suggested that there is value in using a similar approach for the PCBs which have dioxin-like toxicity and combining the PCDD/F and PCB TEQs together. The International and the WHO toxic equivalence factors (TEFs) for PCDD/Fs are shown in Table 6.5

Table 6.5 The International and the WHO Toxic Equivalence Factors for PCDD/Fs

(the differences are highlighted)

Dioxins	International TEFs	WHO TEFs
2,3,7,8 tetraetrachlorodibenzo-p-dioxin	1	1
1,2,3,7,8 pentachlorodibenzo-p-dioxin	0.5	1
1,2,3,4,7,8 hexachlorodibenzo-p-dioxin	0.1	0.1
1,2,3,6,7,8 hexachlorodibenzo-p-dioxin	0.1	0.1
1,2,3,7,8,9 hexachlorodibenzo-p-dioxin	0.1	0.1
1,2,3,4,6,7,8 heptachlorodibenzo-p-dioxin	0.01	0.01
Octachlorodibenzo-p-dioxin	0.001	0.0001
Furans
2,3,7,8 tetra4chlorodibenzofuran	0.1	0.1
1,2,3,7,8 pentachlorodibenzofuran	0.05	0.05
2,3,4,7,8 pentachlorodibenzofuran	0.5	0.5
1,2,3,4,7,8 hexachlorodibenzofuran	0.1	0.1
1,2,3,6,7,8 hexachlorodibenzofuran	0.1	0.1
1,2,3,7,8,9 hexachlorodibenzofuran	0.1	0.1
2,3,4,6,7,8 hexachlorodibenzofuran	0.1	0.1
1,2,3,4,6,7,8 heptachlorodibenzofuran	0.01	0.01
1,2,3,4,7,8,9 heptachlorodibenzofuran	0.01	0.01
Octachlorodibenzofuran	0.001	0.0001

¹ NATO/CCMS (1988) ² WHO (1998)

PCDD/Fs have been shown to possess a number of toxicological properties. The major concern is centred on their possible role in immunological and reproductive effects. The main sources of PCDD/Fs are thermal processes, but they can also be released to the environment from some chemical processes.

PCDD/Fs can arise from any thermal process where chlorine is present. For example, coal and other solid fuels contain trace amounts of chlorine compounds which can under certain combustion conditions result in PCDD/F formation. In addition PCDD/Fs can be present in the feed stock material, or chlorinated impurities may be introduced into the feed stock of some thermal processes. The amount of chlorine required for PCDD/F formation may be small and consequently many processes have the potential to emit these pollutants. PCDD/Fs can also be emitted from the chemical production and use of polychlorinated aromatic pesticides and herbicides, many of which are now controlled. However, some chlorinated organic chemicals such as the wood preservative pentachlorophenol are still used in the UK and these have the potential to be sources of PCDD/Fs e.g. from the combustion of treated wood.

Estimated PCDD/F emissions for 1990-2000 are summarised in Table 6.6 below.

Table 6.6 UK emissions of PCDD/Fs (grams TEQ/year)

	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2000%
BY UN/ECE CATEGORY
Comb. in Energy Prod.
Public Power	137	137	157	200	267	223	120	63	23	19	14	4%
Petroleum Refining Plants	12	13	13	14	14	14	14	14	14	12	9	3%
Other Comb. & Trans.	0	0	0	0	0	0	0	0	0	0	0	0%
Comb. in Comm/Inst/Res
Residential Plant	74	75	73	74	71	67	68	66	66	67	65	18%
Comm/Pub/Agri Comb.	98	100	91	80	71	56	43	33	24	24	21	6%
Combustion in Industry
Iron & Steel Comb.	50	49	48	48	48	48	48	49	47	45	41	11%
Non-Ferrous Metals	22	19	17	19	18	18	19	18	17	18	14	4%
Other Ind. Comb.	63	65	67	64	69	65	63	59	54	56	47	13%
Production Processes
Iron & Steel	31	26	28	29	29	30	28	30	26	17	17	5%
Non-Ferrous Metals	6	6	5	5	5	5	5	5	5	5	6	2%
Processes in Industry	6	5	5	4	4	4	4	3	3	3	3	1%
Solvent Use	0	0	0	0	0	0	0	0	0	0	0	0%
Road Transport
Combustion	29	26	23	20	18	16	14	11	8	6	5	1%
Vehicle Fires	6	6	6	6	6	7	7	7	7	7	7	2%
Other Trans/Mach	1	1	1	1	1	1	1	1	1	0	0	0%
Waste
Landfill	1	1	1	1	1	1	1	1	1	1	1	0%
Waste Incineration	586	580	561	517	370	307	195	99	103	104	104	29%
Other Waste Treat. & Disp.	0	0	0	0	0	0	0	0	0	0	0	0%
Agriculture	57	49	36	1	0	0	0	0	0	0	0	0%
Nature	6	6	6	6	6	6	6	6	6	6	6	2%
TOTAL	1184	1164	1138	1089	999	869	637	466	406	390	360	100%

The largest sources of PCDD/F emission has bee, and still is, waste incineration. However emissions from waste incineration have fallen rapidly from 1993 to 2000. This significant trend has been driven by the introduction of control measures. MSW incinerators not meeting the new standards closed in the period leading up to December 1996. New designs of MSW incinerator result in significantly lower levels of PCDD/F emissions.

The relatively low emissions from chemical incinerators reflects the use of rotary kilns and the incorporation of a secondary combustion chamber in the process to destroy organic contaminants together with the relatively low waste throughput and advanced pollution abatement equipment. However, clinical waste incineration remains a significant source. This is due to the fact that emissions from clinical waste incinerators (although showing significant reductions) have not been reducing as rapidly as the total PCDD/F total.

Figure 6.4 UK Emissions of PCDD/Fs (grammes TEQ)

Emissions from power stations are fairly low because the combustion is efficient and the post‑combustion fly ash temperatures are rapidly reduced. The emission factors associated with industrial and domestic coal combustion are significantly higher and sum to give a similar contribution, even though the coal consumption is less. However, emissions from all three sectors have decreased with the reduction in the quantity of coal burned.

Emissions from open agricultural burning and accidental fires are included in the agricultural and nature sectors. The former has declined to near zero since the cessation of most agricultural burning. Accidental fires are currently treated as a source of constant magnitude, and consequently, the percentage contribution from this sector to the total PCDD/F emission has risen as emissions from other significant sectors have decreased.

There are significant emissions from sinter plants owing more to the large gas volumes emitted than to high concentrations. Emissions from iron and steel plants are probably underestimated since only electric arc furnaces are considered. Scrap used in electric arc furnaces and secondary non-ferrous metal production will contain chlorinated impurities such as plastics and cutting oil which contribute to PCDD/F formation.

It is generally accepted that the source of PCDD/F emissions from road transport are the 1,2-dichloroethane scavengers added to leaded petrol. Over recent years both the consumption of leaded petrol, and the lead content of leaded petrol has decreased. Consequently the emissions of PCDD/F from this sector have decreased. Unleaded petrol and diesel is likely to contain only trace quantities of chlorinated impurities. For 2000, the contribution to the PCDD/F emission total from road transport was 1%.


Figure 6.5 Spatially Disaggregated UK Emissions of PCDD/F

Polychlorinated biphenyls (PCBs)

PCBs are synthetic organic compounds that have mainly been used in electrical equipment as dielectric insulating media.

PCBs have been linked with effects such as reduced male fertility and long-term behavioural and learning impairment- they are classified as probably carcinogenic to humans. Certain PCBs have been assessed as having dioxin-like effects. PCBs are extremely persistent in the environment and possess the ability to accumulate in the food chain. These compounds are highly insoluble in water but accumulate in body fat. Present human exposure is probably dominated by the accumulation through the food chain of the PCBs present in environmental reservoirs such as soils and sediments as a result of previous releases to the environment.

PCBs have not been manufactured and used in the UK for many years, but old PCB-containing equipment still exist. It is estimated that 81% of primary PCB emissions to the atmosphere are associated with such appliances. These emissions primarily arise from in-service appliances; however emissions during disposal are also considered to be significant. Large quantities of PCBs are thought to have been disposed of to landfill in the past, mainly in the form of electrical components or fragmentiser residues, but now such equipment containing PCBs are disposed of by chemical incineration. This process ensures significant reduction in the amount of PCBs being released into the environment. PCBs are also emitted from the soil having previously been deposited there from the air.

PCB speciation has been incorporated into the emission estimates since the 1998 inventory. A summary of the total PCB emission estimates for 1990 to 2000 is given below in Table 6.7 (detailed emission estimates and TEQs are give in Appendix 8, see http://www.naei.org.uk/).

Table 6.7 - Summary of PCB Emissions in the UK (kg)

	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2000%
BY UN/ECE CATEGORY
Comb. in Energy Prod.
Public Power	91	90	84	72	60	57	52	51	50	44	49	3%
Other Comb. & Trans.	4	1	4	4	4	4	3	4	4	4	4	0%
Comb. in Comm/Inst/Res
Residential Plant	23	25	22	24	20	15	15	16	16	16	10	1%
Comm/Pub/Agri Comb.	2	2	2	2	2	1	1	1	1	1	1	0%
Combustion in Industry
Iron & Steel Comb.	38	37	37	36	37	37	38	39	39	40	36	2%
Other Ind. Comb.	6231	5727	5223	4718	4215	3710	3205	2701	2196	1692	1187	70%
Production Processes
Iron & Steel	491	419	438	458	428	394	373	387	400	243	249	15%
Processes in Industry	1	1	1	1	1	0	0	0	0	0	0	0%
Waste
Landfill	1	1	1	1	1	1	1	1	1	0	0	0%
Waste Incineration	159	159	158	158	155	154	153	149	149	149	149	9%
Other Waste Treat. & Disp.	80	81	78	81	73	64	55	46	38	29	20	1%
Agriculture	1	1	1	0	0	0	0	0	0	0	0	0%
TOTAL	7123	6544	6048	5554	4993	4439	3898	3395	2894	2217	1706	100%

Figure 6.6 UK Emissions of PCBs (kg)

Sales of PCBs in the UK were stopped in 1986, though it is thought that they are still manufactured in some countries. The total PCB emission in 1990 was dominated by leaks from capacitors (87% of total emission), and this is the case for 2000 (70% contribution). However, not all electrical equipment containing PCBs is readily identifiable. Emissions from electrical equipment will probably continue, and will only start to fall significantly as the relevant electrical equipment is either destroyed or reaches the end of its working life.

In 1997 an Action Plan was published by DETR (now Defra) which laid out the commitments made by the UK at the Third International North Sea Conference at the Hague in 1991 in accordance with the requirements of Directive 96/59/EC. Regulations now require all PCB holders in the UK to report their stocks to the relevant regulatory bodies. These stocks (except for certain exemptions) were destroyed before the end of December 2000.

PCBs can be formed in trace amounts from chlorinated precursors in thermal processes such as scrap metal recycling. As a result, there are significant emissions from the iron and steel industrial sector, as with PCDD/Fs.

PCBs occur in sewage sludge due to their persistent nature, and may occur in significant quantities. Not all the PCBs spread on land will volatilise but the potential for emissions to air is greater than that of landfill. The emission estimate comprises only 1% of the total and is highly uncertain. Emissions arise from waste incineration and refuse derived fuel production result from the PCB content of the waste.

Pesticide Emissions

Although there is little available information to enable accurate estimates of pesticide emissions to air, the emission estimates presented here follow from significant improvements to the earlier emission estimates first made in 1996.

Despite these improvements, the confidence in the accuracy of these estimates is low. Relevant data is currently scarce with the majority of emission factors coming from the USA or Europe. The emission factors used here have been derived for a particular method of pesticide application (during specific atmospheric conditions), which may not be representative of the situation in the UK. Until further data becomes available it is difficult to reduce the uncertainty associated with these estimates. At present no relevant measurement programmes are known of, and therefore the possibility of acquiring additional data is considered to be poor.

Pesticide emissions to the air occur predominately through three pathways: during manufacture, during application and volatilisation after application. Tables 6.8, 6.9 and 6.10 show the estimated emissions of lindane (g-HCH), pentachlorophenol (PCP) and hexachlorobenzene (HCB) respectively.

Lindane (g HCH)

Acute (short-term) effects caused by the inhalation of lindane consist of irritation of the nose and throat, as well as effects on the blood. Chronic (long-term) effects through inhalation have been associated with effects on the liver, blood, immune and cardiovascular systems.

Lindane is applied as an insecticide and fungicide in agriculture and is used for wood preservation and in domestic and veterinary formulations. Until 1990 lindane was also used as a remedial wood treatment i.e. in a curative role rather than a preservative/preventative. However, data on quantities used for a remedial wood treatment prior to 1990 are not available.

HCH exists in several isomers, however as a result of regulation in the UK, g-HCH accounts for more than 99% of the total HCH use. Consequently only the g isomer has been considered in any detail here. The emission estimates presented in Table 6.8a were made assuming that emissions arise from: the application of g-HCH, treated wood and agricultural and domestic use. g-HCH emissions are dominated by emissions from treated wood and wood preserving sources, contributing 68% and 11% to the 2000 total emission respectively. Emissions from wood preserving are expected to fall.

Emissions from agricultural activities are also significant, accounting for around 21% of total 2000 g-HCH emissions. These emissions are based on statistics giving the use of pesticides containing lindane, obtained from the Pesticide Usage Survey Group (MAFF, 1991a,b,c; 1992a,b,c,d) The emission factors used are taken from van der Most et al (1989).

Emissions of g-HCH arising from domestic applications are thought to be comparatively small. However, usage statistics are scarce and were only available for 1988 ( DOE, 1989). Emission factors are taken from van der Most et al (1989).

Table 6.8a - Summary of g-HCH Emissions in the UK (tonnes).

	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2000%
BY UN/ECE CATEGORY
Solvent Use
Treated Wood	57	51	46	41	37	33	30	27	24	22	22	68%
Wood Preserving	36	28	21	17	13	10	8	6	5	5	4	11%
Agriculture
Domestic Pesticide Use	1	1	1	1	1	1	1	1	1	1	1	2%
Agriculture Pesticide	6	6	6	6	6	6	6	6	6	6	6	19%
TOTAL	99	85	74	65	57	50	45	40	36	33	32	100%

Figure 6.7 UK Emissions of g-HCH (tonnes)

For completeness, the total emissions of HCH are also included here (see Table 6.8b below), although the differences are obscured due to rounding. These total HCH emissions estimates assume the worst case scenario of 1% contribution from non g isomers to the HCH total.

Table 6.8b - Summary of Total HCH Emissions in the UK (tonnes)

	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2000%
BY UN/ECE CATEGORY
Solvent Use
Treated Wood	57	52	46	42	38	34	30	27	25	22	22	68%
Wood Preserving	36	28	22	17	13	10	8	6	5	5	4	11%
Agriculture
Domestic Pesticide Use	1	1	1	1	1	1	1	1	1	1	1	2%
Agriculture Pesticide	6	6	6	6	6	6	6	6	6	6	6	19%
TOTAL	100	86	75	65	57	51	45	40	36	34	33	100%

Pentachlorophenol (PCP)

Pentachlorophenol is associated with both acute and chronic effects on humans through inhalation. Acute effects can lead to eye irritation as well as having liver, blood and neurological effects. Long-term (chronic) exposure can result in effects on the respiratory tract, immune system, liver, kidneys, blood as well as the eyes and nose.

Pentachlorophenol is used as a biocide, and is effective in destroying insect eggs. It is used in the timber and textile industries. The emission estimates given here also include emissions of sodium pentachlorophenoxide (NaPCP) and pentachlorophenyl laureate (PCPL) as well as PCP since these are also included in the proprietary formulations.

The estimated PCP emissions for 1990 to 2000 are given in Table 6.9. The largest percentage contribution to the total PCP emission arises from wood that has been treated within the last 15 years. This accounts for some 89% of the 2000 total PCP emission.

Once again it is very difficult to be certain of these estimates due to the lack of research into emission rates and limited knowledge of quantities used both in the year of the estimate and in previous years. An emission factor of 3% of the wood content per year was used- the same method used for lindane.

PCP emissions from the textile industry primarily arise from volatilisation during application as a cotton preservative. Emission factors used were based on a study of PCP emissions in the UK (Wild, 1992) who report that approximately 30% of the applied PCP is lost through volatilisation. Emissions from this sector are comparatively small.

PCP is used in the agricultural sector as the active ingredient in disinfecting wooden trays used in mushroom farming (classified as solvent use). Usage statistics are reliable coming from the Pesticide Usage Survey Group (MAFF, 1991a,b,c; 1992a,b,c,d). The emission factor assumes 30% loss due to volatilisation (Wild, 1992). Emissions from this sector are comparatively small.

Table 6.9 - Summary of PCP Emissions in the UK (tonnes)

	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2000%
BY UN/ECE CATEGORY
Comb. in Energy Prod.	0.1	0.1	0.1	0.1	0.2	0.2	0.1	0.1	0.1	0.1	0.1	0%
Comb. in Comm/Inst/Res	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Combustion in Industry	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Production Processes	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Solvent Use
Textile Coating	3.0	3.0	3.0	3.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
NaPCP Treated Wood	3.6	3.6	3.6	1.8	1.8	1.8	1.8	1.8	1.8	1.8	1.8	0%
PCP Treated Wood in Use	474.5	474.5	474.5	474.5	466.6	458.9	451.5	444.3	437.3	430.6	424.1	89%
PCP Treated Wood	6.2	6.2	6.2	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
PCP in Imported Wood	50.0	50.0	50.0	50.0	50.0	50.0	50.0	50.0	50.0	50.0	50.0	11%
Road Transport	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Other Trans/Mach	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Waste	0.3	0.3	0.3	0.3	0.2	0.1	0.1	0.0	0.0	0.0	0.0	0%
Agriculture	0.2	0.2	0.2	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
TOTAL	538	538	538	530	519	511	503	496	489	483	476	100%

Figure 6.8 UK Emissions of PCP (tonnes)

The emission inventory for PCP is very uncertain as only limited emission factors are available on the release of PCP during agricultural activities and statistics are not actively collected on the extent of its usage. There is some data on release of PCP from combustion processes, but the available studies are not consistent with each other suggesting that the uncertainty may be considerable. Without new data becoming available, significant improvements are not expected in the near future.

Hexachlorobenzene (HCB)

Very little information is available on the health effects of HCB via inhalation. However, the lungs may be affected by repeated or prolonged exposure. It is also considered to be a possible carcinogen if long term exposure occurs.

Studies in the USA have identified two main industrial sources of HCB (Mumma et al, 1975) (Jacoff et al, 1986). These are the manufacture of chlorinated solvents (e.g. trichloroethylene, tetrachloroethylene and carbon tetrachloride) and the manufacture of specific pesticides where HCB remains as an impurity. HCB emissions may also arise from combustion sources, but other than waste incineration these could not be estimated though they are believed to be small.

Statistics for chlorinated solvent production in the UK are commercially confidential, hence estimates were made based on UK solvent usage data from the Solvent Industries Association and import and export statistics.

Although there is no UK manufacture of pesticides that results in the production of HCB, pesticides with HCB as an impurity are still imported and used in the UK for agricultural pest control. Statistics for the use of these pesticides is provided by the Pesticide Usage Survey Group (MAFF, 1991a,b,c; 1992a,b,c,d).

HCB emissions in secondary aluminium smelting result from the use of hexachloroethane (HCE) tablets as a degassing agent (van der Most et al, 1992). Regulations now control the use of HCE and so since 1999, very little secondary aluminium is now melted using HCE. Data on the quantity of degassing agent supplied and the quantity of HCE used per tonne of aluminium melted were obtained from industrial experts and van der Most et al (1989).

Emissions from chlorinated solvent production and pesticide application now account for virtually all of the UK HCB emissions (Table 6.10). For 2000, these two sources are estimated to account for 30% and 70%, respectively, of the total HCB emissions. This represents a change in the relative contributions to the total for 1990 where the same sectors contributed 48% and 43% respectively. This change is a direct result of the reduced emissions from the production of chlorinated solvents, but only very small changes are noted between more recent years.

Table 6.10 - Summary of HCB Emissions in the UK (tonnes)

	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2000%
BY UN/ECE CATEGORY
Comm., Public & Agri. Com	0	0	0	0	0	0	0	0	0	0	0	0%
Secondary aluminium prod	104	96	92	105	94	92	98	88	99	0	0	0%
Production Processes
Pentachlorophenol Production	31	31	31	6	6	6	6	6	6	6	6	1%
Picloram Production	0	0	0	0	0	0	0	0	0	0	0	0%
Carbon Tetrachloride Producn.	360	360	360	360	360	360	360	144	144	144	144	18%
Tetrachloroethylene Producn.	81	81	81	81	81	81	81	33	33	33	33	4%
Trichloroethylene Production	135	135	135	135	135	135	135	54	54	54	54	7%
Waste	6	6	5	5	4	3	2	1	1	1	1	0%
Agriculture
Pesticides (Chlorothalonil)	470	470	470	470	470	470	470	470	470	470	470	60%
Pesticides (Chlorthal-dimethyl)	77	77	77	77	77	77	77	77	77	77	77	10%
Pesticides (Quintozine)	2	2	2	2	2	2	2	2	2	2	2	0%
TOTAL	1267	1259	1255	1242	1230	1227	1232	874	885	786	786	100%

Figure 6.9 UK Emissions of HCB (tonnes)

Short Chained Chlorinated Paraffins (SCCP)

Introduction

Short chain chlorinated paraffins (SCCPs) are a range of commercially available chlorinated paraffins with 10-13 carbon atoms. The commercial products are usually mixtures of different carbon chain paraffins with a range of different degrees of chlorination. SCCPs are considered persistent organic pollutants- they do not occur naturally and due to their bioaccumulative and toxicological properties they are of concern to the environment.

Production and Emissions to Air

SCCPs are currently manufactured in the EU and are marketed under a variety of trade names with an average chlorine content of 40-74%. Current consumption in the UK is estimated to be approximately 1000 tonnes per year.

The main uses of SCCPs are in metal working fluids. It has been reported that there are negligible emissions to air of SCCP from production sources, and releases from the majority of industrial consumption results in emissions primarily to water (with very low emissions to air). Emissions from waste water to the atmosphere are unlikely to be large due to the physical properties of SCCPs.

Emission Estimates

Emission estimates have been revised since last years NAEI Report (Goodwin et al., 2001). The new estimates are based on information provided in the European Union Risk Assessment Report (1999) and other data. Emissions of SCCPs have declined considerably since 1990 due to the decrease in consumption generally and the switching to alternatives.

Table 6.11 SCCP emissions in the UK (tonnes)

	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000
TOTAL	48	45	43	41	30	24	18	13	8	6	3

Polychlorinated Napthalenes (PCN)

Introduction

Polychlorinated Napthalenes (PCNs) are a group of 75 theoretically possible chlorinated naphthalenes containing between one and eight chlorine atoms. Their chemical structure is similar to that of PCBs. PCNs are widely considered be associated with cancer and chronic liver disease.

PCNs have been used in a variety of industries. The most important uses are cable insulation, wood preservation, engine oil additives, electroplating masking compounds, feedstock for dye production, dye carriers, capacitors and refractive testing oils.

PCNs have been produced in a number of countries including the UK, USA and France, their synonyms and trade names include Halowax, Nibren waxes, Seekay Waxes, Cerifal Materials and N-Oil. The majority of production generates a standard mixture of the different PCN congeners.

Production and Consumption

A number of assumptions give an estimate of the world-wide PCN production as 150,000 tonnes. Similar assumptions can be made to estimate the UK production as 6,650 tonnes.

Emission Estimates

There is very little information concerning the production of PCNs for commercial purposes.

Commercially produced PCNs are thought to be the most important source of PCNs in the atmosphere with the other source sectors being thermal sources, other industrial processes and contamination in PCB industrially produced mixtures.

PCNs have not been produced in the UK for over 30 years and therefore the major releases that were present during their extensive use have decreased. The potential sources at present are expected to be dominated by the disposal routes of capacitors and engine oil in the past (this is where the majority of the PCNs produced are thought to have been used). Another potential source of PCNs may be the incineration industry, PCNs have been found in fly ash and flue gas in waste incinerators. Similarly landfill is expected to be a source of PCN emissions.

PCNs have been found in emissions from incinerators and are thought to be produced from the combustion of PAHs. Therefore PCNs could in theory be produced from other high temperature combustion processes. A full review of emission measurements from such processes would be required prior to ascertaining the scale of the emissions of PCNs from such a potentially large array of sources.

As the information regarding the emission of PCNs in the UK is relatively sparse, it is not currently realistic to quote an emission estimate for PCNs. It is hoped that data will become available to resolve this in the future. However, at this time, no programmes are known of which would provide the data required to help with the generation of PCN emissions.

Polybrominated Diphenyl Ethers (PBDEs)

Introduction

There are 209 possible congeners of polybrominated diphenyl ethers (PBDEs). Concern about potential risks to human health and the environment has centred on the potential toxicity, persistence and the tendency for bioaccumulation of some brominated diphenyls.

Since the 1960s, PBDEs have been added as flame-retardants. They are used in a variety of materials (Strandman et al. 2000), including thermoplastics (e.g. high-impact polystyrene) that are used in electrical equipment, computer circuit boards, casings, upholstery, furnishings; interiors in cars, buses, trucks and aeroplanes, rugs, drapery and building materials.

Production and Releases to Air

The annual EU production of polybrominated diphenyl ethers has been estimated to be 11,000 tonnes per year. It has been reported (EU 2000) that the UK used up to 2,000 tonnes of polybrominated biphenyl in 1994. Production of the three commercial mixtures (penta-, octa- and deca-dibrominated diphenyl) has virtually ceased in the EU.

The possible routes of release of PBDEs vary from production to the disposal of the materials for which they are used. There is limited information concerning the releases and it is difficult to attempt to estimate an emission inventory without any measurements of releases from sources or potential sources. Attempts have been made to gather UK usage information. However, information is not easily accessible, particularly as PBDEs are a material used in such a wide variety of industries.

Emission Estimate

It has not been possible to obtain UK specific emission data for PBDEs, but an estimate of the UK emission of PBDEs has been made using the total EU estimate. This is done by scaling with population. Without further assessment of the potential emissions from materials such as plastic and upholstery during production use and disposal it is not possible to make a more accurate estimate. The resulting unspeciated UK emission estimate for PBDE’s is 13.8 tonnes per year.

There are a number of improvements that can be made to the UK emission estimate. Resources will be focussed on the following aspects of production and use of secondary products that contain PBDEs.

· Emission from manufacturing sites

· Releases from materials during use

· Release from materials during and following disposal

Improvements arising from this work will be incorporated in the next annual dataset.

Accuracy of Emission Estimates of POPs

Quantitative estimates of the uncertainties in emission inventories have been based on calculations made using a direct simulation technique, which corresponds to the IPCC Tier 2 approach recommended for greenhouse gases and also the methodology proposed in draft guidance produced by the UN ECE Taskforce on Emission Inventories. This work is described in detail by Passant (2002b). The uncertainty estimates are shown below in Table 6.12.

Table 6.12 Uncertainty of the Emission Inventories for persistent organic pollutants

Pollutant	Estimated Uncertainty %
Benzo[a]pyrene	-60% to +200%
Dioxins	-40% to +90%
Polychlorinated biphenyls	+/- 40%
Pentachlorophenol	-70% to +200%
Hexachlorohexane	-80% to +300%
Hexachlorobenzene	-60% to +100%
Short-chain chlorinated paraffins	-90% to +1000%
Pentabromodiphenyl ether	-90% to +1000%
Polychlorinated naphthalenes	not estimated

Inventories for persistent organic pollutants are more uncertain than those for gaseous pollutants, PM₁₀, and metals. This is largely due to the paucity of emission factor measurements on which to base emission estimates, coupled with a lack of good activity data for some important sources. The inventories for polychlorinated biphenyls and short chain chlorinated paraffins are less uncertain than those for other persistent organic pollutants due to the fact that these pollutants are released to air during their use as products and that reasonably robust data are available on the levels of usage. The uncertainty in emission estimates for polychlorinated naphthalenes has not been estimated since no emission estimates are made.

Heavy metal emission estimates

Introduction

The NAEI currently reports emissions of thirteen metals. These are:

· Arsenic · Mercury

· Beryllium · Nickel

· Cadmium · Selenium

· Chromium · Tin

· Copper · Vanadium

· Lead · Zinc

· Manganese

Emissions inventories for all those except beryllium, manganese, selenium, tin, and vanadium were reported by Leech (1993), Gillham et al (1994) and Couling et al (1994). Emissions of all metals except beryllium, manganese and tin were reported by Salway et al (1996, 1996a, 1997, 1999) and Goodwin et al (1999, 2000). Emission estimates for beryllium, manganese, and tin are reported here for the first time.

Heavy metal emissions arise from a number of different sources, but in general fuel combustion and certain industrial processes which produce dust are the main contributors. Metal emissions arise from the trace concentrations in the fuels or in the case of industrial processes, the raw materials. In the case of combustion, metals are emitted either as vapour or particulate matter or both. Volatile metals such as mercury and selenium are mostly emitted as vapour. Metals such as cadmium and lead are emitted as both with some of the vapour condensing onto the ash particles. Other metals such as chromium do not vaporise and may be emitted in the ash particles.

Emission estimates for combustion sources are generally based on emission factors developed from fuel composition data, applied to fuel consumption statistics (DTI, 2000). Emission estimates for industrial processes are generally based on data taken from the Pollution Inventory or based on the use of emission factors and activity data taken from the literature. The methodology for industrial process emissions has recently been reviewed (Passant et al, 2002) and numerous changes have been made. A similar review of the methodology for combustion related sources is currently being undertaken and may lead to revisions to the 2001 version of the NAEI.

UK data is used for the metal contents of coal and fuel oils where available. Emissions from the combustion of liquid fuels are based on data reported by Wood (1996) and other sources in the literature (Sullivan, 1992; Lloyds 1995). Lead emissions from petrol combustion are based on detailed data on the lead content of petrol published by the Institute of Petroleum (1999). The emissions from coal and oil fired power stations are based on estimates reported in the Pollution Inventory (Environment Agency, 2001) or the operators’ annual reports. Emissions from other coal combustion sources follow the PARCOM methodology (van der Most, 1992) but use data based on UK coal (Smith, 1987). Many of the emission factors for industrial processes such as iron & steel, primary lead/zinc manufacture, secondary copper and cement manufacture are based on data given in the Pollution Inventory, although literature-based emission factors are also used (sources include Clayton et al, 1991, EMEP/CORINAIR(1996), van der Most (1992), Jockel and Hartje (1991), and Smyllie, 1996). Details of the methodology are given in Passant et al, 2002. Emissions from the chloralkali industry are based on manufacturers estimates (Ratcliffe, 1999).

Heavy metal emissions can be reduced using gas cleaning equipment which removes particulates from waste gases. This abatement equipment can be fitted to large coal-fired industrial boilers and power station boilers and also industrial processes which produce large amounts of dust. Hence, when estimating emission factors it is often necessary to assume some efficiency of abatement.

The majority of the emission factors used in generating emission estimates are based on the mass of metal emitted per unit mass of fuel burnt, or mass of metal emitted per unit mass of product for processes. These emission factors are assumed not to vary with time for many of the sources considered. This is assumed as there is usually insufficient information to estimate any temporal variation of the emission factor. However, for sources such as road transport, chlorine production, waste incineration and public power generation, there is sufficient information to allow time dependent emission factors to be estimated.

At the end of 1996 all municipal solid waste and clinical incinerators had to comply with new emission standards (see also Section 6.2.2). As a result, a number of old incinerators have closed, whilst some have been renovated and some new ones opened. Hence there have been significant reductions in emissions from waste incineration. Data is available for most metals for the new plant (Environment Agency, 2001).

Emissions of Arsenic

Acute exposure to high levels of arsenic via the inhalation of dust or fumes has led to gastrointestinal effects such as nausea, diarrhea and abdominal pain. Chronic inhalation exposure to inorganic arsenic is associated with irritation of the mucous membranes as well as being strongly associated with lung cancer.

Table 6.13 and Figure 6.10 summarise the UK emissions of arsenic. Emissions have declined by 82% since 1970. The largest source of emission arises from coal combustion with other sources being very small by comparison. Coal use has declined over the period considered, in favour of natural gas use. The emissions from the industrial sector are large compared with the emissions from public power generation; this is due to the different levels of abatement efficiency that are assumed.

Table 6.13 UK Emissions of Arsenic by UN/ECE Category (tonnes)

	1970	1980	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2000%
BY UN/ECE CATEGORY^1
Comb. in Energy Prod.
Public Power	18.1	19.1	18.0	17.7	16.4	13.8	12.4	9.5	8.9	6.1	6.6	5.7	4.3	12%
Petroleum Refining Plants	0.7	0.7	0.5	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.5	0.4	1%
Other Comb. & Trans.	8.9	3.1	0.5	0.5	0.4	0.2	0.1	0.0	0.0	0.0	0.0	0.0	0.1	0%
Comb. in Comm./Inst/Res
Residential Plant	41.6	22.7	13.3	15.1	12.9	15.6	14.4	10.8	11.0	9.1	8.0	7.7	7.3	21%
Comm/Pub/Agri Comb.	21.3	6.1	4.4	4.0	2.6	2.4	1.8	1.4	1.5	1.5	0.9	0.7	0.5	1%
Combustion in Industry
Iron & Steel Comb.	4.1	1.0	0.3	0.3	0.3	0.3	0.3	0.2	0.2	0.1	0.2	0.2	0.1	0%
Non-Ferrous Metals	2.2	1.6	1.5	1.2	1.1	1.2	1.2	1.2	1.2	1.1	1.0	0.9	0.4	1%
Other Ind. Comb.	97.0	41.9	40.4	41.9	47.1	43.8	41.8	39.3	35.0	32.3	27.9	25.4	20.0	58%
Production Processes
Iron & Steel	2.0	0.9	1.5	1.4	1.4	1.4	1.5	1.5	1.5	1.6	1.5	1.4	1.2	3%
Non-Ferrous Metals	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Processes in Industry	0.3	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.1	0.1	0.1	0.1	0.2	1%
Other Trans/Mach	0.0	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0%
Waste	1.1	1.1	0.9	0.8	0.8	0.7	0.5	0.5	0.5	0.0	0.0	0.0	0.0	0%
By FUEL TYPE
Solid	174.4	79.3	62.2	65.4	65.8	62.4	56.7	47.7	43.2	36.6	30.9	28.4	22.5	65%
Petroleum	4.2	2.5	2.1	2.0	1.7	1.5	1.3	1.1	1.1	0.7	0.7	0.6	0.4	1%
Gas	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Non-Fuel	18.6	16.5	17.2	16.4	16.2	16.4	16.6	16.5	16.2	15.3	15.3	13.5	11.6	34%
TOTAL	197.1	98.4	81.6	83.8	83.7	80.3	74.6	65.3	60.5	52.6	46.9	42.6	34.6	100%

1 See Annex 1 for definition of UN/ECE Categories

Figure 6.10 UK Emissions of Arsenic

Emissions of Cadmium

Effects of acute inhalation exposure to cadmium consist mainly of effects on the lung, such as pulmonary irritation. Chronic effects via inhalation can cause a build-up of cadmium in the kidneys that can lead to kidney disease.

Table 6.14 and Figure 6.11 summarise the UK emissions of cadmium. Emissions have declined by 80% since 1970. The main sources are non-ferrous metal production and iron and steel manufacture. The former includes a lead-zinc smelting plant and a number of lead battery recycling plants. The estimate for energy production includes a significant proportion from waste combustion and fuel oil combustion for electricity generation. The decline in emissions is a result of the general fall in coal combustion and the decline in fuel oil combustion in power generation. The large reduction in waste emissions is due to improved controls on MSW incinerators from 1997 onwards and their conversion to power generating plant.

Table 6.14 UK Emissions of Cadmium by UN/ECE Category (tonnes)

	1970	1980	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2000%
BY UN/ECE CATEGORY^1
Comb. in Energy Prod.
Public Power	4.0	3.1	4.2	4.0	3.9	2.4	2.5	1.7	1.4	0.8	0.7	0.5	0.4	8%
Petroleum Refining Plants	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.1	2%
Other Comb. & Trans.	0.2	0.1	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Comb. in Comm/Inst/Res
Residential Plant	1.4	0.7	0.4	0.5	0.4	0.5	0.5	0.4	0.4	0.3	0.3	0.3	0.3	5%
Comm/Pub/Agri Comb.	0.6	0.2	0.7	0.7	0.6	0.2	0.2	0.1	0.1	0.1	0.0	0.0	0.0	1%
Combustion in Industry
Iron & Steel Comb.	2.0	0.9	1.0	0.9	0.9	0.9	0.8	0.7	0.7	0.6	0.6	0.5	0.5	9%
Non-Ferrous Metals	3.9	2.5	2.8	2.9	2.8	3.0	2.8	2.8	2.1	2.6	1.4	1.6	1.3	25%
Other Ind. Comb.	2.9	1.6	1.6	1.5	1.7	1.6	1.6	1.5	1.3	1.2	1.0	0.8	0.6	12%
Production Processes
Iron & Steel	1.1	0.7	1.0	0.9	0.9	0.9	1.0	1.0	1.0	1.0	0.9	0.8	0.7	13%
Non-Ferrous Metals	0.0	0.1	0.1	0.1	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	1%
Processes in Industry	0.7	0.6	0.3	0.3	0.2	0.2	0.2	0.1	0.1	0.1	0.1	0.1	0.1	3%
Road Transport
Combustion	0.2	0.2	0.3	0.3	0.3	0.4	0.4	0.4	0.4	0.4	0.4	0.4	0.4	7%
Brake & Tyre Wear	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Other Trans/Mach	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	1%
Waste	9.4	9.4	7.7	7.7	7.5	3.4	3.2	2.8	1.6	0.5	0.6	0.6	0.6	12%
By FUEL TYPE
Solid	5.7	3.5	2.9	3.0	2.9	2.6	2.4	2.0	1.8	1.5	1.4	1.1	1.0	18%
Petroleum	3.1	2.0	1.9	1.8	1.5	1.3	1.1	1.0	1.1	0.7	0.7	0.7	0.6	12%
Gas	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Non-Fuel	17.8	15.0	15.5	15.2	15.2	9.8	9.8	8.8	6.4	5.6	4.3	4.1	3.6	70%
TOTAL	26.6	20.4	20.3	19.9	19.6	13.8	13.3	11.8	9.4	7.8	6.3	5.9	5.2	100%

1 See Annex 1 for definition of UN/ECE Categories

Figure 6.11 UK Emissions of Cadmium

Emissions of Chromium

Inhaled chromium is a carcinogen, leading to an increased risk of lung cancer. Acute exposure effects can result in shortness of breath, coughing and wheezing, whilst chronic exposure effects lead to perforation and ulceration of the septum, bronchitis, pneumonia, and decreased pulmonary function.

Table 6.15a and Figure 6.12 summarise the UK emissions of chromium. Emissions have fallen by 71% since 1970. The largest sources are various forms of coal combustion, iron and steel production in integrated works and in electric arc furnaces and the production of chromium-based chemicals.

Table 6.15a UK Emissions of Chromium by UN/ECE Category (tonnes)

	1970	1980	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2000%
BY UN/ECE CATEGORY^1
Comb. in Energy Prod.
Public Power	50.6	57.5	55.2	54.8	52.0	44.8	42.5	31.9	27.8	17.3	17.1	17.4	14.5	23%
Petroleum Refining Plants	0.5	0.5	0.3	0.4	0.4	0.4	0.4	0.4	0.4	0.4	0.4	0.4	0.3	0%
Other Comb. & Trans.	3.1	1.1	0.2	0.2	0.1	0.1	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Comb. in Comm/Inst/Res
Residential Plant	28.3	13.4	7.0	7.7	6.6	7.5	6.5	4.7	4.8	4.2	3.9	3.9	3.3	5%
Comm/Pub/Agri Comb.	8.3	2.5	2.6	2.6	2.1	2.0	1.8	1.4	1.1	0.7	0.5	0.4	0.2	0%
Combustion in Industry
Iron & Steel Comb.	3.2	1.1	0.7	0.6	0.6	0.7	0.6	0.4	0.3	0.2	0.2	0.2	0.2	0%
Non-Ferrous Metals	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0%
Other Ind. Comb.	45.4	24.7	22.6	22.1	24.7	23.1	22.2	20.2	18.3	16.0	13.5	11.3	9.2	15%
Production Processes
Iron & Steel	22.0	17.5	18.7	15.9	16.6	17.3	17.6	18.2	17.2	18.2	15.8	10.5	7.8	12%
Non-Ferrous Metals	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Processes in Industry	44.4	41.7	35.0	32.1	34.2	35.2	34.2	31.3	25.1	28.4	27.3	22.1	26.8	43%
Road Transport	0.2	0.2	0.3	0.3	0.3	0.4	0.4	0.4	0.4	0.4	0.4	0.4	0.4	1%
Other Trans/Mach	0.2	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0%
Waste	13.1	13.1	9.9	9.8	9.4	8.5	6.2	4.1	2.1	0.0	0.0	0.0	0.0	0%
By FUEL TYPE
Solid	117.4	83.2	68.8	69.6	66.8	57.6	51.3	40.1	36.8	26.7	24.5	24.9	20.0	32%
Petroleum	10.9	6.1	3.4	3.6	3.5	3.5	3.2	2.6	2.5	1.9	1.7	1.4	1.1	2%
Gas	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Non-Fuel	91.2	84.0	80.5	73.6	77.1	79.1	78.0	70.6	58.5	57.6	53.2	40.5	41.8	67%
TOTAL	219.4	173.4	152.8	146.8	147.5	140.2	132.5	113.3	97.7	86.1	79.3	66.7	62.8	100%

1 See Annex 1 for definition of UN/ECE Categories

Figure 6.12 UK Emissions of Chromium

6.1.1.1 Speciation of chromium

Chromium may be emitted to air in two oxidised forms - hexavalent (Cr⁶⁺) and trivalent (Cr³⁺). The proportion of each form emitted by each source has been estimated and the overall split between the two forms is shown in Table 6.15b

Table 6.15b. Speciated Emissions of Chromium (tonnes)

	Cr^6+	Cr^3+	Total (2000)
BY UN/ECE CATEGORY^1
Comb. in Energy Prod.	1.65	13.12	14.77
Comb. in Comm/Inst/Res	0.37	3.14	3.51
Combustion in Industry	0.90	8.54	9.44
Production Processes	4.41	30.21	34.62
Road Transport	0.07	0.29	0.37
Other Trans/Mach	0.01	0.05	0.06
Waste	0.00	0.03	0.04
TOTAL	7.42	55.39	62.81

The profiles used for the speciation are based on the recommendations given in Passant et al, 2002. In general, these profiles are subject to great uncertainty and further measurement data are required, particularly for major sources such as coal combustion, glass production, electric arc furnaces and chemical processes (other than chromium chemicals for which good data are available).

Emissions of Copper

Acute effects of copper fumes can lead to irritation of the eyes, nose and throat, resulting in coughing, wheezing and nosebleeds. It may also cause 'metal fume fever', which is a flu-like illness that has symptoms of a metallic taste, fever, chill, aches and chest tightness. Chronic exposure may lead to decreased fertility in both men and women. Severe irritation and ulcers in the nose may also occur.

Table 6.16 and Figure 6.13 summarise the UK emissions of copper. Emissions have declined by 79% since 1970. The main sources are coal combustion, iron and steel manufacture and non-ferrous metals production. Emissions have declined over the period due to the decline in coal combustion and to a lesser extent the combustion of heavy fuel oil. The large reduction in waste emissions is due to improved controls on MSW waste incinerators from 1997 and their conversion to power generating plant.

Table 6.16 UK Emissions of Copper by UN/ECE Category (tonnes)

	1970	1980	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2000%
BY UN/ECE CATEGORY^1
Comb. in Energy Prod.
Public Power	39.5	44.5	44.1	43.8	41.8	36.9	36.4	27.3	23.1	13.8	16.5	13.0	13.2	29%
Petroleum Refining Plants	1.0	1.0	0.7	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.7	0.5	1%
Other Comb. & Trans.	4.0	1.4	0.2	0.2	0.2	0.1	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Comb. in Comm/Inst/Res
Residential Plant	18.9	10.3	6.1	6.9	5.9	7.2	6.6	5.0	5.1	4.3	3.8	3.6	3.4	8%
Comm/Pub/Agri Comb.	26.9	11.1	8.1	7.9	6.8	5.9	5.2	3.8	3.6	3.3	2.3	2.2	1.7	4%
Combustion in Industry
Iron & Steel Comb.	7.8	2.7	3.4	3.3	3.2	3.2	3.3	3.4	3.5	3.5	3.4	3.3	3.0	7%
Non-Ferrous Metals	32.7	25.6	20.0	13.3	10.1	10.8	11.4	12.2	12.7	13.6	12.1	10.8	4.0	9%
Other Ind. Comb.	49.3	20.9	17.3	18.1	20.6	19.1	17.9	16.0	13.7	12.2	9.8	9.7	6.9	15%
Production Processes
Iron & Steel	10.7	5.5	8.2	7.6	7.5	7.6	7.8	8.0	8.1	8.4	7.8	7.0	6.4	14%
Non-Ferrous Metals	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Processes in Industry	1.8	1.3	1.5	1.5	1.5	1.5	1.5	1.6	12.8	5.2	5.2	5.1	5.3	12%
Road Transport	0.3	0.4	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.6	1%
Other Trans/Mach	0.3	0.1	0.1	0.1	0.1	0.1	0.2	0.2	0.2	0.1	0.1	0.1	0.1	0%
Waste	19.7	19.7	15.4	15.3	14.7	13.4	10.2	7.4	4.0	0.4	0.4	0.4	0.4	1%
By FUEL TYPE
Solid	123.7	78.6	65.2	66.2	64.0	56.6	50.8	40.5	37.3	29.5	28.7	24.7	22.8	50%
Petroleum	16.5	9.3	5.2	5.5	5.4	5.3	4.9	4.1	3.8	3.1	2.8	2.3	1.8	4%
Gas	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Non-Fuel	72.8	56.7	55.5	47.6	44.5	45.3	46.4	41.6	47.0	33.6	31.4	29.6	21.1	46%
TOTAL	213.0	144.6	125.9	119.3	113.9	107.3	102.0	86.2	88.1	66.2	62.9	56.6	45.7	100%

1 See Annex 1 for definition of UN/ECE Categories

Figure 6.13 UK Emissions of Copper

Emissions of Lead

Lead is a very toxic element and can cause a variety of symptoms at low dose levels. Lead dust or fumes can irritate the eyes on contact, as well as causing irritation to the nose and throat on inhalation. Acute exposure can lead to loss of appetite, weight loss, stomach upsets, nausea and muscle cramps. High levels of acute exposure may also cause brain and kidney damage. Chronic exposure can lead to effects on the blood, kidneys, central nervous system and vitamin D metabolism.

Table 6.17 and Figure 6.14 summarise the UK emissions of lead. Emissions have declined by 93% since 1970. The largest source is lead from anti-knock lead additives in petrol. The lead content of leaded petrol was reduced from around 0.34 g/l to 0.143 g/l in 1986 and since 1987 sales of unleaded petrol have increased particularly as a result of the increased use of cars fitted with catalytic converters. Leaded petrol was then phased out from general sale at the end of 1999. Consequently a decline in emissions from the road transport sector is seen.

Other major sources are industrial processes and iron and steel combustion. There has been some reduction in emissions from iron and steel production processes due to improved abatement measures. Emissions have also declined as a result of the decreasing use of coal. The large reduction in waste emissions is due to improved controls on MSW incinerators from 1997 onwards and their conversion to power generating plant.

Table 6.17 UK Emissions of Lead by UN/ECE Category (tonnes)

	1970	1980	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2000%
BY UN/ECE CATEGORY^1
Comb. in Energy Prod.
Public Power	81.4	88.5	103.8	99.4	95.6	85.4	103.3	80.5	60.1	25.6	26.4	17.0	17.5	4%
Petroleum Refining Plants	0.9	0.9	0.6	0.7	0.7	0.7	0.7	0.7	0.7	0.7	0.7	0.6	0.5	0%
Other Comb. & Trans.	12.7	4.4	0.8	0.7	0.5	0.3	0.1	0.1	0.1	0.1	0.0	0.1	0.1	0%
Comb. in Comm/Inst/Res
Residential Plant	100.5	49.3	26.6	29.4	25.7	29.3	25.8	19.2	19.7	16.9	15.6	15.5	13.6	3%
Comm/Pub/Agri Comb.	49.4	18.0	19.8	19.8	16.8	15.3	14.5	10.5	7.6	4.4	3.0	2.6	2.0	0%
Combustion in Industry
Iron & Steel Comb.	78.8	28.4	48.6	46.6	45.5	45.2	45.9	46.2	47.7	47.8	46.7	44.6	40.0	8%
Non-Ferrous Metals	60.7	43.4	43.9	40.2	38.1	40.6	38.6	38.6	33.1	32.6	23.4	21.9	15.9	3%
Other Ind. Comb.	193.3	114.9	119.4	115.9	126.9	123.3	118.4	107.0	93.1	77.3	63.4	53.3	38.1	8%
Production Processes
Iron & Steel	34.8	28.0	30.4	26.0	27.1	28.1	28.7	29.6	28.0	29.7	25.8	22.5	23.7	5%
Non-Ferrous Metals	1.2	0.8	1.0	0.9	0.8	0.8	0.8	0.9	0.9	0.9	0.9	0.6	0.6	0%
Processes in Industry	131.9	126.2	124.0	123.4	123.1	122.9	124.0	110.4	97.2	136.3	91.8	30.5	14.2	3%
Road Transport	6363	7445	2173	1937	1726	1525	1295	1065	909	799	591	331	326	66%
Other Trans/Mach	119.0	91.8	18.6	17.5	15.9	13.9	12.2	10.1	8.6	7.6	5.9	3.5	0.8	0%
Waste	148.9	149.0	117.3	116.3	112.3	102.7	79.3	58.0	30.0	3.4	3.6	3.7	3.7	1%
By FUEL TYPE
Solid	355	196	153	154	148	126	113	98	93	75	67	55	47	10%
Petroleum	6512	7553	2201	1964	1751	1546	1314	1081	923	810	600	338	328	66%
Gas	0	0	0	0	0	0	0	0	0	0	0	0	0	0%
Non-Fuel	511	440	473	456	457	461	460	398	320	297	231	155	120	24%
TOTAL	7377	8189	2828	2574	2355	2133	1888	1577	1335	1182	898	548	496	100%

1 See Annex 1 for definition of UN/ECE Categories

Figure 6.14 UK Emissions of Lead

Emissions of Mercury

Acute exposure to high levels of mercury vapour can lead to irritation of the lungs as well as causing coughing, chest pain and shortness of breath. High levels can also result in central nervous system (CNS) effects such as tremors and mood changes. Chronic exposure also leads to CNS disorders, with effects such as increased excitability, excessive shyness and irritability.

Table 6.18a and Figure 6.15 summarise the UK emissions of mercury. Emissions have declined by 81% since 1970. The main sources are waste incineration, the manufacture of chlorine in mercury cells, non-ferrous metal production and coal combustion. Emissions have declined as a result of improved controls on mercury cells and their replacement by diaphragm or membrane cells and the decline of coal use. The large reduction in waste emissions is due to improved controls on MSW incinerators from 1997 onwards and their conversion to power generating plant. There are only relatively minor changes since the last inventory. There is an increase in cement kiln emissions in ‘industrial combustion’ and a small revision upwards in MSW incineration emissions.

Table 6.18a UK Emissions of Mercury by UN/ECE Category (tonnes)

	1970	1980	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2000%
BY UN/ECE CATEGORY^1
Comb. in Energy Prod.
Public Power	7.5	8.1	8.4	8.3	7.9	5.0	4.8	4.4	2.9	3.0	2.7	1.7	1.4	17%
Petroleum Refining Plants	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.0	1%
Other Comb. & Trans.	0.5	0.2	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Comb. in Comm/Inst/Res
Residential Plant	3.9	1.9	1.0	1.2	1.0	1.2	1.0	0.8	0.8	0.7	0.6	0.6	0.5	6%
Comm/Pub/Agri Comb.	2.3	0.9	1.0	1.0	0.8	0.4	0.4	0.3	0.3	0.3	0.2	0.2	0.1	2%
Combustion in Industry
Iron & Steel Comb.	1.3	0.5	0.6	0.5	0.5	0.5	0.6	0.6	0.6	0.6	0.6	0.6	0.5	6%
Non-Ferrous Metals	4.0	2.5	2.9	3.0	2.9	3.1	2.9	2.9	2.3	1.9	1.4	0.3	0.7	9%
Other Ind. Comb.	5.6	2.4	2.4	2.4	2.6	2.5	2.4	2.3	2.0	1.9	1.7	1.3	1.0	11%
Production Processes
Iron & Steel	0.6	0.3	0.4	0.4	0.4	0.4	0.4	0.4	0.4	0.5	0.4	0.4	0.5	5%
Non-Ferrous Metals	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Processes in Industry	11.3	10.2	8.1	8.9	7.4	3.3	3.6	4.2	2.4	1.1	1.3	1.5	1.4	17%
Road Transport	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Other Trans/Mach	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Waste
Landfill	0.6	0.6	0.6	0.6	0.5	0.5	0.4	0.4	0.4	0.4	0.4	0.4	0.4	5%
Waste Incineration	7.3	7.6	6.4	6.4	6.2	3.1	3.0	2.9	2.4	1.8	1.8	1.8	1.8	21%
By FUEL TYPE
Solid	18.2	12.3	10.4	10.5	10.1	7.9	7.3	6.6	4.8	3.9	4.2	3.3	2.7	32%
Petroleum	1.2	0.7	0.6	0.5	0.4	0.4	0.3	0.3	0.3	0.1	0.1	0.1	0.1	1%
Gas	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Non-Fuel	25.6	22.3	20.9	21.5	20.0	11.8	12.0	12.3	9.4	8.2	6.8	5.5	5.7	67%
TOTAL	45.0	35.3	31.8	32.6	30.5	20.1	19.6	19.2	14.6	12.2	11.1	8.9	8.5	100%

1 See Annex 1 for definition of UN/ECE Categories

Figure 6.15 UK Emissions of Mercury

Speciation of Mercury Emissions

When mercury is emitted to air it occurs in one of several different forms, and the emissions of each of these forms has been estimated individually- the emissions have been “speciated”.

Three species of mercury have been considered

· Hg⁰ unreactive gaseous elemental Hg

· Hg-p mercury attached to particulate material

· RGM reactive gaseous mercury (includes both inorganic and organic forms normally in the Hg²⁺ oxidised form)

The methodology for estimating the emissions of each of these three species is similar to that used for speciating the VOC emissions. Each source of mercury emission is considered individually. A speciation profile identifying the fractional contribution from each species to the mercury emission from that source is then applied. Summing across the individual sources then allows a total for each of the three species to be evaluated.

Table 6.18b Speciated Emissions of Mercury (tonnes)

	Hg(0)	Hg-p	RGM	Total (2000)
BY UN/ECE CATEGORY^1
Comb. in Energy Prod.	0.71	0.14	0.65	1.50
Comb. in Comm/Inst/Res	0.28	0.12	0.28	0.68
Combustion in Industry	1.57	0.15	0.52	2.24
Production Processes	1.38	0.03	0.49	1.90
Road Transport	0.00	0.00	0.00	0.00
Other Trans/Mach	0.00	0.00	0.00	0.00
Waste	0.43	0.06	1.73	2.22
TOTAL	4.37	0.49	3.67	8.54

The profiles used for the speciation are based on the recommendations given in Passant et al, 2002. In general, these profiles are subject to great uncertainty and further measurement data are required, particularly for major sources such as coal combustion, crematoria, clinical waste incinerators, sinter plant, chloralkali processes, and primary lead/zinc production.

Emissions of Nickel

Inhalation of nickel can cause irritation to the nose and sinuses and can also lead to the loss of the sense of smell. Long term exposure may lead to asthma or other respiratory diseases. Cancer of the lungs, nose and sinuses as well as the larynx and stomach has all been attributed to exposure to nickel.

Table 6.19a and Figure 6.16 summarise the UK emissions of nickel. Emissions have declined by 91% since 1970. The main sources of nickel emissions are the combustion of coal and heavy fuel oil. These have declined in use since 1970 in favour of natural gas and are largely responsible for the reduction in total emissions. Since 1989 heavy fuel oil has been replaced by Orimulsion (an emulsion of bitumen in water) in some power stations though this has now been discontinued. The nickel content of Orimulsion was higher than that of heavy fuel oil and resulted in higher emissions in spite of the flue gas cleaning equipment required on these power stations. Emissions from refineries are important because of the large amount of refinery fuel oil and residues burnt.

Table 6.19a UK Emissions of Nickel by UN/ECE Category (tonnes)

	1970	1980	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2000%
BY UN/ECE CATEGORY^1
Comb. in Energy Prod.
Public Power	143.5	95.5	97.0	93.7	94.2	83.7	71.9	60.5	53.9	17.2	15.8	11.3	11.9	10%
Petroleum Refining Plants	47.5	45.8	33.4	37.0	37.8	39.3	38.9	38.5	38.6	37.5	38.6	34.1	26.5	23%
Other Comb. & Trans.	12.1	4.2	0.7	0.7	0.5	0.3	0.1	0.1	0.1	0.1	0.0	0.1	0.1	0%
Comb in Comm/Inst/Res
Residential Plant	159.0	71.4	34.9	37.8	33.1	36.0	30.2	21.9	22.2	19.5	18.5	19.2	15.3	13%
Comm/Pub/Agri Comb.	190.0	78.9	40.3	40.1	41.2	43.1	42.9	36.0	33.2	24.3	19.0	19.8	9.1	8%
Combustion in Industry
Iron & Steel Comb.	42.2	10.4	4.7	4.8	4.7	5.8	5.7	5.5	4.4	4.2	2.7	2.9	2.1	2%
Non-Ferrous Metals	0.3	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.3	0.3	0.7	0.1	0%
Other Ind. Comb.	671.5	362.2	175.5	192.1	198.7	188.3	171.3	130.4	109.9	90.3	70.6	44.8	29.7	26%
Production Processes
Iron & Steel Comb.	17.6	13.2	14.8	12.8	13.2	13.7	14.0	14.4	13.8	14.6	12.8	6.5	6.9	6%
Non-Ferrous Metals	0.6	3.9	3.1	3.1	2.6	2.5	2.4	2.5	2.5	2.6	2.7	2.9	3.2	3%
Processes in Industry	6.2	6.0	7.4	7.7	7.6	7.4	7.8	8.8	8.6	6.8	7.4	7.3	7.2	6%
Road Transport	0.7	0.9	1.2	1.2	1.2	1.3	1.3	1.3	1.3	1.3	1.3	1.3	1.3	1%
Other Trans/Mach	13.2	2.9	2.9	4.2	4.4	5.5	6.7	7.5	6.0	4.6	3.8	2.7	1.6	1%
Waste	7.9	7.9	6.0	5.9	5.7	5.1	3.7	2.5	1.3	0.0	0.0	0.0	0.0	0%
By FUEL TYPE
Solid	341.1	156.8	110.7	115.5	113.9	106.9	94.1	76.7	70.6	59.7	55.6	49.0	40.0	35%
Petroleum	930.5	507.6	269.1	286.4	291.3	284.9	262.1	214.4	190.3	132.5	108.6	82.8	54.3	47%
Gas	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Non-Fuel	40.5	39.0	42.4	39.4	39.8	40.3	40.7	38.9	35.1	30.9	29.3	21.8	20.9	18%
TOTAL	1312.2	703.4	422.2	441.3	445.1	432.1	396.9	330.0	296.0	223.1	193.5	153.6	115.1	100%

1 See Annex 1 for definition of UN/ECE Categories

Figure 6.16 UK Emissions of Nickel

6.1.1.2 Speciation of Nickel Emissions

Nickel is emitted to air in a many different forms, which have been grouped into five 'species' for the NAEI:

· MN metallic nickel

· ON oxidic nickel compounds such as NiO and Ni₂O₃

· SolN soluble nickel salts such as nickel sulphates and nickel chlorides

· NC nickel carbonyl, Ni(CO)₄

· SU sulphidic nickel compounds such as nickel sulphide (NiS) and nickel subsulphide (Ni₃S₂)

The proportion of each form emitted by each source has been estimated and the overall split between the two forms is shown in Table 6.19b

Table 6.19b Speciated Emissions of Nickel (tonnes)

	MN	ON	SolN	NC	SU	Total (2000)
BY UN/ECE CATEGORY^1
Comb. in Energy Prod.	0.0	15.0	22.1	0.2	1.2	38.5
Comb. in Comm/Inst/Res	0.0	9.5	14.1	0.1	0.7	24.5
Combustion in Industry	0.0	12.9	18.0	0.1	0.9	31.9
Production Processes	4.1	12.6	0.5	0.1	0.0	17.3
Road Transport	0.0	0.5	0.8	0.0	0.0	1.3
Other Trans/Mach	0.0	0.7	1.0	0.0	0.1	1.7
Waste	0.0	0.0	0.0	0.0	0.0	0.0
TOTAL	4.1	51.2	56.4	0.6	2.8	115.2

The profiles used for the speciation are based on the recommendations given in Passant et al, 2002. In general, these profiles are subject to great uncertainty and better data are desirable, particularly for major sources such as combustion of coal, fuel oil, anthracite, and petroleum coke, and electric arc furnaces. However current measurement techniques are not able to provide much useful data and so significant improvements are not likely in the short term.

Emissions of Selenium

Acute exposure to selenium by inhalation results in respiratory effects such as irritation to the mucous membranes, severe bronchitis and bronchial pneumonia.

Table 6.20 and Figure 6.17 summarise the UK emissions of selenium. Emissions have declined by 73% since 1970. The main source of selenium emissions is coal combustion in early years. Only trace amounts are emitted by the combustion of petroleum based fuels. Emissions have reduced over time because of the decline in coal use in favour of natural gas combustion. Consequently glass production is now the dominant source. The estimates for the manufacture of the various types of glass products (flat glass, container glass etc.) are uncertain because they are based on very limited data.

Table 6.20 UK Emissions of Selenium by UN/ECE Category (tonnes)

	1970	1980	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2000%
BY UN/ECE CATEGORY
Comb. in Energy Prod.
Public Power	53.4	59.9	55.4	54.8	51.3	42.7	37.8	28.7	26.5	17.6	22.0	11.5	14.1	28%
Petroleum Refining Plants	2.0	1.9	1.1	1.2	1.2	1.3	1.3	1.2	1.2	1.2	1.2	1.0	0.7	1%
Other Comb. & Trans.	2.5	0.9	0.2	0.1	0.1	0.1	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Comb. in Comm/Inst/Res
Residential Plant	32.7	14.8	7.3	7.9	7.0	7.6	6.3	4.5	4.7	4.1	3.9	4.0	3.2	6%
Comm/Pub/Agri Comb.	8.7	2.9	1.8	1.7	1.3	1.3	1.1	0.9	0.9	0.8	0.5	0.5	0.3	1%
Combustion in Industry
Iron & Steel Comb.	4.9	1.6	2.4	2.3	2.2	2.2	2.3	2.4	2.4	2.5	2.4	2.3	2.1	4%
Non-Ferrous Metals	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Other Ind. Comb.	81.2	68.2	76.8	69.5	77.2	78.0	73.6	64.1	58.6	51.6	43.1	35.2	28.8	58%
Production Processes
Iron & Steel Comb.	0.3	0.1	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.3	0.2	0.2	0.2	0%
Non-Ferrous Metals	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Processes in Industry	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.1	0%
Road Transport	0.2	0.2	0.3	0.3	0.3	0.4	0.4	0.4	0.4	0.4	0.4	0.4	0.4	1%
Other Trans/Mach	0.2	0.0	0.0	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.0	0.0	0%
Waste	0.2	0.2	0.1	0.1	0.1	0.1	0.1	0.0	0.0	0.0	0.0	0.0	0.0	0%
By FUEL TYPE
Solid	117.2	84.6	70.8	71.5	68.2	59.4	52.5	41.0	37.7	28.1	30.9	20.0	20.4	41%
Petroleum	15.7	9.2	5.2	5.4	5.1	5.0	4.6	3.8	3.6	2.9	2.6	2.3	1.6	3%
Gas	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0%
Non-Fuel	53.4	57.0	69.7	61.5	67.7	69.5	66.2	57.8	53.8	47.6	40.4	33.1	27.9	56%
TOTAL	186.3	150.8	145.7	138.4	141.1	133.9	123.3	102.6	95.1	78.6	73.9	55.3	49.9	100%

1 See Annex 1 for definition of UN/ECE Categories

Figure 6.17 UK Emissions of Selenium

Emissions of Vanadium

Acute exposure to vanadium by inhalation can cause irritation to the respiratory tract. Chronic exposure may lead to pneumonia.

Table 6.21 and Figure 6.18 summarise the UK emissions of vanadium. Emission data are rather scarce so the estimates are very uncertain. Estimates of emissions have declined by 96% since 1970. The major source of emissions is the combustion of fuel oils with liquid fuels accounting for some 73% of the estimated emission in 2000. The reduction in emissions reflects the decline in the use of fuel oils by the electricity supply industry, industry in general and the domestic sector. Since 1989, heavy fuel oil was partly replaced by Orimulsion (an emulsion of bitumen in water) in some power stations though this has now been discontinued. Emissions from refineries are very important because of the high consumption of refinery fuel oil and residues. The vanadium content of Orimulsion was higher than that of heavy fuel oil and resulted in higher emissions in spite of the flue gas cleaning equipment required on these power stations. Of the other sources, estimates for the iron and steel industry are very uncertain since emissions will depend on the type of steel or alloy produced and its vanadium content. The available emissions data apply only to a generalised steel production process.

Table 6.21 UK Emissions of Vanadium by UN/ECE Category (tonnes)

	1970	1980	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2000%
BY UN/ECE CATEGORY^1
Comb. in Energy Prod.
Public Power	498	285	295	283	292	262	212	186	176	39	19	15	18	0
Petroleum Refining Plants	25	18	16	21	22	25	25	20	24	14	15	13	13	0
Other Comb. & Trans.	12	4	1	1	0	0	0	0	0	0	0	0	0	0
Comb. in Comm/Inst/Res
Residential Plant	68	34	18	20	17	20	20	16	14	12	10	10	9	0
Comm/Pub/Agri Comb.	663	287	140	140	150	158	160	135	124	89	71	75	34	0
Combustion in Industry
Iron & Steel Comb.	148	37	17	18	17	21	21	21	16	16	10	11	8	5%
Other Ind. Comb.	2267	1274	545	606	608	580	523	376	314	249	192	102	63	40%
Production Processes
Iron & Steel Comb.	12	7	9	9	9	9	9	9	9	10	9	6	5	3%
Non-Ferrous Metals	0	0	0	0	0	0	0	0	0	0	0	0	0	0%
Road Transport	0	0	1	1	1	1	1	1	1	1	1	1	1	0%
Other Trans/Mach	51	11	11	16	17	21	26	29	23	17	14	10	6	4%
Waste	3	3	2	2	2	2	1	1	0	0	0	0	0	0%
By FUEL TYPE
Solid	227	112	92	96	96	89	81	68	61	51	45	39	35	22%
Petroleum	3501	1834	948	1007	1026	997	902	711	628	384	284	196	114	73%
Gas	0	0	0	0	0	0	0	0	0	0	0	0	0	0%
Non-Fuel	18	12	15	13	13	13	14	13	13	12	11	7	8	5%
TOTAL	3746	1959	1054	1116	1135	1100	997	792	702	446	340	242	157	100%

1 See Annex 1 for definition of UN/ECE Categories

Figure 6.18 UK Emissions of Vanadium

Emissions of Zinc

Although zinc metal poses no documented health risks, if its physical state is altered during use then health risks can be created. Inhalation of metallic oxide fumes can lead to metal fume fever.

Table 6.22 and Figure 6.19 summarise the UK emissions of zinc. Emissions of zinc have declined by 73% since 1970. The main sources are iron and steel production and combustion in industry. The road transport emission is almost entirely due to tyre wear. This arises from the zinc content of the tyre rubber - around 2% ZnO by weight. The reduction in emissions over the period considered is largely due to the decline in coal combustion and improvements in abatement measures in the iron and steel industry. The large reduction in waste emissions is due to improved controls on MSW incinerators from 1997 onwards and their conversion to power generating plant.

Table 6.22 UK Emissions of Zinc by UN/ECE Category (tonnes)

	1970	1980	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2000%
BY UN/ECE CATEGORY^1
Comb. in Energy Prod.
Public Power	31	32	66	66	71	84	130	96	69	33	33	21	9	3%
Petroleum Refining Plants	16	16	11	12	13	13	13	13	13	13	13	12	9	3%
Other Comb. & Trans.	36	13	2	2	1	1	0	0	0	0	0	0	0	0%
Comb. in Comm/Inst/Res
Residential Plant	56	25	12	13	12	12	10	7	7	7	7	7	6	2%
Comm/Pub/Agri Comb.	91	27	35	34	27	25	23	17	12	7	5	3	2	1%
Combustion in Industry
Iron & Steel Comb.	27	8	6	6	6	6	6	5	5	4	5	4	4	1%
Non-Ferrous Metals	158	110	106	94	87	92	90	95	93	94	77	65	49	15%
Other Ind. Comb.	391	165	163	166	191	179	169	154	134	121	99	88	66	20%
Production Processes
Iron & Steel	396	290	347	304	312	321	329	339	328	345	308	201	161	48%
Non-Ferrous Metals	0	4	3	3	2	2	2	2	2	2	3	3	3	1%
Processes in Industry	40	37	20	17	15	12	13	13	14	13	13	13	11	3%
Road Transport
Combustion	0	1	1	1	1	1	1	1	1	1	1	1	1	0%
Brake & Tyre Wear	4	6	9	9	9	9	9	10	10	10	10	10	11	3%
Other Trans/Mach	0	0	0	0	0	0	0	0	0	0	0	0	0	0%
Waste	230	231	178	177	170	154	116	82	43	3	4	5	5	1%
By FUEL TYPE
Solid	564	215	175	181	194	175	159	141	124	110	94	84	62	18%
Petroleum	39	28	19	20	19	19	18	17	17	16	16	14	10	3%
Gas	0	0	0	0	0	0	0	0	0	0	0	0	0	0%
Non-Fuel	875	721	768	704	706	719	734	676	593	529	468	337	264	78%
TOTAL	1477	964	961	905	919	913	912	835	734	655	578	434	336	100%

1 See Annex 1 for definition of UN/ECE Categories

Figure 6.19 UK Emissions of Zinc

Emissions of Beryllium

Acute inhalation exposure to high levels of beryllium can lead to inflammation of the lungs. Long term exposure can cause chronic beryllium disease where non-cancerous lesions form in the lungs. Studies also suggest that inhalation can lead to an increased risk of lung cancer.

Emissions estimates of Beryllium appear here for the first time.

Table 6.23 summarises the UK emissions of beryllium. Estimates have been included in the NAEI for the first time and the figures are very uncertain. Emission factors have been calculated for the combustion of coal and heavy liquid fuels, but emission factors are not available for industrial processes, with the exception of iron & steel manufacture and a few other processes, where emission estimates have been based on data given in the Pollution Inventory. Further development of the beryllium inventory will occur in future versions of the NAEI.

Table 6.23 UK Emissions of Beryllium by UN/ECE Category (Ktonnes)

	2000	2000%
BY UN/ECE CATEGORY^1
Comb. in Energy Prod.
Public Power	1	4%
Petroleum Refining Plants	1	5%
Other Comb. & Trans.	2	16%
Comb. in Comm/Inst/Res
Residential Plant	4	23%
Comm/Pub/Agri Comb.	1	7%
Combustion in Industry	1	8%
Production Processes	1	4%
Road Transport	5	29%
Other Trans/Mach	0	3%
Waste	0	0%
By FUEL TYPE
Solid	7	48%
Petroleum	8	49%
Gas	0	0%
Non-Fuel	1	4%
TOTAL	15.6	100%

1 See Annex 1 for definition of UN/ECE Categories

Emissions of Manganese

Long term exposure to high levels of manganese can result in effects on the central nervous system such as visual reaction time, hand-eye coordination and hand steadiness. Exposure to higher levels over a long period of time can result in a syndrome known as manganism. This leads to feelings of weakness and lethargy, tremors and psychological disturbances.

Table 6.24 summarises the UK emissions of manganese. Estimates have been included in the NAEI for the first time and the figures are very uncertain. Emission factors have been calculated for the combustion of coal and heavy liquid fuels, but emission factors are not available for many industrial processes, with the exception of iron & steel manufacture and a few other processes, where emission estimates have been based on data given in the Pollution Inventory. Further development of the manganese inventory will occur in future versions of the NAEI.

Table 6.24 UK Emissions of Manganese by UN/ECE Category (Ktonnes)

	2000	2000%
BY UN/ECE CATEGORY^1
Comb. in Energy Prod.
Public Power	17	5%
Petroleum Refining Plants	0	0%
Other Comb. & Trans.	86	28%
Comb. in Comm/Inst/Res
Residential Plant	125	41%
Comm/Pub/Agri Comb.	20	6%
Combustion in Industry	21	7%
Production Processes	35	12%
Road Transport	0	0%
Other Trans/Mach	0	0%
Waste	0	0%
By FUEL TYPE
Solid	268	88%
Petroleum	0	0%
Gas	0	0%
Non-Fuel	35	12%
TOTAL	303.6	100%

1 See Annex 1 for definition of UN/ECE Categories

Emissions of Tin

Inhalation of dust and fumes may cause a disease of the lungs called stannosis.

Table 6.25 summarises the UK emissions of tin. Estimates have been included in the NAEI for the first time and the figures are very uncertain. Emission factors have been calculated for the combustion of coal and heavy liquid fuels, but no data are available for other potential sources such as industrial processes. Further development of the tin inventory will occur in future versions of the NAEI.

Table 6.25 UK Emissions of Tin by UN/ECE Category (Ktonnes)

	2000	2000%
BY UN/ECE CATEGORY^1
Comb. in Energy Prod.
Public Power	0	0%
Petroleum Refining Plants	0	0%
Other Comb. & Trans.	24	33%
Comb. in Comm/Inst/Res
Residential Plant	35	48%
Comm/Pub/Agri Comb.	6	8%
Combustion in Industry	5	6%
Production Processes	2	2%
Road Transport	1	1%
Other Trans/Mach	0	0%
Waste	2	2%
By FUEL TYPE
Solid	71	96%
Petroleum	1	2%
Gas	0	0%
Non-Fuel	2	2%
TOTAL	74.3	100%

1 See Annex 1 for definition of UN/ECE Categories

Spatial Disaggregation of Heavy Metals

All of the heavy metal emission estimates presented here have been spatially disaggregated with the exception of beryllium, manganese and tin, and UK maps are presented in Figures 6.13 to 6.22. The key features that are evident from the maps are briefly considered here:

Arsenic

Significant emissions arise from coal combustion, and consequently emissions in Northern Ireland are noted to be relatively high. Individual points sources are also evident.

Cadmium

The major source for 2000 arises from activities associated with non-ferrous metals. This proves difficult to identify from the UK map.

Chromium and Copper

The dominant sources of Chromium are coal combustion, iron and steel production processes, and chromium-based chemicals manufacture. In the case of copper, the main sources are coal combustion, iron and steel manufacture and non-ferrous metals production. From the UK emission maps it can be seen that there are a number of point sources, and elevated emissions in Northern Ireland for both of these pollutants.

Lead

In 1999 the majority of lead emissions arise from road transport activities, although a significant contribution comes from the non-ferrous metal industry. The major road network is clearly visible from the UK emission map indicating road transport as the dominant source sector.

Mercury

The major sources of mercury in 1999 were waste incineration, coal combustion and specific industrial activities. As a result the UK emission map highlights a number of point sources with a more widespread coverage.

Nickel

Emissions of Nickel are dominated by the combustion of coal and heavy fuel oil. Consequently areas of the country with refinery activities are highlighted. It is also interesting to note that urban areas are not elevated, with high population density areas often resulting in lower emissions per 1x1 km grid cell. This is due to the higher use of gas in the domestic sector in areas of higher population density.

Selenium

Emissions of selenium are dominated by the glass industry and coal combustion. Consequently the UK emissions map displays some major point sources, and other areas with very low emissions.

Vanadium

Vanadium emission primarily arise from the combustion of heavy fuel oils- in the refinery and industrial sectors. As a result a large number of point sources may be identified from the emissions map, and large conurbations/areas of high population density show low emissions.

Zinc

Zinc emissions primarily arise from combustion in the non-ferrous metals sector, iron and steel production processes and road transport (brake and tyre wear). As a result the UK emissions map highlights the road network and a number of point sources. However, the point sources are difficult to see due to the large number of grid cells that are impacted upon by emissions from the road transport sector.

Fig 6.20 Spatially Disaggregated UK Emissions- Arsenic	Fig 6.21 Spatially Disaggregated UK Emissions-Cadmium
Fig 6.22 Spatially Disaggregated UK Emissions Chromium	Fig 6.23 Spatially Disaggregated UK Emissions- Copper
Fig 6.24 Spatially Disaggregated UK Emissions of Lead	Fig 6.25 Spatially Disaggregated UK Emissions of Mercury
Fig 6.26 Spatially Disaggregated UK Emissions of Nickel	Fig 6.27 Spatially Disaggregated UK Emissions- Selenium
Fig 6.28 Spatially Disaggregated UK Emissions- Vanadium	Figure 6.29 Spatially Disaggregated UK Emissions of Zinc

Accuracy of Emission Estimates of Heavy Metals

Quantitative estimates of the uncertainties in emission inventories have been based on calculations made using a direct simulation technique, which corresponds to the IPCC Tier 2 approach recommended for greenhouse gases and also the methodology proposed in draft guidance produced by the UN ECE Taskforce on Emission Inventories. This work is described in detail by Passant (2002b). The uncertainty estimates are shown below in Table 6.26.

Table 6.26 Uncertainty of the Emission Inventories for metals

Pollutant	Estimated Uncertainty %
Arsenic	-40% to +70%
Cadmium	-20% to +30%
Chromium	+/- 20%
Copper	-20% to +40%
Mercury	-30% to +40%
Nickel	-30% to +40%
Lead	+/- 10%
Selenium	-40% to +70%
Vanadium	-50% to +80%
Zinc	-30% to +60%
Beryllium	-70% to +200%
Manganese	-80% to +300%
Tin	-90% to +300%

The inventories for beryllium, manganese and tin are still being developed and are currently much more uncertain than those for other metals.

Among the remaining metal inventories, those for lead and chromium are least uncertain, while those for arsenic, selenium, and vanadium are most uncertain. In the case of lead and chromium, these inventories are less uncertain probably because of the reliability of estimates for major sources such as road transport in the case of lead, and chromium chemicals in the case of chromium. The inventories for arsenic, selenium and vanadium seem to be most uncertain because of the high uncertainty in estimates of emissions for major sources including burning of impregnated wood (arsenic), flat glass production (selenium), and combustion of fuel oil (vanadium).