The following report constitutes the eleventh annual report from the UK National Atmospheric Emissions Inventory (NAEI). This report has been produced as part of the Department of Environment Transport and the Region's Air Quality Research Programme by the National Environmental Technology Centre.
Pollutants - This report presents the latest estimates of emissions to the atmosphere from the UK for the period 1970 to 1997 in a UN/ECE format where appropriate. The total number of pollutant species included in the 1997 annual inventory is 33- however this includes six pollutant groups (NMVOC, PCDD/F, PAH, PCB, HFC and PFC). Of these pollutant groups speciation is available for NMVOCs and PAHs, giving individual emissions of the 500 most significant NMVOCs and the 16 PAHs identified as "priority pollutants" by the USEPA. The pollutants considered are:
- carbon dioxide, CO2
- methane, CH4
- sulphur dioxide, SO2
- nitrogen oxides, NOx
- non-methane volatile organic compounds, NMVOC and associated speciation
- carbon monoxide, CO
- black smoke
- PM10 , PM2.5 , PM1 , PM0.1
- ammonia, NH3
- nitrous oxide, N2O
- dioxins and furans (PCDD/F)
- polyaromatic hydrocarbons (PAH)
- polychlorinated biphenyls (PCB)
- hydrofluorocarbons (HFC)
- perfluorocarbons (PFC)
- sulphur hexafluoride
- pesticides
- lindane
- hexachlorobenzene
- pentachlorophenol
- heavy metals:
- lead, Pb
- cadmium, Cd
- mercury, Hg
- copper, Cu
- zinc, Zn
- nickel, Ni
- chromium, Cr
- arsenic, As
- selenium, Se
- vanadium, V
- hydrogen chloride, HCl
CO2 - Emissions of CO2 from the UK show an overall decrease from 183 Mt in 1970 to 148 Mt in 1997. The most significant reduction is from the public power sector; reductions are also observed from the industrial combustion sector. Road transport emissions indicate a small increase on the 1996 emission estimates. Since 1990 total emissions have declined by 7.5%.
CH4 - Estimates of methane emissions show a decline from 3.77 Mt in 1970 to 2.73 Mt in 1997. The largest sources are landfills, agriculture, natural gas distribution and coal mining. The reduced emissions are primarily due to the decline in the coal mining industry- in addition, increased levels of methane recovery are now present on landfill sites. The uncertainties associated with the emission estimates of methane are high.
SO2 - UK emissions of sulphur dioxide have fallen from 6.34 Mt in 1970 to 1.66 Mt in 1997. This is a result of reduced emissions from the industrial and public power sectors arising from the decreasing use of coal, and increasing use of abatement equipment. However, coal combustion still accounts for 68% of the 1997 UK SO2 emissions.
NOx - UK emissions of NOx were 2.43 Mt in 1970, and 2.67 Mt in 1990. However emissions have fallen significantly to 1.83 Mt in 1997, representing a 31% reduction on the 1990 emissions estimate. This is primarily a consequence of: abatement measures in road transport, abatement measures in coal fired power stations and the increased use of other fuels for power generation. Road transport and coal combustion still account for 66% of UK emissions in 1997.
NMVOC - UK emissions of NMVOC are estimated as 2.40 Mt for 1970, 2.73 Mt for 1990 and 2.13 Mt for 1997. Reductions from 1990 to 1997 arise primarily from the road transport and industrial sectors. Although the estimates are of improved quality they are still very uncertain.
CO - UK emissions of CO are dominated by those from road transport (75% of UK emissions in 1997). Emissions in 1997 (5.09 Mt) represent a 43% reduction on the 8.85 Mt emission in 1970 and a 33% decrease on the 1990 emission of 7.57 Mt. The change in emissions between 1990 and 1997 is dominated by the reduction in emissions from the road transport sector, caused by the increased use of catalytic converters in cars.
PM10 - The UK emissions of PM10 declined from 0.51 Mt in 1970 to 0.18 Mt in 1997. This reflects a trend away from coal use particularly by domestic users. However, more recent increases in road transport and particularly diesel road transport have off-set a more dramatic decline in PM10 emissions. Coal use and road transport contribute 55% of UK emissions of PM10 in 1997.
BS - Black smoke emissions in the UK declined from 1.07 Mt in 1970 to 0.31 Mt in 1997. This is largely due to a switch away from coal to solid smokeless fuels and natural gas by domestic users. The reduction in emissions from domestic sources has been partially offset by an increase in emissions from diesel engined vehicles
N2O - UK emissions of nitrous oxide were 0.192 Mt in 1997. Emissions of nitrous oxide are dominated by agricultural emissions and the production of nylon and nitric acid. Reductions have primarily arisen from the production processes sector.
NH3 - The total UK emission of ammonia for 1997 is estimated at 0.36 Mt, a slight decrease on the 1990 estimate of 0.38 Mt. The agricultural sector dominates the total ammonia emissions, and the reductions more than offset the increased emission from the road transport sector.
Pb - UK Emissions of lead have declined sharply following reductions in the lead content of leaded petrol and the increasing use of unleaded petrol. Emissions in 1997 are estimated to be 1.31 kt compared with 7.54 kt in 1970. Road transport still contributes 61% of UK emissions in 1997. Emissions of other metals are also reported, and show a strongly declining trend.
HCl - UK emissions of hydrogen chloride have fallen from 0.33 Mt in 1970 to 0.09 Mt in 1997 largely as a result of declining coal use.
POPs - The 1997 UK emissions of persistent organic compounds may be summarised as follows: 1745 t PAH, 325 gTEQ PCDD/F (grammes of "toxic equivalence" of dioxins & furans) and 3.2 t PCB. Emissions from all three of these pollutant groups have greatly decreased. Emissions in 1997 equate to decreases of 73%, 70% and 53% on the 1990 emission, for PAHs, PCDD/Fs and PCBs respectively.
HFC,PFC and SF6- Estimates of emissions of halocarbons which contribute to global warming are discussed. 1997 UK emissions were 3.1 kt HFCs, 95 t PFCs and 53 t sulphur hexafluoride.
The 1997 emission inventory indicates that many of the total emission estimates for pollutants are dominated by emissions from road transport and the use of coal see table below.
