CARBON MONOXIDE EMISSION ESTIMATES

Carbon monoxide emission estimates

Carbon monoxide arises from incomplete fuel-combustion and is of concern mainly because of its effect on human health and its role in tropospheric ozone formation. It leads to a decreased uptake of oxygen by the lungs and can lead to a range of symptoms as the concentration increases.

The UK emissions of carbon monoxide are shown in Figure 4.6 and Table 4.9 disaggregated by source and fuel. Over the period 1970-1999 emissions decreased by 44% reflecting significant reduction in emissions from road transport, domestic and agricultural sectors.

Figure 4.6 Time Series CO Emissions

The spatial disaggregation of CO emissions is shown in Figure 4.7. The observed pattern of emissions is clearly dominated by road transport emissions. A large proportion of road transport emissions are from vehicles travelling at slow speeds on urban or minor roads, hence the map shows high emissions in urban conurbations.

Figure 4.7 Spatially Disaggregated UK Emissions of CO

Transport

The most important source of CO is road transport and in particular petrol driven vehicles. Emissions from road transport fell only slightly between 1970 and 1990 but in recent years have declined more significantly. This is due primarily to the increased use of catalytic converters and to a lesser extent to fuel switching from petrol cars to diesel cars. The emissions from off-road sources includes portable generators, fork lift trucks, lawnmowers and cement mixers. The estimation of emissions from such machinery is very uncertain since it is based on estimates of equipment population and annual usage time.

Table 4.9 UK Emissions of Carbon Monoxide by UN/ECE¹ Source Category and Fuel (kt)

	1970	1980	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	1999%
BY UN/ECE CATEGORY²
Comb. in Energy Prod.
Public Power	117	121	114	113	110	100	106	104	102	71	73	61	1%
Petroleum Refining Plants	7	7	6	7	7	7	7	7	7	7	8	7	0%
Other Comb. & Trans.	45	24	22	22	20	20	20	22	23	23	26	27	1%
Comb. in Comm/Inst/Res													0%
Residential Plant	1251	622	358	382	347	369	324	260	268	246	239	252	5%
Comm/Pub/Agri Comb.	46	26	22	22	21	21	20	19	19	19	18	18	0%
Combustion in Industry
Iron & Steel Comb.	220	63	108	102	106	105	97	98	98	100	102	105	2%
Other Ind. Comb.	142	82	79	75	75	74	76	72	65	66	55	68	1%
Production Processes	367	283	442	425	410	414	431	440	455	463	470	476	10%
Extr./Distrib. of Fossil Fuels	2	2	7	3	3	2	3	3	3	3	3	1	0%
Road Transport	5427	5378	5235	5072	4855	4525	4268	4003	3961	3726	3507	3293	69%
Other Trans/Mach
Off-Road Sources	588	519	438	454	462	448	438	417	419	419	420	419	9%
Other³	28	26	27	25	24	24	22	22	23	21	19	18	0%
Waste	3	45	31	28	27	27	35	25	25	20	21	17	0%
Land Use Change	288	449	266	228	165	4	0	0	0	0	0	0	0%
By FUEL TYPE
Solid	1697	847	610	628	593	596	542	476	474	429	423	420	9%
Petroleum	6082	5945	5717	5569	5358	5014	4744	4456	4416	4176	3956	3739	79%
Gas	43	35	40	40	43	49	54	56	61	58	60	65	1%
Non-Fuel	710	820	788	719	639	481	507	503	517	522	522	535	11%
TOTAL	8531	7647	7155	6956	6633	6140	5847	5492	5468	5184	4960	4760	100%

1 UK emissions reported in IPCC format (Salway, 2001) differ slightly due to the different source categories used.

2 See Appendix 4 for definition of UN/ECE Categories

3 Including railways, shipping, naval vessels, military aircraft

Other sources

Other emission sources of CO are small compared with transport and off-road sources. Emissions from the domestic sector have decreased by 80% since 1970 due to the decline in the use of solid fuels in favour of gas and electricity. The sudden decline in emissions from the agricultural sector reflects the banning of stubble burning in 1993 in England and Wales. Currently energy production accounts for only 2% of UK emissions.