Pollutant Information: Carbon Monoxide 

About Carbon Monoxide

Category: Air pollutants

Carbon monoxide (CO) 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. Road transport, in particular vehicles with petrol engines, is the largest source of carbon monoxide emissions, although domestic fires, the iron and steel sector, and industrial fuel combustion are also significant. Emissions from road transport have decreased by 93% between 1990 and 2015 as a result of EU-wide emission standards, and the importance of the road transport sector has declined as a result – from 64% of CO emissions in 1990 to just over 20% in 2015. Combustion-related emissions from the domestic and industrial sectors have decreased by 89% and 65% respectively since 1970 due to the decline in the use of solid fuels in favour of gas and electricity. The banning of stubble burning in 1993 in England and Wales caused a sudden decline in emissions from the agricultural sector from 1994 onwards. Over the period 1970-2015, emissions have decreased by 82%.

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Time series graph


Notable events

Start year End year Sector Information Impact
1993 1993 Agriculture Field burning of agricultural waste stopped after 1993. Decrease in emissions
1970 1985 Iron and Steel Decline in the energy intensive iron and steel industry and other heavy industries. Decrease in emissions
1992 2011 Road Transport Stricter Euro I - V emission regulations come in on trucks and buses offsets increasing vehicle km. Impact takes time to bite as only new vehicles need to meet standards. Decrease in emissions
1992 2014 Road Transport Stricter Euro I - 5 emission regulations come in for cars offsets increasing vehicle km. Impact takes time to bite as only new vehicles need to meet standards. Decrease in emissions
1986 2011 Residential Combustion Decline in the use of solid fuels (use of coal for domestic combustion has been restricted in the UK by the Clean Air Acts) in favour of gas and electricity. Decrease in emissions
1990 2011 Stationary Combustion Deregulation in the use of gas for electricity production. Increased use of Combined Cycle Gas Turbine (CCGT) stations and other gas fired plant rather than coal for electricity generation. Decrease in emissions

Carbon Monoxide contributes to the following...

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