Carbon monoxide in the Royal Borough

Monitoring

Carbon monoxide is monitored using the gas filter correlation method which is based on the absorption of infra-red radiation. The technique works by measuring the difference in the intensity of the radiation emitted by a cell of pure nitrogen and nitrogen plus carbon monoxide to determine the levels of carbon monoxide.

Carbon monoxide is monitored at:

North Kensington
West London
Cromwell Road

For information on the sources and health effects of nitrogen dioxide pollution, see Sources and health effects of air pollution.

You can get the latest readings or historical data for these sites at www.airquality.co.uk.

Long term trends

Carbon monoxide has been monitored at a number of locations in the Royal Borough since 1990.

Annual mean levels of carbon monoxide

Annual mean carbon monoxide levels - milligrams/cubic metre (mg/m³)
Year	North Kensington	West London Earls Court	Cromwell Rd 2	Cromwell Rd	Marylebone Rd
1990		1.74		3.36
1991		1.97		3.83
1992		1.28		2.67
1993		1.04		2.67
1994		0.93		2.20
1995	0.81	0.81		2.09
1996	0.58	0.70		1.51
1997	0.58	0.70			3.02
1998	0.46	0.46	1.51		2.32
1999	0.46	0.35	1.51		2.09
2000	0.54	0.43	1.40		2.32
2001	0.46	0.35	1.16		1.74
2002	0.35	0.35	1.04		1.39
2003	0.46	0.40	0.90		1.30
2004	0.50	0.40	0.81		1.16

The annual mean levels have declined since the early 1990s and appear in the last few years to be flattening out.
This trend is also the case for other sites within London, for example the Marylebone Road site which has shown a decline in the levels of carbon monoxide since 1997.
The objective levels have not been exceeded in the Royal Borough since 1995.