Health Effects of Carbon Monoxide
Information on effects
Health Effects
Exposure of humans to carbon monoxide can lead to raised levels of carboxyhaemoglobin in the blood, which replaces the normal oxygen carrier, haemoglobin, in red blood cells. Noticeable effects can occur when the level of carboxyhaemoglobin reaches 2.5% in blood. Carbon monoxide is a colourless and odourless gas that at extremely high concentrations can cause death. This normally would only occurring with faulty heating appliances in unventilated spaces. At lower concentrations physical ability such as hand to eye co-ordination can be affected. The main impairment is on the heart and brain, people with heart disease can experience more chest pain at increased levels of concentration. Smokers have elevated levels of carboxyhaemoglobin depending on the number of cigarettes smoked.
Sources
Carbon monoxide is produced during combustion of carbon based fuel. The major source in the outdoor environment in a London borough such as Hammersmith & Fulham is the motor vehicle, which produces in excess of 95% of the measured carbon monoxide. In the indoor environment the main sources are faulty gas appliances and cigarette smoke.
Standard
The standard to be achieved by 2005 is set at 10 parts per million measured as an eight hour rolling average.
Monitoring Results
Carbon monoxide has not been routinely monitored in the borough for some years. To estimate emissions, data from other sources can be used to infer likely concentrations in the borough. Monitoring has taken place at a number of sites across London. The DETR had a monitoring station on the Cromwell Road until August 1996 and still operates a station at Earl's Court. Data from both these sources are given in table 7 below. The information gathered from the two sites demonstrates that levels of CO have been falling for a number of years, which is consistent with the NAQS.
Table 7 Recorded levels of carbon Monoxide at the DETR's West London monitoring sites (measured as maximum 8 hour running average)
| YEAR | EARL'S COURT | CROMWELL ROAD |
| 1990 | 10.2 | 15.5 |
| 1991 | 15.8 | 13.9 |
| 1992 | 6.3 | 8.7 |
| 1993 | 8.7 | 9.1 |
| 1994 | 8.8 | 10.1 |
| 1995 | 11.1 | 6.7 |
| 1996 | 6 | n/a |
| 1997 | 8 | n/a |
All figures in parts per million.
Compliance with Standard
The NAQS states in Chapter II.5 that given current policies and measures in place then "national emissions of carbon monoxide will reduce by 32% in 2000, 48% in 2005 and by 54% in 2010 compared with 1995 levels." The strategy also predicts that the measured levels at the Cromwell Road site to fall to between 3.3 and 8.1 ppm as an 8 hour running average by the year 2005. Evidence from other monitoring stations in London has shown that the only exceedences of carbon monoxide have been in the winter and close to busy roads. Given the above information it is expected that the standard will be achieved for carbon monoxide by the year 2005 and no further assessment will be necessary.
