Health Effects of Sulphur Dioxide
Information on effects
Health Effects
Sulphur dioxide is an acidic gas at normal room temperature and pressure. Due to its acidic nature it is an irritant when inhaled. The health effects resulting from the inhalation of Sulphur dioxide are rapid. The adopted standard of 100ppb measured as a percentile is expressed as a 15 minute measure. This is to reflect the rapidity of the effect of inhalation on vulnerable groups. EPAQS have stated at high concentrations it can cause breathing difficulties and studies have shown that at the levels which occur during pollution episodes this may be sufficient to provoke an attack in asthma sufferers.
Sources
The major source of Sulphur dioxide in the UK is from the burning of fossil fuel for power generation on a commercial and domestic basis. Overall emissions are dominated by a small number of large point sources. In 1995 44% of all sulphur dioxide emissions arose from nine power stations (NAQS chapter II.10 paragraph 4). Since the introduction of the clean air acts in the 1950s concentrations have fallen dramatically in the urban environment as fewer people burn coal for domestic heating. The contribution from road traffic to levels of sulphur dioxide in the air is very small on a national basis. However in an urban environment such as Hammersmith & Fulham the contribution is much greater with an estimated 23% of all emissions resulting from traffic movement, especially from the use of diesel fuel.
Standard
The standard to be achieved by the year 2005 has been set at 100 ppb at the 99.9th percentile of 15 minute means. This standard reflects the concern of short term exposure to high levels of sulphur dioxide. The use of a 99.9th percentile means that the standard for Sulphur Dioxide must be met for 99.9% of the time.
Monitoring results
There has been no recent monitoring of sulphur dioxide in the borough. Routine monitoring was stopped at the request of the Department of Environment when levels fell below the then current threshold. The current guidance from the DETR says that areas with emissions greater than 40 tonnes per annum would require further review and assessment.
Compliance with the standard
The major local source of Sulphur Dioxide is from motor vehicles. Lots Road power station in the Royal Borough of Kensington & Chelsea has the potential to impact on the southern part of the borough. However, this power station will not be operational in 2005. Industrial activity in the East Thames region can cause elevated levels in West London when weather conditions permit. As only a very small number of exceedances of the standard are permitted it will be necessary to progress to a stage 2 assessment of Sulphur Dioxide to establish the likely number of days where the standard is breached.
