Health Effects of Ozone
Information on effects
Health effects.
Ozone is an irritant gas that can affect the eyes and nose. It can also damage the lining of the lungs and airways causing it to become inflamed and more sensitive. Short term exposure to high concentrations can lead to damage of the lungs, however, current guidance suggests there is no evidence to suggest that this is likely to lead to permanent damage. The effects of ozone on health are related to the levels of exposure, the time of exposure and the amount of activity during exposure.
Sources.
Ozone is described as a secondary pollutant, that is it is not directly emitted from vehicles or from industry but is produced by the interaction of strong sunlight with primary pollutants such as nitrogen dioxide and volatile organic compounds (VOCs). Ozone can take several hours or days to form and often the source is some distance from the area affected. A significant proportion of the ozone that affects the south east of England results from pollution in central Europe that is carried by prevailing winds. As ozone is a transboundary pollutant, effective local action to lower concentrations is not appropriate.
Standard.
The air quality standard to be achieved by the year 2005 is set at 50 parts per billion as a running 8 hour mean measured at the 97th percentile.
Monitoring results.
There has been no routine monitoring of ozone in the borough. Measurements undertaken at other sites within London in 1996 indicate that there are days when the standard set under the NAQS is exceeded. The London Bloomsbury site recorded 30 exceedences in 1996 and the London Kensington and Chelsea site (urban background) recorded 15. These figures indicate that the formation of ozone will continue to be a problem in the near future.
Compliance with the standard.
As it is not appropriate for the local authority to implement effective action against the production of ozone, compliance with the standard is dependent on national and European legislation to deliver any reductions in concentrations.
The NAQS states on page 138, paragraph 56 that "the reduction of ozone concentrations is difficult and requires a coherent European approach to achieve the best value for money in expenditure on abatement measures. While there is merit in the UK acting alone in that some reductions in peak levels will occur, maximum benefit will be obtained by a concerted approach with our neighbours. Emissions elsewhere in Europe appear to be roughly twice as important as those within the UK for reducing peak ozone levels."
The NAQS also highlights the comparatively stringent standard set on EPAQS recommendation. Paragraph 57 on page 138 says:
"The government recognises that the level recommended by EPAQS, while achievable in principle by reducing man-made emissions, would require extremely large reductions. Nonetheless, the government has decided to accept 50 ppb as a running 8 hour mean, as the air quality standard, defining the level of ozone at which effects on public health, including the most sensitive individuals would be small. The government further notes the comment of EPAQS that restricting the number of exceedences of the standard to 10 days or so per year at any one site would ensure that the maximum 8 hour values at that site would be unlikely to exceed 100 ppb, a concentration at which effects in healthy individuals have been clearly demonstrated."
The Air Quality Regulations 1997 specify that local authorities should not undertake to review and assess ozone levels with a view to declaring an Air Quality Management Area. Therefore it is recommended that no further assessment be made with regard to ozone concentrations within the borough's boundaries.
