Experts at the Health Protection Agency say that current methods of reporting the health effects of air pollution are outdated and need to be reviewed if they are to more accurately reflect environmental risks in the 21st century.

The issue is being discussed at the HPA's annual conference - Health Protection 2010 - at the University of Warwick today.

Professor Robert Maynard, head of air pollution at the HPA, says that it would be more appropriate to express the health effects of long-term exposure to air pollutants in terms of years of life lost rather than number of deaths.

It was different in the Fifties when the direct links between air pollution and deaths were much clearer - for example the 1952 Great Smog of London which enveloped the city in a four day 'pea souper' was estimated to have caused 4,000 deaths. This led directly to the Clean Air Act of 1956.

But despite a huge improvement in air quality since the Fifties, recent scientific studies suggest that long-term exposure to fine particles - of less than 2.5 micrometres in diameter called PM2.5 - are associated with an increased risk of death from heart disease at all adult ages. And in March, the Government's Environmental Audit Committee reported that long term exposure to air pollution may be a contributory factor in the deaths of between 35,000 and 50,000 people each year in the UK.[1]

Speaking at the HPA conference today, Prof Maynard said today's figures could not be compared with the 1952 London smog.

He said: "Calculations that suggest that as many as 35,000-50,000 deaths per year can be attributed to long-term exposure to fine particles are correct arithmetically but require careful interpretation. It is not possible to calculate how many years of life that an individual has lost, but it is possible to estimate the average loss of life expectancy for the whole population."

Using this method, the average predicted loss of life expectancy at current levels of fine particulate air pollution is 6 months. Professor Maynard added: "This approach is sounder and less beset by problems of interpretation. It is the method for the 21st Century."

Notes

COMEAP: Long term exposure to air pollution: effect on exposure: see here

1. Environmental Audit Committee - Fifth Report: Air Quality

Source:
Health Protection Agency