Up to now, policy makers have mainly focused on particles of less than 10 microns diameter, known as PM10. New evidence of links between these particles and health problems such as asthma and allergies was presented at last year's major World Health Organisation conference on environment and health in London (ENDS Daily 15 June 1999). Meanwhile, the EU is close to finalising legal limits on PM10 concentrations in ambient air (ENDS Daily 13 January).
Research presented at yesterday's conference suggests that a new focus is now needed on particles ranging from 1 micron diameter down to as little as 10 nanometers (0.01 microns), according to Mr Ege.
One UK scientist suggested that there was no clear dose-response relationship between concentrations of these ultra-fine particles and health impacts, suggesting that harm might be caused at very low exposure levels. The same researcher claimed that waste incineration could be as large a contributor to emissions of ultra-fine particles as road traffic and especially diesel vehicles.
Meanwhile, a Danish environmental protection agency official suggested that particle filters on diesel vehicles might not be as efficient at trapping particles in the range of 10-20 nanometers as previously thought, and might even produce more of them.
Danish Ecological Council, tel: +45 33 15 09 77.
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