Meeting EU targets for fine particulates (PM2.5) in the air will “remain challenging” without government action, according to a report for the Environment Agency, Scottish Environment Protection Agency and the Northern Ireland Environment Agency published in January.
The agencies commissioned the Scotland and Northern Ireland Forum for Environmental Research (SNIFFER) to look at the pollutant’s health effects, sources, regulation, monitoring and policy implications.
SNIFFER finds that to meet EU and UK targets to reduce urban background PM2.5 levels by 10-15% by 2020 (ENDS Reports 391, p 52 and 395, p 52), an average cut of 1.5-2.0 micrograms per cubic metre will be needed.
The cuts are based on PM2.5 levels of 12-16µg/m3 at most of the 27 urban monitoring stations detected in 2009. Rural background levels were 3-6µg/m3 lower.
While the cuts may appear small, the wide range of PM2.5 sources mean several policies are needed to tackle the pollutant.
Industry, power stations and road transport account for the bulk of direct emissions (see figure), although much is formed from atmospheric chemical reactions.
These ‘secondary particulates’, mostly ammonium salts and organic particles, account for 30-50% of the PM2.5 load in urban areas, says the report. A large proportion is generated from precursor emissions blown in from continental Europe.
If reductions are to be obtained by cutting locally generated emissions, the report says actual cuts of 25-67% would be needed within ten years to meet the targets.
Similarly, if cuts are to come solely from secondary particulates, the reduction would need to be 25-50%. Furthermore, “greater reductions in precursor gas emissions are required than might at first sight be the case” because they would not reduce PM2.5levels proportionately.
Whichever option is prioritised, the problem is “substantial”, says the report.
Before a EU-wide control strategy can be developed, SNIFFER says research is needed to define the sources of urban background emissions so the likely changes in emissions to 2020 can be assessed.
And at least seven more rural monitoring stations are needed, SNIFFER argues.
The environmental agencies can contribute by assessing emissions from the industrial agricultural and waste activities they regulate, the report adds. Local councils should consider ways to control emissions from new developments.
Councils should also help amend the Clean Air Act to control biomass boilers emissions, SNIFFER concludes. The legislation is widely seen as outdated (ENDS Report 407, pp 23-24).
The report also finds that the UK is unlikely to breach the EU annual mean limit value of 25µg/m3 for PM2.5, which enters force in 2015. The highest level measured in 2009 was 17.6µg/m3, in Eltham, south-east London, and urban levels are declining slowly.
Regarding the health impacts of PM2.5, SNIFFER finds it causes more damage to health than road traffic accidents or passive smoking. Both short-term and chronic exposure increase hospital admissions and mortality from cardiopulmonary disease (ENDS Report 432, pp 20-22).