Changes in atmospheric conditions expected.

The UK will not reach EU targets for reducing air pollution, according to Mike Pilling, chair of the government’s Department for Environment Food and Rural Affairs (Defra) air quality group.

Pilling, an atmospheric chemist at the University of Leeds and director of the Distributed Institute for Atmospheric Composition (Diac), part of the Nerc Centres for Atmospheric Science, highlighted the problems faced by the country at this year’s British Association for the Advancement of Science’s Festival of Science held in Exeter, UK. Ozone levels in the troposphere are too high, and the same is true for NO and particulates, he says.

In the UK heatwave of 2003, notes Pilling, there were an estimated 700 fatalities attributed to altered air quality. The climatic conditions were also linked to the emission of isoprene, which reacts very quickly with NOx to form ozone. This isoprene is released from broad leaved trees when temperatures soar above 30?C, and is part of a change in atmospheric chemistry that Pilling predicts will occur over the next 60 or 70 years . ’This occurs all the time in the US where they have lots of vegetation and high temperatures, but it’s not normally as substantial in the UK as it was last year’, Pilling told Chemistry World.

In turn, this will be accompanied by stratospheric cooling, he adds, ’that will influence chemical reactions and lead to an increase in ozone [in the stratosphere], which is a good thing’. So, extra ozone in the troposphere (nearest to earth): bad; ozone in the stratosphere: good. However, some ozone from the stratosphere is brought down into the troposphere: bad.

As for NO and particulates, Pilling concedes that levels are falling. ’Air quality is undoubtedly improving, but we’re not going to meet the [EU] objectives,’ he said. ’Human health is undoubtedly going to suffer.’ Particulates being measured at the moment are in the 10 ?m diameter range, but as particle size decreases, the detrimental effect on human health increases. Targets for particulates of about 2.5 ?m diameter have not been set.

Pilling is involved in policy formulation, with his responsibilities at Defra and Diac, and is impressed that Defra is focused on improving air quality and ’committed to trying to meet the objectives that have been set on health grounds’. But he has to reconcile this with his day-job as a research chemist. ’We’re trying empirically to predict what the [NO, particulates and ozone] concentrations will be. It’s a very complex problem. If you’re going to develop policy you can’t wait for the ultimate answer . as a university scientist I feel that one of the things we’ve got to do is understand what’s going on so that in the longer term we can build models that will help to understand what we need to do in order to improve air quality and to ameliorate climate change.’

Responsibility for reducing emissions lies with both industry and the UK population as a whole. ’There’s got to be a balance between the cost [of developing measures to address pollution and emissions] and the air quality that we want to have’, concluded Pilling. ’We obviously can’t have zero emissions because it would cost too much’.

Katharine Sanderson/Exeter, UK