Air pollution will continue to claim lives in Britain because the air quality targets set for 2005 and 2010 will not be met, Mike Pilling of the University of Leeds told the British Association meeting.

London will remain polluted with nitrogen dioxide and particles from traffic and other fossil fuel burning.

Roads and main urban centres are likely to remain unhealthy environments. Further problems will blow in from abroad, according to aircraft studies of drifting pollution.

He added: "There are also other changes occurring. Temperatures will increase.

"We saw a big episode during August 2003, a heat wave, and there were something like 2,000 deaths ascribed to that heat. It is clear that perhaps 700 of those were due to the reduction in air quality.

"Changes will take place in the chemistry in the next 60 to 70 years, and in addition we will see increases in the incidence of these heat waves.

"So by 2070 we will be seeing something like a 10-fold increase in heat waves of the sort we saw last year."

The government aimed to reduce concentrations of small particles of soot and oxides of nitrogen as if they were separate problems, but they should be treated together, he said: the pollutants interacted with each other, and even the abatement measures could interfere with each other.

Some measures to reduce nitrogen oxides might lead to increases in ozone, a toxic form of oxygen important in the stratosphere, but a health hazard in the lower atmosphere.

"We need to take these into account as we frame legislation," Professor Pilling said. "There are some complex processes occurring in the atmosphere."

Moreover, pollution was no longer a local problem: British environmental researchers on a flight in July recorded plumes of carbon monoxide from forest fires in Alaska.

"It's going all the way round the globe," Prof Pilling added. "The Americans suffer pollution from Asia, and we get pollution transported from the US to us. We are exporting to Asia.

"We are not just recipients, but it is clearly affecting the pollution that we experience in this country. We are still at an early stage of understanding what the effects are going to be."