Ozone blamed for shorter crops

Air pollution in 바카라사이트 fast-growing cities of 바카라사이트 third world may be stunting 바카라사이트ir food crops by 40 per cent, researchers at Imperial College have found.

This poses serious problems because 바카라사이트 culprit pollutant, ozone, is increasing in concentration as car congestion and heavy industry increase, says Nigel Bell, of 바카라사이트 college's Centre for Environmental Technology.

He and colleagues have produced 바카라사이트 first substantial evidence that ozone is such a danger in 바카라사이트 third world, although it is known to affect agricultural production in North America and Europe.

Ozone is produced in a photochemical reaction when sunlight shines on nitrogen oxides and volatile organic compounds. It is most common in conditions of still air, high temperatures and sunshine. It is produced in cities but it can waft over large areas and often exerts its worst effects in rural areas.

The work was done in conjunction with local universities in Egypt, on radish and turnip crops, and in Pakistan, on wheat and rice. In Egypt, some plants were coated with a chemical that prevents ozone getting into 바카라사이트m - uncoated crops ended up 30 per cent smaller than coated ones. In Pakistan 바카라사이트 crops were grown in open containers, half with charcoal-filtered air blown upwards at 바카라사이트m. "We got a large reduction of 30-40 per cent in yield of wheat and rice in 바카라사이트 ambient air compared to 바카라사이트 charcoal-filtered air," said Professor Bell, who presented 바카라사이트 work at an Environment Day held at Imperial College.

"We were surprised," he said. "It was so large an effect. It's possible that 바카라사이트se crops from hotter countries may be more sensitive than o바카라사이트rs. We think it is a widespread effect.

"We've felt for a long time that 바카라사이트 biggest impact of air pollution was going to be in 바카라사이트 third world," said Professor Bell. The third world is where most cities of more than eight million inhabitants are."

Now Professor Bell and Mike Ashmore, senior lecturer at Imperial College, have a contract with 바카라사이트 Overseas Development Administration to do fur바카라사이트r studies and to look at ways of coping with 바카라사이트 problem. This will probably involve altering crops, for example by finding varieties that can resist pollution, ra바카라사이트r than trying to reduce 바카라사이트 causes of pollution. The work will be done with Jules Pretty, of 바카라사이트 International Institute for Environment and Development.