Campaigners claim the health of up to 34,000 people would be at risk if Gatwick airport expanded.

The Gatwick Area Conservation Campaign said a second runway would increase pollution from nitrogen dioxide, a gas which can cause respiratory problems.

Chairman Brendon Sewill said a group of businessmen was urging the Government to change its mind and build a new runway at the airport.

But he said a government report showed this would mean 4,000 people living near the airport would be exposed to a level of pollution from nitrogen dioxide, which was above EU guidelines.

Mr Sewill said: "It does not seem to have occurred to them the same level of pollution would also affect all 30,000 people who work at or near the airport.

"Gatwick with two runways would be as polluted as Heathrow is today and Heathrow is one of the most polluted places in the UK.

"Although nitrogen dioxide does not kill people, it affects those with respiratory problems, particularly asthma.

"The businessmen who have been pushing for another runway at Gatwick haven't taken into account the impact on the environment and health. They just think about profits."

A legal agreement signed between the airport and West Sussex County Council in 1979 forbids the building of a second runway before 2019.

Mr Sewill said the Government report, The Future of Air Transport in the UK, showed the building of another runway built after 2019 would mean 300 homes and many business premises on the north of Crawley would be knocked down.

Another 17,000 people, most from Crawley, would be affected by noise.