HONG KONG - Hong Kong's catering and fitness groups have launched an unprecedented petition campaign to fight the city's worsening air pollution.

Starting this month, more than 200 leading restaurants, cafes and gyms in the city will invite their customers to sign 'The Petition for Clean Air.'

The organisers also ran campaign ads in the International Herald Tribune and several local newspapers this week, reminding readers that Hong Kong's air pollution 'kills three people a day' and its air is 'three times dirtier than New York City's.'

'It was the first time for Hong Kong to have a clean air campaign mounted by a large group of businesses,' Kwong Sum-yin, campaign manager of Clean Air Network, the NGO which coordinated the petition drive, said on Friday.

'We have often tried to engage members of the public in our previous campaigns. But we believe the involvement of business groups is equally important if we want to send the message across all sectors of the society.'

Businesses involved include Starbucks, Pacific Coffee, Ben & Jerry's, and Pure Fitness.

Kwong said their original plan was to run the campaign for six weeks. But she said it may be extended as other restaurants have also asked to join. The petitions collected will be presented to the government later this year.

Hong Kong's air pollution continues to worsen, with the city wrapped in a thick blanket of haze for most days in recent months.

Statistics from the Hong Kong Observatory show that the annual number of hours of 'reduced visibility", which refers to visibility of less than eight kilometres (five miles) in the absence of fog, mist or rain, jumped from 295 in 1988 to 1,139 in 2009.

Roadside air pollution in the city's Central district reached life-threatening levels one in every eight days last year, the South China Morning Post said, citing figures obtained from the government.

Critics said the problem has caused a huge economic and public health impact on society and driven talented people away from the international financial hub, with an increasing number of families - especially expatriates with children ' relocating elsewhere.

Authorities often blamed the deteriorating air quality on emissions from the southern Chinese factory belt over Hong Kong's northern border.

But a study conducted by the Civic Exchange think-tank last year showed that Hong Kong's own road emissions were the dominant source of air pollution.