Several Chinese celebrities have joined an online campaign aimed at pressuring the government into improving the way it measures air pollution, as residents increasingly worry about their health.

The campaign comes as locals in Beijing -- one of the world's most polluted cities -- have started to question a discrepancy between US embassy readings of air pollution in the capital and official data that is often milder.

Real estate tycoon Pan Shiyi initiated the drive at the weekend, calling on netizens to vote on whether authorities should start using a system that measures levels of tiny air particles, considered most dangerous to the health.

Pan posted the vote on his Twitter-like Sina Weibo account -- followed by more than 7.4 million people -- and it was reposted by other celebrities including Lee Kai-Fu, former head of Google China, and Yao Chen, an actress.

"Encourage more people to participate and protect the environment that we live in," wrote Ren Zhiqiang, another Chinese property mogul, who also reposted the voting call on his microblog.

More than 37,700 netizens have voted so far, with 92 percent saying the government should introduce a so-called PM2.5 standard this year, which measures particles under 2.5 micrometres in size.

Pan said he would collect the vote results and send them to China's Ministry of Environmental Protection to pressure authorities into changing their pollution data.

Particulate matter, or PM, is a type of pollution that floats in the air.

China currently uses PM10 as a measurement -- or particulate matter under 10 micrometres. But scientists say Beijing's pollution is mostly caused by fine particles under 2.5 micrometres, which the US embassy uses for its readings.

PM2.5 are widely seen to be more dangerous for the health, as they can pass through smaller airways and penetrate deeper into the lungs.

The different gauges often create a data discrepancy. When smog blanketed Beijing on October 30, for instance, the embassy's readings rated Beijing's air as "hazardous" while official measurements said the pollution was "slight."

As such, Beijing authorities have been accused of massively underestimating pollution in the Chinese capital, and a growing number of local residents are turning to the American figures rather than the official ones.

The Beijing Municipal Environmental Protection Bureau has pledged to improve the way it measures air quality, adding it is capable of monitoring smaller particles but that no timetable had been set for the release of these figures.