Beijing is tossing out its hazy Air Pollution Index and replacing it with a new Air Quality Index (AQI).

"The previous air monitoring statistics were too vague and differed from what residents felt," said Feng Yongfeng, founder of the Beijing-based environmental watchdog Green Beagle, on Sunday.

Feng praised the government's decision to switch to the AQI system, saying, "The government cannot escape from the true statistics, because the public demanded it for a year."

The Beijing Environmental Protection Bureau's announcement of the AQI on Saturday did not explain how the new index would be calculated, but noted that when it hit the 200 level ("serious"), safety measures kick in, including warning old people and children to limit outdoor activities. At 300 ("severe"), schools should cancel outdoor exercise. At 500 ("extreme"), all outdoor sporting events should be cancelled, and the government should cut 30 percent of the government vehicles on the road.

The name and scale of the new index suggest similarities to the AQI used by the US Embassy in Beijing.

The US readings, provided by the embassy every hour, have sparked a diplomatic complaint from the Chinese government. Differences between these readings and the Beijing government's have triggered discontent among the public.

For example, on Sunday evening, air quality was "very unhealthy" according to the US Embassy readings, but "slightly polluted" according to the Beijing Environmental Protection Bureau.

Until this year, the bureau did not even measure the tiny particles measuring 2.5 micrometers across (PM 2.5) that are most dangerous to human health because they can slip deep into the lungs.

Angered by this policy, last year Green Beagle started helping residents to monitor PM 2.5 levels and post results online.

Facing this kind of pressure, the bureau in October started to release statistics on PM 2.5 pollution levels. Many residents criticized that data because they believed the vague methodology minimized pollution risks.

Although environmentalists on Sunday praised the decision to use a new AQI, they were skeptical that the new measures, such as reducing the number of government cars on the road when pollution is extreme, would make much of a difference.

"Pollution is a regional problem, and it cannot be improved by eliminating the numbers of some vehicles," said Zhou Rong, an environmentalist from NGO Greenpeace. She also doubted the feasibility of the measure as the government failed to explain how to implement it as well as who will supervise it.