BEIJING - Starting Tuesday, real-time air quality monitoring data on PM2.5 intensity in China's 74 major cities is available at the website of www.cnemc.cn.

The move is considered a big improvement in air quality monitoring, made at the strong request of the public.

Information on particulate matter in China used to be limited to PM10, or particulate matter 10 microns or less in diameter.

There has been public demand in recent years for data on PM2.5, a gauge that monitors fine particulate matter with a diameter of 2.5 microns or less. It is considered to be more hazardous to people's health.

A total of 496 monitoring sites have been set up in the 74 cities.

According to data released by the Beijing Municipal Environmental Monitoring Center, overall air quality of Beijing at 4 pm Tuesday ranked "level II" or "fairly good", with an average air quality indices (AQI) reading of 67.

The PM2.5 pollution reading in southwest Beijing's Fengtai district and southern suburb Daxing district were marked at 111 and 176 respectively, or "slight pollution" and "medium pollution."

Data was collected from more than 20 monitoring sites across the capital city and will be updated every 15-40 minutes.

PM2.5 intensity and other air quality information in these 74 cities can also be available through mobile phones.

China is proceeding with its urban air quality monitoring program in stages and aims to make it cover all prefecture-level cities by 2016.