"We have conducted research on this indicator and will release the monthly forecast on it," Song Lianchun, chief of the National Climate Center, said.

 

"Atmospheric environmental capacity" is a special indicator that demonstrates the carrying capacity of PM2.5 - airborne particles smaller than 2.5 microns in diameter that can penetrate the lungs and cause serious harm to health - in the air of a specified region.

 

If the annual capacity is lower than 0.5 of a ton per square meter, the possibility of heavy air pollution is quite high, thus making it another major indicator in the air pollution forecast.

 

Statistics show that the atmospheric environmental capacity of three major industrial regions - the Beijing-Tianjin-Hebei trilateral zone and the Yangtze and Pearl River deltas - has continued to decline over the past 60 years, Song said.

 

The Beijing-Tianjin-Hebei zone has the largest reduction in such capacity among the three, he added.

 

The air pollution forecast has become increasingly important because governments need it to implement emergency measures in advance.

 

However, it's not easy to be accurate because the weather forecasts involve complicated factors including changing pollution sources.

 

With more accurate air pollution forecasts warning of severity in three to five days, governments would have more time for better, more efficient preparation, said Yu Jianhua, director of air pollution under the Beijing Environmental Protection Bureau.

 

However, current forecasts of air pollution in the three days ahead cannot give an accurate level of air quality, but rather a trend for cities.

 

Xie Shaodong, a professor of environment at Peking University, and two other experts founded a free online platform in June to give forecasts of air pollution for three days ahead. It has received much positive response on its accuracy from experts as well as the public, Xie said.