Beijing is to strengthen research on air quality forecasting with data from more monitoring stations to improve decisions taken to curb smog.

In the capital, 35 stations monitor air quality and upload the real-time data to the Environmental Protection Bureau.

To provide better information on air quality, the capital plans to raise the number of stations to more than 70 and increase the number of mobile monitoring vehicles to cover a wider area.

Smog forecasts help the municipal government to decide on the level of alerts it raises against air pollution. In December, for example, the city issued two red alerts - the first time it had adopted the highest-level response to air pollution. The alerts were issued based on air pollution forecasts from the Beijing Environmental Monitoring Center.

Qiu Qihong, a senior forecaster who has worked at the center for 15 years, said, "We can release an accurate forecast on air quality three days in advance with detailed information on pollution levels and also give a trend forecast for the coming 10 days."

He said that based on this trend information, the center can also give predictions on the air quality outlook for the next six months at most.

Beijing has carried out research on air quality forecasting since 1999 with cooperation from the local meteorological bureau.

Qiu said the capital started to release the forecasts in 2001, adding that the ability to forecast air pollution had served the city well and had been improved during the 2008 Olympic Games.

Sun Feng, another senior forecaster at the center, said the experience gained had been an important factor in improving the ability to provide accurate forecasts.

Xin Lianzhong, another senior forecaster, said forecasters make an analysis, combine the data with information on the weather and pollutant emissions, and release a pollution forecast every afternoon.

Li Shixiang, the city's deputy mayor, said, "Only when we have better monitoring data can we perform better in curbing smog in the capital."

After the center completes the forecasts, it sends them to the Environmental Protection Bureau, which informs the municipal government if severe smog is predicted.

Qiu said, "We hand in severe smog forecasts about a week ahead," adding that before the second red alert was issued on Dec 19 they had completed an accurate forecast five days previously.

But after this red alert was lowered on Dec 22, smog lingered for two days, making residents question whether it had ended too early.

All three senior forecasters said this showed that forecasting air pollution is never easy and can be affected by various factors, including changeable weather.