BEIJING -- A red alert, the most serious level, will be issued for air pollution in Beijing if the city's Air Quality Index (AQI) reaches 500, local authorities said on Monday.

The information office of the municipal government released an updated emergency response plan for severe air pollution, aiming to better address air pollution with minimal disturbance to people's lives.

According to the new plan, which will become effective on Dec 15, more gas-burning vehicles will be pulled off the streets when an alert is issued.

Li Kunsheng from the city environmental protection department said Beijing had about 5.7 million registered vehicles, which emit 500,000 tonnes of pollutants every year, contributing over 30 percent of the hazardous PM2.5 accumulated locally.

Schools and factories will be suspended or closed based on more detailed and flexible standards.

Besides, as part of the Beijing-Tianjin-Hebei integration effort, the air pollution alert system in the three adjacent municipalities and province will be synchronized as per the new version.

China has a four-tier warning system for severe weather, with red being the most serious, followed by orange, yellow and blue.

Beijing issued its first air pollution alert plan in 2012. The plan has played an effective role in alleviating pollution accumulation and protecting the public's health, said Fang Li, deputy director of the environmental protection department.