Shanghai will use a more flexible air quality warning system with a new emergency response to better combat pollution.

A red alert, the most serious level of the four-tier warning system in China, will be issued if the city's Air Quality Index (AQI) reaches 400, according to the Shanghai Environmental Protection Bureau.

Previously, the red alert was triggered when AQI passed 450.

If AQI is expected to temporarily exceed 200 within 24 hours, a blue alert will be issued.

And an orange alert is on if AQI is between 301 and 400 in the next 24 hours, or between 201 to 300 over the next three days, rather than between 301 to 450 in 24 hours previously.

High-polluting industries, such as steel, cement and printing, are requested to cut production during heavy pollution. Fireworks, outdoor barbecues and burning of garbage are banned under any of the four alerts.

(Xinhua News Agency December 14, 2016)