The Shanghai Environmental Monitoring Center will issue an air pollution alert and implement an emergency plan to reduce emissions when the city's Air Quality Index (AQI) exceeds 200, the Shanghai Environmental Protection Bureau announced Monday.

With the goal of reducing the harmful effects of air pollution on public health, the Emergency Plan of Heavy Air Pollution is more concrete in its requirements to curtail industrial, vehicle and agricultural pollution.

The plan was drafted by the Shanghai Environmental Protection Bureau and 15 other organizations. It is based on a plan that was implemented during the 2010 World Expo in Shanghai.

The city's AQI has six tiers, each for a higher level of air pollution. Air pollution is considered unhealthy when the index exceeds 200. It is considered hazardous when it surpasses 300.

The pollution alert will be sent out via microblog, radio, television and mobile applications. Schools will receive their own updates as well.

Still, the alert will only be issued when pollution levels look as if they will remain high for a while, said Ren Juping, head of the bureau's pollution prevention and control department. "The alert will be issued when the forecast shows that pollution will not improve in the short term," Ren told Shanghai Television Station. "If the AQI is high in the morning but dips in the afternoon, it doesn't meet the criteria for an alert."

After an alert is issued, the emergency plan will go into effect. The plan requires large power plants to use low-sulfur coal and forces petrochemical, steel and concrete plants to reduce their emissions.

The plan also requires road maintenance and construction projects to shut down while the alert is in effect. The traditional burning of straw, which causes smog, is also prohibited.

"It's not going to make much of a difference if Shanghai is the only city to carry out the plan," said Dai Xingyi, director of the Urban Environment Management Research Center at Fudan University. "There are too many large power and chemical plants in the Yangtze River Delta. All of them are heavily polluting industries."

In addition to the industrial controls, the government will stop using 30 percent of official cars on heavy pollution days, and yellow-label cars, which are heavily polluting vehicles, are not allowed to go out.

Dai questioned whether the restrictions can actually reduce immediate pollution. "There's a delay in pollution. When the index shows heavy pollution, it is already too late to control it," Dai told the Global Times.