SHANGHAI: Enterprises within 300 km of Shanghai in the Yangtze River Delta will be subject to production control during the six-month World Expo if the city's air quality falls below standards, local environmental protection authorities said yesterday.

"We'll monitor air quality each day and if it shows negative trends, we'll take emergency measures, including production control or even shutting down certain heavy-polluting companies," Zhang Quan, director of the municipal environmental protection bureau, told China Daily yesterday on the sidelines of the annual municipal people's congress.

Iron, steel, chemical and construction industries will be subject to the rule. The policy has gained support from officials in nearby provinces including Jiangsu and Zhejiang, he said.