The city government says the strictest emergency measures will take effect when the pollution index for fine particulate matter, PM2.5, is forecast to exceed 300 micrograms per cubic meter for three days running.
Private vehicles will be allowed to operate on alternating days depending on the last number of their license plates. Factory emissions will be cut by 30 per cent through suspending or limiting production, and construction sites must halt excavation and demolition work.
Classes will also be suspended, a measure likely to cause inconvenience in a city where most parents both work.
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