BEIJING (Reuters) – Steel mills, coke plants and coal-fired utilities in China’s second-biggest steelmaking hub Jiangsu will have to slash their production capacity as the provincial authorities have escalated smog alerts for the next three days.

Air pollution is expected to worsen from Nov. 27 until Nov. 30, triggering second-level orange smog alerts in the country’s four-level system, the Department of Ecology and Environment of Jiangsu Province said in a statement.

Heavy industry in Jiangsu will have to cut more of their production capacity by at least 50 percent from 30 percent, and stop transportation of raw materials during the orange-level alerts.

The eastern province had escalated the alerts on Sunday to “yellow level”, the third-highest in China’s pollution warning system, from the least severe “blue level”.

Concentration of lung-damaging PM2.5 particles reached 155 micrograms per cubic meter in Jiangsu’s provincial capital city Nanjing on Monday, according to data from China National Environmental Monitoring Centre, more than four times the state standard of 35 micrograms.

Northern China has also been blanked by heavy smog from last week, with at least 28 cities issuing orange-level alerts.