Hebei province on Thursday issued this year's first red alert for a three-day bout of severe air pollution.

The pollution is forecast to last from Friday to Sunday in eight cities, according to a notice released by the province's Air Pollution Prevention and Control Office.

A red alert is the most serious level for air pollution in a four-tier warning system, followed by orange, yellow and blue. It is issued when the city's Air Quality Index is predicted to reach 500.