BEIJING - Beijing issued a yellow alert for heavy air pollution Tuesday as a new round of smog hit the city, authorities said.

The alert indicates an air quality index of over 200, or over 150 micrograms of PM 2.5 per cubic meter of air for two consecutive days, was issued at 10 a.m., according to a statement by the city's air pollution emergency response office.

Air quality will improve around noon Thursday, according to the statement.

Outdoor construction will be limited, while more road cleaning will be conducted.

Beijing has a four-tier color alert system for pollution, with red the highest, followed by orange, yellow and blue.

Smog is also predicted in large parts of northern China on Tuesday and Wednesday.