TIANJIN, Jan. 7 (Xinhua) -- Northern China's Tianjin Municipality saw PM2.5 levels plummet during the past year thanks to effective pollution control, local authorities said Monday.

The average density of PM2.5, fine particulate matter that causes smog, dropped to 52 micrograms per cubic meter, down 16.1 percent compared with the previous year, according to the city's environmental protection bureau.

The city had 10 heavily polluted days last year, 13 less compared with 2017.

Average concentration of sulfur dioxide, PM10 and nitrogen dioxide all dropped compared with the previous year, the bureau said.

The improvement was a result of a series of well-targeted measures, such as promoting clean energy heating, monitoring emissions from factories and the demolition of coal-fired boilers.

The nearby capital city of Beijing saw less heavily polluted days and a reduced average concentration of particles in 2018, local authorities announced earlier this month.