TIANJIN -- North China's Tianjin Municipality saw PM2.5 plummet over the past six months thanks to effective pollution controls, local authorities said Friday.

The average density of PM2.5, fine particulate matter that causes smog, in Tianjin dropped to 63 micrograms per cubic meter between October and March, down 33.7 percent year on year, according to the city's environmental protection bureau.

The number of heavy pollution days decreased to 10 during the same period, down 71.4 percent year on year.

Yang Yong, an official with the bureau, said that Tianjin, which neighbors Beijing, recorded its best air quality since it started monitoring PM2.5 density.

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