Thirty-five restaurants in Beijing have been fined in the latest campaign against kitchen emissions.

Beijing Environmental Protection Bureau said on Monday it inspected 203 restaurants in densely populated downtown areas after receiving many complaints from the public.

Thirty-five of the restaurants were fined and ordered to rectify the problems, a statement from the bureau said.

The inspections showed that some of the restaurants failed to install outdoor emissions purification equipment, while some others failed to maintain this equipment properly.

In summer, kitchen emissions can contribute 15 to 20 percent of the PM2.5 pollutants in downtown Beijing, according to research in 2012 by Wang Yuesi at the Institute of Atmospheric Physics under the Chinese Academy of Sciences.