– As pollution darkened the skies above northern China this week, and Beijing declared its first red alert over the capital’s air quality, state-run news media gave anxious readers one more reason to worry about going outdoors.

Customs authorities in Shanghai have seized nearly 120,000 counterfeit surgical masks, the official China News Service reported Thursday. Such masks have become an increasingly common sight in China, with more people wearing them in an effort to protect themselves from pollution.

Although the report suggested that the counterfeit masks, seized in two separate raids, had been intended for export, many wondered whether their own masks were authentic.

The report said that the seized masks — which bore the logo of 3M, the manufacturer of one of the most popular models of masks in China — were made with inferior materials and that they would offer no protection from pollution. In fact, the report said the masks would actually pose an added health threat for users, though it did not explain how.

New York Times