In July, an airflow study will be conducted in the subways by a national lab, the MTA and NYPD. A fake poster warning of the event has been spotted underground.
An NYPD detective tells PIX11′s Greg Mocker that an official notice will be put out to the media.
The MTA has instructed crews to remove the posters in the system.
The poster, featuring a man in a gas mask and advice to stay calm, has also been circulating online.
The study is designed to see how airborne contaminants — released accidentally or on purpose — would work their way through the system.