The NYPD will study how chemical gases might dissipate in city subways underground in a possible terror attack.
The test, conducted with the U.S. Department of Energy’s Brookhaven National Laboratory, will be the largest-ever study of the risks of airborne contaminants.
- PHOTOS: Celebrities attend 'Avengers: Endgame' premiere in Los Angeles22 Pictures
- PHOTOS: Memorial spotlights the man behind Nipsey Hussle rap persona14 Pictures
During three separate days in July, researchers will disperse harmless gases in 21 subway lines and at street level, tracking how they disperse.
Researchers said they will release the gases in the Bronx, Brooklyn, Queens, Staten Island and Manhattan from 59th Street to the Battery.
The gases will be perfluorocarbons, which pose no health or environmental threat, according to the NYPD.
Ultimately, the NYPD will use the data to decide how to best respond in such an emergency.
“The NYPD works for the best but plans for the worst when it comes to potentially catastrophic attacks such as ones employing radiological contaminants or weaponized anthrax,” Kelly said.