In April, the NYPD revealed it would release "harmless gases" into the subway system to test for "risks posed by airborne contaminants, including chemical, biological and radiological (CBR) weapons." The study will take place over three non-consecutive days this month and today is the first: In select subway stations across the city, you may see the NYPD accompanying researchers from Brookhaven National Laboratory installing equipment starting at 6 a.m.

According to the NYPD, "The sampling is scheduled to conclude by 3:00 p.m. The remaining two days of research, subject to weather conditions, will be announced 24 hours in advance. Air sampling will be conducted in parts of the Bronx, Brooklyn, Queens, Staten Island and in Manhattan. In addition, researchers will disperse low concentrations of harmless gases known as perfluorocarbons at several subway and street-level locations in Manhattan for 30 minutes only during the morning of each study day."

Brookhaven National Laboratory has more kind-of-vague details—it will include "21 subway lines and several dozen stations citywide, in addition to the street-level research"—plus: "The research will be conducted during daylight hours in parts of the Bronx, Brooklyn, Queens, Staten Island and in Manhattan primarily from 59th Street to the Battery... The field study is designed to have zero impact on commuting and other public activity. Members of the public may notice clearly marked boxes containing the air sampling equipment secured in subway stations, on street light poles, and hand-carried by researchers."

The study is being funded by a $3.4 million Department of Homeland Security Transit Security Grant. It's too bad they don't give out grants for figuring out how to mask eau de garbage in sweltering stations.