The NYPD waging an anti terror action in subway systems.
The NYPD and Long Island's Brookhaven National Laboratory will begin installing air sampling equipment to study how chemical weapons could be dispersed through the city's subway system.
The three-day study, called "Subway-Surface Air Flow Exchange" will be conducted in parts of all five boroughs beginning Tuesday morning.
Researchers will disperse low level concentrations of harmless gases at several subway and street-level locations in Manhattan for 30 minutes each morning.
Data from the study will help first responders better understand how airborne contaminants could travel through the system so appropriate emergency responses can be developed.