DHS scientists to continue studying airflow in MBTA subway system

Commuters in Boston's MBTA subway system will notice scientific equipment and researchers with electronic monitoring devices throughout the system August 20 -27, while the U.S. Department of Homeland Security (DHS) continues a scientific study of airflow throughout the underground portion of the subway system. The first portion of the study was conducted in December.

Led by DHS’s Science and
Technology Directorate, the purpose of the study is to gather data on the
behavior of airborne contaminants if they were to be released into the subway-part
of the Department’s ongoing commitment to preparedness and the shared
responsibility of protecting the nation’s critical infrastructure.

"The movement of airborne
contaminants can be affected by differences in temperature and humidity, so a
comprehensive study requires gathering data in both winter and summer months,"
said program manager Teresa Lustig. "In addition to comparing the effects of
seasonal conditions, a second phase of the study also allows us to test the
effectiveness of some of the proposed countermeasure and response strategies
derived from analysis of the December tests."

"Our customers and
employees should know that the MBTA is working closely with our federal
partners in order to make the transit system as safe as possible," MBTA Transit
Police Chief Paul MacMillan added.

In order to collect data on
the behavior of airborne contaminants, the study involves releasing non-toxic,
inert, odorless gas and particle tracers into the subway system. Particle and
gas concentrations will be sampled in more than 20 stations and in subway cars
covering the entirety of the underground portion of the MBTA subway system.
While the deliberate release of chemical or biological agents is of primary
concern, the study will also help researchers understand airflow
characteristics for smoke or unintentional spills of chemicals or fuels-providing
a direct benefit to MBTA for use in developing evacuation, ventilation and
other incident response strategies. The information will also help guide the design
of next generation chemical and biological agent detection systems.

Although the equipment will
be visible, the study will not disrupt normal activities or present any
inconvenience to the public. Commuters may notice a variety of electronic
equipment positioned in stations or being hand-carried by researchers.

The study will be conducted
by researchers from Argonne National Laboratory, Lawrence Berkeley National
Laboratory and an international team from ICx Technologies of Arlington, Va.,
Defence Science and Technology Laboratory of the United Kingdom and Chemistry
Centre of Australia.

The tests will use sulfur
hexafluoride and perfluorocarbon gas tracers, both innocuous, non-toxic, inert
gases that have been used in dispersion experiments since the 1960s. Sulfur
hexafluoride is a harmless, common tracer gas used for indoor and outdoor air
testing. Perfluorocarbons are used in eye surgery and other medical
applications. An inert particle tracer will also be used. These tracers are
tagged with sodium fluorescein and a common optical brightener. Sodium
fluorescein is a biologically inert, non-toxic organic dye used in oceanography
as a marker in seawater, and in medical imaging applications. The optical
brightener is used in many laundry detergents and in paper manufacturing.