Airflow Study In New York City Streets and Subways This Summer

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Posted on April 25, 2013

The New York City Police Department and the U.S. Department of Energy’s Brookhaven National Laboratory are scheduled to conduct this July the largest urban airflow study ever to better understand the risks posed by airborne contaminants, including chemical, biological and radiological (CBR) weapons as they are dispersed in the atmosphere and in the City’s subway system. The NYPD will use the data collected during the three days of research to optimize emergency response following an intentional or accidental release of hazardous materials.

“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,” said Police Commissioner Raymond W. Kelly, adding that, “This field study with Brookhaven’s outstanding expertise will help prepare and safeguard the city’s population in the event of an actual attack.”

“Brookhaven Lab is a world leader in the use of tracer gases to study airflow, and we are excited about this opportunity to apply that expertise to enhancing the safety of New York City residents and emergency responders,” said Brookhaven Lab Director Doon Gibbs.

Both agencies will be working with the Metropolitan Transportation Authority to test airflow through the subway system.

“The NYPD, in partnership with the MTA, is responsible for keeping more than 5 million daily subway customers safe and secure. This study will bolster the NYPD’s understanding of contaminant dispersion within the subway system as well as between the subway system and the street, thereby improving its ability to better protect both our customers and the city population at large,” said MTA Acting Chairman Fernando Ferrer. “We are glad they are joining Brookhaven National Laboratory for such an important effort, which will benefit the New York City subway without affecting its regular operations.”

The Subway-Surface Air Flow Exchange (S-SAFE), as the project is formally known, was commissioned by the NYPD and funded through a $3.4 million Department of Homeland Security Transit Security Grant. It is the first of its scale to study airflow in a dense, complex urban environment both below and above-ground. Researchers from Argonne National Laboratory and Los Alamos National Laboratory, along with additional meteorologists and engineers, will support Brookhaven’s scientists as they track the movement of harmless tracer gases detected by air sampling devices placed in select locations on the street and in the subway system.

There will be approximately 200 sampling devices deployed during this study. During the study, researchers will disperse low concentrations of harmless gases known as perfluorocarbons at select subway and street-level locations over three, non-consecutive days in July. Weather conditions will determine which days are selected for the tests, and will be announced to the public a day in advance. The research will be conducted during daylight hours in parts of the Bronx, Brooklyn, Queens, Staten Island and in Manhattan from 59th Street to the Battery.

Perfluorocarbon tracer gases (PFTs) present no health or environmental hazard. They are non-toxic, inert, odorless, and invisible, and have been used in airflow studies since the 1980s, including a 2005 Urban Dispersion Program (UDP) conducted in Manhattan. PFTs also are used in medical applications including eye surgeries and artificial breathing systems.

The NYPD and MTA worked closely together on planning and implementation of the study, which will include 21 subway lines and several dozen stations citywide, in addition to the street-level research. 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.

In addition to the study in Manhattan in 2005, previous airflow studies were conducted in subway systems in Boston, and Washington, D.C. – but none as extensive as the one planned for New York City in July.

While the study is focused on the airflow and dispersion of airborne contaminants resulting from the release of a CBR agent, the findings will also enable City agencies to better understand dispersion characteristics of other potential inhalational hazards, such as smoke or fumes from chemical spills. The study is also expected to help police and other agencies decide where to best locate CBR detection equipment. Results from the study will help authorities refine evacuation or other responses in the event of an emergency.

Source: BNL