Subway stop in Manhattan (Spencer Platt/Getty Images)

New York City commuters could face delays this week as federal authorities test the vulnerability of New York City's subway system to a possible chemical attack.

Beginning at 11 a.m. Monday the Department of Homeland Security will be releasing low concentrations of a harmless, non-toxic gas into several midtown Manhattan subway stations.

Officials say data from the five-day drill will help first responders better understand how airborne contaminants travel through the subway system.

There is no health risk to the public.

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