Commuters and transit workers in underground subway systems are exposed to relatively poor air quality that may put them at greater risk for cardiopulmonary disease and adverse respiratory outcomes if exposure levels exceed environmental and occupational guidelines. Researchers evaluated the air quality in three subway and rail systems in the New York metropolitan area and then compared their findings with those of three other subway systems in other northeastern cities.
Real-time and gravimetric measurements of particulate matter with aerodynamic diameter < 2.5 [mu]m (PM2.5) were made during rush-hour periods on trains and at under- and aboveground platforms. The measurements revealed variable and, in places, very high PM2.5 exposures of commuters and transit workers. PM2.5 concentrations on subway trains and underground platforms were much higher than on aboveground platforms, at least during rush hours.
In the subway systems studied, the findings suggest, commuters are exposed to poor air quality during time spent in underground subway stations. These exposures may be high enough in some stations to increase the risk of adverse health effects. PM2.5 levels measured during rush hours were, with only one exception, two to seven times higher than the U.S. Environmental Protection Agency's 24-hour ambient air standard. Mitigation efforts, such as improved ventilation, are warranted to protect the health of commuters and transit workers, the authors conclude.