U.S. subway systems filled with hazardous air pollutants, but New York City ranks worst of all

NEW YORK — The New York City subway has never been synonymous with cleanliness. Still, the findings by researchers at New York University may cause many locals to reassess their daily commute. Their study finds the Big Apple’s aging subway system exposes riders to more air pollution and inhaled pollutants than any other metropolitan subway on the east coast of the United States.

Residents of Philadelphia, Boston, or Washington, DC aren’t necessarily breathing in clean air while riding the rails. Study authors say all of these cities’ transit systems leave much to be desired in terms of clean air as well.

Prior to the onset of the COVID-19 pandemic, the research team measured air quality in 71 different transit stations during morning and evening rush hours across those four major cities. The 13 stations tested in NYC stood out to researchers, due to the extremely high levels of hazardous metals and organic particles discovered. Concentrations of harmful pollutants recorded at these stations ranged anywhere from two to seven times greater than outdoor air readings.

The most hazardous subway stations in the country?

One NYC station in particular was especially smog-ridden. The Christopher Street PATH train station connecting New Jersey and Manhattan showed air pollution levels reaching 77 times greater than normal outdoor air. For an idea of just how bad that is, researchers say the air at this station was similar to air near a forest fire or recent building demolition.

Regarding the other cities’ stations, none reached levels anywhere near New York’s worst offenders. However, all of the stations examined in Boston, Philly, and Washington showed at least twice the airborne particle concentrations recorded outside.

“Our findings add to evidence that subways expose millions of commuters and transit employees to air pollutants at levels known to pose serious health risks over time,” says study lead author David Luglio, a doctoral student at NYU Grossman, in a university release.

“As riders of one of the busiest, and apparently dirtiest, metro systems in the country, New Yorkers in particular should be concerned about the toxins they are inhaling as they wait for trains to arrive,” adds co-senior study author Terry Gordon, PhD, a professor in the Department of Environmental Medicine at NYU Grossman.

What’s making subways across America so polluted?

So, the east coast’s subway systems have an air pollution problem. That much is clear. So where is all the smog coming from? According to the air samples, iron and organic carbon constitute roughly 75 percent of all the pollutants recorded in these stations. Organic carbon is a chemical that usually appears due to the incomplete breakdown of fossil fuels or from decaying plants and animals. While iron is generally non-toxic, researchers say organic carbon has a connection to a variety of health problems like lung cancer and heart disease.

Statistically, the PATH-New York/New Jersey system showed the highest pollution levels reading 392 micrograms per cubic meter. After that, the MTA-New York City system came in at number two with 251 micrograms per cubic meter. Washington, DC (145 micrograms) and Boston (140 micrograms) follow the Big Apple as the next most polluted subways.

Philadelphia had the cleanest air of the group with just 39 micrograms per cubic meter. For reference, outdoor air readings across all four cities average 16 micrograms per cubic meter. According to the Environmental Protection Agency, daily exposure to more than 35 micrograms per cubic meter is a health hazard.

No matter which big city you visit, study authors discovered stations which stand out from the rest when it comes to pollution. Capitol South in Washington, Broadway in Boston, 30th Street in Philadelphia, and 2nd Avenue on New York’s F-line rank among the worst stations in the study.

In conclusion, study authors say new research is warranted to examine what impact the COVID-19 pandemic and much lower daily commuting rates have had on these pollution levels.

The study is published in Environmental Health Perspectives.