Scientific study shows high pollution levels in NYC subway, Black and Brown commuters and workers impacted the most

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PLOS One, a science and medical journal, published a new study last week showing increasing concentrations of air pollution on platforms and in train cars throughout the New York City subway system, which impacts all commuters, but have a disproportionate effect on low-income Black and Hispanic New Yorkers, who already have longer-than-average commute times.

The study sampled 3.1 million working commuters across Manhattan, Brooklyn, Queens, and the Bronx, analyzing their trips through a racial justice lens. It also examined general home-to-work mobility patterns and possible exposure levels to the subway’s high concentrations of fine particulate matter (PM2.5) pollution. 

According to the U.S. Environmental Protection Agency (EPA), particulate matter is the mixture of solid particles, like dust, dirt, soot, or smoke and liquid droplets found in the air. These particles can also be found at construction sites, unpaved roads, fields, smokestacks or fires, power plants, and from cars. The EPA confirms that particulate matter can get deep into your lungs and even the bloodstream in some cases. This may cause serious health problems, such as cardiovascular, respiratory, metabolic, and neurological disorders. 

PM2.5 poses the greatest risk to health, said EPA. Despite trains being widely recognized as a safer and more environmentally friendly way to travel as opposed to gas-powered cars and buses, the city’s subway system still contributes to high PM2.5 levels for New Yorkers. 

This comes from metal-rich particles mostly generated by the wear and friction of brakes and between rails and wheels, said the study. The subway’s train frequency, station depth, ventilation, age of the station, and piston effect are also contributing factors. 

The longer people are exposed to the PM2.5 levels, the higher the possibility of negative health outcomes. The PLOS One study analyzed economically disadvantaged communities and racial minority groups living farther from the city center of Manhattan, and confirmed that on average they take more frequent and longer subway trips and are disproportionately exposed to air pollution in the subway. 

“The disparity here is less about the pollution on one line or one platform compared to another, but rather it is mostly about the duration of exposure, because most people in lower-income communities live further away so they are having longer commutes and therefore higher exposure,” said Masoud Ghandehari, New York University’s Tandon School of Engineering professor, and chief researcher on the study, in a Newsweek interview. 

Ghandehari added that stations and platforms don’t have air purification systems and are, therefore, more polluted than the actual subway cars.

Mayor Eric Adams, at an in-person conference on Aug. 13, said that he was unfamiliar with the subway study. He did, however, acknowledge the long-standing issue of air pollution in the city’s subway system based on his own experiences. Adams served as a NYPD transit police officer from 1984 to 2006 and recalled certain practices he and his colleagues had to perform to minimize health risks.

“When I was a transit cop, there was a well-known ritual we would do at the end of the tour. You take water drops, put it in your nostrils, and you have to blow out all the steel dust,” said Adams at the conference. “And it was very [real], everyone knew that. That is how you clear the steel dust out of your nostrils, and people don’t realize that it exists.”

Danny Pearlstein, Riders Alliance policy and communications director, confirmed that the “steel dust” and particulate matter in the city’s subways have been an issue since the system was built over a century ago. In some subway systems overseas, trains use rubber wheels, but Pearlstein said there are still emissions of a sort in those instances. 

He highlighted the often overlooked issue that high PM2.5 levels impact transit workers of color, who are more likely to spend more time than the average commuter in the subway and outside of more ventilated train cars. He hypothesized that the constant exposure may have contributed to MTA workers dying from COVID during the pandemic.

“There’s a lot of study and discussion about why so many transit workers died right at the beginning of the pandemic. They were exposed in close quarters, exposed to one another [and] the MTA initially didn’t allow them to wear masks because it wasn’t a part of their uniform,” Pearlstein said. “And a possibility is that their respiratory systems were already compromised because of unsafe particulate matter in the workplace.”

The city’s Metropolitan Transportation Authority (MTA) workforce is about 47% Black and 19% Hispanic workers, according to city reports from 2022. 

“This is an important issue that people need to take a look at and related to that it may require some investment,” Pearlstein said. “There’s tens of thousands transit workers and millions of transit riders in the subway who should be taken care of, especially because disadvantaged communities are the most vulnerable populations here.”

Aaron Donovan, MTA deputy communications director, declined to give an official statement in response to an AmNews inquiry. 

He pointed out that the study’s “disclaimer” about high PM2.5 levels notes that the EPA health outcomes guidelines are largely based on particulate matter from fossil fuel combustion and the inhalation of iron-based particles– as opposed to trains and metal particles. He noted that 41% of the subway system is outdoors and that 100% of subway cars contain MERV8 or MERV9 filters since the COVID-19 pandemic in 2020.

“I just want to say, overall, transit is how we reduce emissions in the city in general, right? So, the more people we take out of cars, put on buses, and in the subway, the more we improve the climate for all New York City residents. I don’t want to lose sight of that,” said Meera Joshi, New York City deputy mayor for operations, about the study.
“But I know the MTA, and we’re happy to follow up with them, [were] very rigorous about air quality, which started during COVID, and they have retained some of that testing. But I am sure that that muscle that they exerted extremely well during COVID, since that was one of our only safe ways to travel, is still in place.”