Pre-COVID subway air polluted from DC to Boston, but New York region's is the worst

February 10, 2021

Commuters now have yet another reason to avoid packing themselves into subway stations. New York City's transit system exposes riders to more inhaled pollutants than any other metropolitan subway system in the Northeastern United States, a new study finds. Yet even its "cleaner" neighbors struggle with enough toxins to give health-conscious travelers pause.

Led by NYU Grossman School of Medicine researchers, the study measured air quality samples in 71 stations at morning and evening rush hours in Boston, New York City, Philadelphia, and Washington, D.C. Among the 13 underground stations tested in New York, the investigators found concentrations of hazardous metals and organic particles that ranged anywhere from two to seven times that of outdoor air samples.

Notably in the report, publishing online Feb. 10 in the journal Environmental Health Perspectives, one underground platform on the PATH line connecting New Jersey and Manhattan (Christopher Street Station) reached up to 77 times the typical concentration of potentially dangerous particles in outdoor, aboveground city air. This figure is comparable to sooty contamination from forest fires and building demolition, the study authors say.

Air quality was also measured in another 58 stations during rush hours in Boston, Philadelphia, and Washington. While no station's readings reached the severe levels of contamination seen in New York's worst transit lines, underground subway stations within each of these cities still showed at least twice the airborne particle concentrations as their respective outside samples at morning and evening rush hours.

"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.

"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.

Further analysis of air samples showed that iron and organic carbon, a chemical produced by the incomplete breakdown of fossil fuels or from decaying plants and animals, composed three-quarters of the pollutants found in the underground air samples for all measured subway stations. Although iron is largely nontoxic, some forms of organic carbon have been linked to increased risk of asthma, lung cancer, and heart disease, the study authors say. Gordon notes that further research is needed to assess potentially higher risk for transit workers who spend far longer periods of time in the stations than riders.

The Metropolitan Transit Authority reported that 5.5 million people rode New York City's subways every day in 2019, while PATH puts its daily ridership at more than 284,000.

For the investigation, the research team took over 300 air samples during rush hour in stations in Manhattan, Philadelphia, Washington, Boston, and along train lines connecting New York City to New Jersey and Long Island. The data reflects more than 50 total hours of sampling across about 70 subway stops. In addition to real-time monitoring of the air quality, the team also used filters to collect airborne particles for later analysis.

According to the findings, the PATH-New York/New Jersey system had the highest airborne particle concentration at 392 micrograms per cubic meter, followed by the MTA-New York at 251 micrograms per cubic meter. Washington had the next highest levels at 145 micrograms per cubic meter, followed by Boston at 140 micrograms per cubic meter. Philadelphia was comparatively the cleanest system at 39 micrograms per cubic meter. By comparison, aboveground air concentrations for all measured cities averaged just 16 micrograms per cubic meter.

Meanwhile, the Environmental Protection Agency advises that daily exposures at fine particle concentrations exceeding 35 micrograms per cubic meter pose serious health hazards.

Besides the Christopher Street PATH station, the most polluted stations in the Northeast included Capitol South in Washington, Broadway in Boston, 2nd Avenue on the F line New York City, and 30th Street in Philadelphia, according to the findings.

Gordon cautions that the researchers did not measure riders' short-term exposure to the airborne substances, which would more closely mimic their experiences dashing to catch a train at the last minute. In addition, it remains unclear whether the steep drop in New York subway ridership due to the COVID-19 pandemic has influenced the metro's air quality, he adds.

Next, Gordon says he plans to investigate sources of subway station air contamination, such as exhaust given off by diesel maintenance locomotives, whipped up dust from the remains of dead rodents, and poor ventilation as potential culprits. He also encourages researchers and transit authorities to examine why some systems are less polluted than others in a bid to adopt practices that might relatively quickly make stations safer for riders.
-end-
Funding for the study was provided by National Institute of Environmental Health Sciences grants P30 ES000260, P30 ES009089, and T32 ES007324.

In addition to Gordon and Luglio, other NYU Grossman researchers include Maria Katsigeorgis; Jade Hess; Rebecca Kim; John Adragna, George Thurston, Colin Gordon, and Amna Raja. Jonathan Fine, MD, at Norwalk Hospital in Norwalk, Conn., was also involved in the study. M.J. Ruzmyn Vilcassim, PhD, at the University of Alabama in Birmingham served as the study co-senior author.

Media Inquiries
Shira Polan
212-404-4279
shira.polan@nyulangone.org

NYU Langone Health / NYU School of Medicine

Related Air Quality Articles from Brightsurf:

COVID-19: Air quality influences the pandemic
An interdisciplinary team from the University of Geneva and the ETH Z├╝rich spin-off Meteodat investigated possible interactions between acutely elevated levels of fine particulate matter and the virulence of the coronavirus disease.

COVID-19 shutdown effect on air quality mixed
In April 2020, as remote work and social distancing policies were in place in Delaware and a number of other states, there was a sense the skies were clearer and less polluted with fewer people on the road.

School absences correlate to impaired air quality
In Salt Lake City schools, absences rise when the air quality worsens, and it's not just in times of high pollution or ''red'' air quality days--even days following lower levels of pollutions saw increased absences.

Unexpected wildfire emission impacts air quality worldwide
During wildfires, nitrous acid plays a leading role--spiking to levels significantly higher than scientists expected, driving increased ozone pollution and harming air quality, according to a new study led by the University of Colorado Boulder and the Belgian Institute for Space Aeronomy.

Evergreen needles act as air quality monitors
Every tree, even an evergreen, can be an air quality monitor.

Research brief: New insight on the impacts of Earth's biosphere on air quality
A new study provides the first global satellite measurements of one of the most important chemicals affecting Earth's atmosphere.

Extending the coverage of PM2.5 monitoring to help improve air quality
A team of researchers in China has improved the method to obtain mass concentrations of particulate matter from widely measured humidity and visibility data.

Air quality impacts early brain development
Does living close to roadways pose a risk to the developing brain?

COVID-19 lockdowns significantly impacting global air quality
Levels of two major air pollutants have been drastically reduced since lockdowns began in response to the COVID-19 pandemic, but a secondary pollutant -- ground-level ozone -- has increased in China, according to new research.

Can poor air quality make you gain weight?
A new study links air pollution to changes in the human gut microbiome which could fuel diabetes, obesity and inflammatory bowel diseases like colitis and Crohn's disease.

Read More: Air Quality News and Air Quality Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.