People traveling on subway systems in major U.S. cities are exposed to unsafe amounts of air pollution, with commuters in New York and New Jersey experiencing the highest levels of pollution.
Small particles in the air, probably thrown by train brakes or friction between train wheels and tracks, are abundant in the 71 underground stations conducted by researchers during the morning and evening rush hours in Boston, New York, Philadelphia and Washington DC, the cities containing the largest part of the metro systems in the US.
The levels of these small pollution spots, called PM2.5, were much higher than the national, safe daily levels of 35 micrograms per cubic meter in each of the cities. New York’s Metropolitan Transit Authority (MTA) system has 251 micrograms per cubic meter, followed by Washington DC at 145 micrograms per cubic meter. Philadelphia was, relatively speaking, the cleanest system, but still exceeded the limit within which serious health hazards are threatened.
“New Yorkers should be especially concerned about the toxins they inhale,” co-author of the study, Terry Gordon, a professor at New York University’s Grossman School of Medicine, said in the study that concentrations of hazardous metals and organic particles were everywhere. from two to seven times higher than outdoor monsters in the city.
Christopher Street, a Manhattan station that helps connect New York and New Jersey, had an incredible pollution level of 1499 micrograms per cubic meter, about 77 times higher than the above-ground pollution. This is a level of pollution that is more common during a major wildfire or during a demolition of the building, the researchers said.
“It was the worst pollution ever measured in a subway station, higher than some of the worst days in Beijing or Delhi,” Gordon said. He was so amazed at the reading on his instruments that he had to ask colleagues to perform repeated tests. to ensure that the figures are correct. “It just wasn’t credible. My colleague is there and his airways feel tight after an hour or so. ‘
The researchers calculated that someone with a typical commute to and from Christopher Street increased their risk of an adverse cardiovascular event by 10%. However, the station was not the only one with elevated toxins in the air, with Broadway in Boston, Second Avenue in New York City and 30th Street in Philadelphia being the most polluted stops in the Northeastern United States. “People have to worry a lot about these high levels,” Gordon said.
The subway systems typically transport millions of people through U.S. cities, with MTA, New York’s largest country, transporting 5.5 million people to New York every day in 2019. However, the use of metros fell sharply during the coronavirus pandemic, with many of the remaining commuters working in the front line doing essential work.
Analysis of the air samples shows that the pollution consists mainly of iron and organic carbon, a chemical produced by the decomposition of fossil fuels or decaying plants and animals. The latter, when inhaled, has been linked to an increased risk of respiratory conditions, lung cancer and heart disease. It is not entirely clear why pollution in metros is worse than above ground, although the air is able to dilute and remove some of the fumes from cars and trucks, while underground stations are often poorly ventilated.
Gordon stressed that more research is needed to determine the exact impact on commuters and transport workers who spend a long time in the polluted stations. The researchers also plan to further investigate the exact sources of the pollution, which could range from the exhaust gases given by diesel locomotives to dust stored from the remains of dead rodents.
“This is an important contribution, especially to our understanding of the excessive burden of air pollution faced by low-income and color communities,” said Gretchen Goldman, research director of the Union of Concerned Scientists, who was not involved in the study. , published in Environmental Health Perspectives.
‘As the scientific community works to better understand the exposure and potential consequences for the health of air pollution in the urban environment, I hope local decision-makers use this valuable work to inform the best ways to address the well-known racial and socio-economic address inequalities in exposure to US air pollution. cities. ”