Commuters of subway stations who wait at stations near tunnels that flow beneath the city's rivers are exposed to greater amounts of dangerous air pollutants than those who wait at other stations.
Experts identified it as the 'river-tunnel effect,' which may help explain the nation's largest subterranean transportation system's extraordinarily poor air quality and has specific consequences for stations near rivers in general.
Hazardous Air Pollutants up to 130% in Subway Near River Tunnels
Researchers at NYU Langone Health said that taking a breath of air on a riverfront in New York City subway might be as harmful as inhaling smoke from a forest fire.
Their study, titled "Investigation of a river-tunnel effect on PM2.5 concentrations in New York City subway stations" published in Transportation Research Part D: Transport and Environment, revealed that hazardous air pollutants were up to 130% greater in subway stations near river tunnels than in other stations.
The amount is equivalent to those detected in smoke flowing from forest fires and building demolitions, Patch reported. David Luglio, the primary author of the study, said that the cause for high air pollutant levels appears to be due to the geography of New York as few other megacities have such huge rivers.
He said that poor ventilation in stations near the body of water appears to result in a "river-tunnel effect," which traps air pollutants. This kind of phenomenon has not been seen in any other study around the world but some of these concentrations are quite high than in other environments.
Metropolitan Transit Authority (MTA) Michael Cortez critiqued the findings, saying that the researchers only took samples at the most active time of the day, which might not be as accurate to EPA standards for daily exposure limits. He said that they conducted air quality testing in the subway before and found no health risks, but said that they will review the study to ensure the safety of customers and employees.
Nonetheless, the findings coincide with a modest but increasing return to subways by commuters who had mostly avoided them during the coronavirus outbreak.
New Findings Help Improve Conditions in Subway Stations Near Rivers
To compare and validate the river-tunnel interaction, the researchers examined particle accumulation on the B-line, a railway route that crosses the East River by bridge rather than a tunnel, according to Science Daily. Notably, pollutant levels were lower in the two stations closest to the river on this railway route than in stations further away, which is the expected reversal of the river-tunnel effect.
Research senior author Terry Gordon, Ph.D., an assistant professor of medicine at NYU Langone Health, said that the findings give them a clearer understanding of where to improve the conditions of New York City's subterranean subway stations. Increasing airflow and washing tunnel walls and falling will remove recycling trash to make stations safer for riders and transportation employees.
As a member of NYU Langone's Center for the Investigation of Environmental Hazards, Gordon warns that it's unknown whether the river-tunnel impact exists in other places because the study only looked at subways in New York City.
He goes on to say that the research team's next step will be to look at the effects of subway pollutants on human cells in order to better determine the degree of exposure required to represent a risk to human health.
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