In addition to easing traffic, New York City’s new congestion pricing plan is expected to produce environmental benefits, including fewer greenhouse gas emissions and cleaner air.
But if motorists avoid the tolls leading into Manhattan via detours, other areas in the metropolitan region could see their air quality deteriorate.
The South Bronx, already burdened by a large number of pollution-spewing trucks that contribute to elevated rates of asthma, is of particular concern. And some preliminary data from the first two weeks of congestion pricing, which began on Jan. 5, find a possible uptick in traffic there.
Local activists, like Mychal Johnson, are paying attention. “You want to reduce congestion, please do it here, do it where we’re breathing toxic air,” said Mr. Johnson, co-founder of South Bronx Unite, a nonprofit focused on social, economic and environmental issues.
It’s still too early to draw any conclusions about traffic in the South Bronx and its link to congestion pricing. But early data from Inrix, a transportation analytics firm, showed that afternoon travel times on major highways and expressways in the Bronx had increased by 9 percent during the first two weeks after tolling started, compared with the same time period in 2024. There was also a 2 percent decrease in travel times in the mornings.
Travel times can serve as a measure of congestion, with trips that take longer indicating more traffic, but they can also reflect other impediments, such as accidents or construction projects. INRIX collected the data from devices like cellphones and GPS navigation systems.
“We simply cannot bear even one more truck,” Mr. Johnson said.
An environmental assessment of congestion pricing, published by the Metropolitan Transportation Authority before the program took effect, said that traffic could become heavier in parts of the South Bronx following the implementation of the tolls.
The M.T.A., the state agency that operates congestion pricing, referred to previous statements from its chief executive, Janno Lieber, when approached for comment.
“We’re making the big investments that more than offset any hypothetical impact from truck traffic in the Bronx that’s a result of congestion pricing,” said Mr. Lieber on “The Brian Lehrer Show” last month.
Other areas in the region were also vulnerable to possible traffic increases, including portions of Staten Island. The State of New Jersey argued in a lawsuit in federal court that the environmental effects of the plan on the state had not been sufficiently studied. The judge in the case declined to halt congestion pricing, but he did ask for further details from federal transportation officials about aspects of the tolling program that would mitigate any negative outcomes for New Jersey communities.
Several scientists and researchers cautioned that gauging the exact effect of congestion pricing on air quality would take time, as well as careful analysis of complex factors.
“From a scientific viewpoint, we need at least one year of data,” said Holger Eisl, an environmental science professor at Queens College who partners with the city’s Department of Health and Mental Hygiene to examine air quality. Because of variables in atmospheric conditions, he explained, “you want to see the data pattern from season to season.”
Congestion pricing charges most drivers $9 to enter the core of Manhattan, which has some of the most traffic-choked streets in the world. The program aims to provide funds for mass transit and get cars off the road.
Should the tolling program continue uninterrupted — the Trump administration is threatening to halt it — the health department plans to share its environmental findings with the M.T.A. in early 2026, said Sarah Johnson, the executive director of the city’s Air Quality Program.
Dr. Eisl said that even when comparing full years of data, every year has unique elements that need to be accounted for since weather patterns affect air quality. “For example, the biggest item that cleans the atmosphere is rain,” he said.
Also, in New York City, traffic accounts for just 14 percent of air pollution caused by fine particulate matter: tiny, toxic particles produced by burning fossil fuels. Because of the city’s density, buildings and other sectors generate more of this kind of air pollution, according to the health department.
Meteorological elements like wind speed and turbulence, in addition to general trends in air pollution, must be considered when examining air quality fluctuations, said Markus Hilpert, an associate professor of environmental health sciences at Columbia University. That is why it’s important to run models based on plentiful data, he said.
Dr. Hilpert intends to do this in partnership with South Bronx Unite, which is adding 25 air monitors to its network of 40 throughout the neighborhood. The professor and other researchers will analyze the data from the sensors and release their findings later this year.
With dense housing that sits next to major roadways like the Cross Bronx Expressway, the South Bronx is also home to multiple waste transfer stations and warehouses that contribute to poor air quality. Hunts Point, one of the largest food distribution centers in the country, has 13,000 trucks coming and going daily.
Large diesel trucks are more toxic than smaller, gas-fueled cars, spewing 10 times as much PM2.5, the deadliest form of particulate matter, into the atmosphere, according to data from the Bureau of Transportation Statistics, a federal agency. These particles are a trigger for asthma, a longtime health challenge in the South Bronx.
To offset any environmental harm from congestion pricing, the M.T.A. has allocated just over $71 million for mitigation efforts in the neighborhood, including a new asthma center, air filtration systems in schools, park renovations, replacing up to 1,000 refrigerated trucks with cleaner vehicles and expanding charging networks for electric trucks. All of the projects are in the planning or development stages.
But for the activists involved with South Bronx Unite, those actions fall short.
“If they know that problem is already pre-existing here, mitigation after the fact is not helpful,” Mr. Johnson said. “We need real, solid solutions.”
