Congestion Pricing Could Bring Cleaner Air. But Maybe Not for Everyone.

When congestion pricing takes effect in New York City later this month, officials say it will create an array of benefits: The system’s tolls will generate revenue for improving mass transit while prompting some drivers to avoid Manhattan, potentially reducing traffic and air pollution, as well as carbon emissions that contribute to climate change.

Some of those goals are already within sight: Devices that will monitor cars and send bills to drivers are in place, and the Metropolitan Transportation Authority, which will operate the system, has begun to detail the transit repairs and upgrades it plans to spend its windfall on.

For now, though, it is unclear how much the program will contribute to New York State’s ambitious goal of reducing greenhouse emissions 85 percent by 2050. And some people worry that less air pollution in some areas will be offset by more in others, despite efforts to keep that from happening.

According to an environmental assessment by the authority, congestion pricing could decrease air pollution overall in three boroughs: Manhattan, Brooklyn and Queens. The concern is that rerouted traffic could increase it in the Bronx and on Staten Island.

“It’s safe to say the direct air-quality benefits would be modest but measurable overall,” said Eric A. Goldstein, a senior attorney and New York City environment director at the Natural Resources Defense Council. The plan, he added, is worthwhile because of its benefits for public transit, whose health is crucial for luring people away from private vehicles.

“If you look at London and Stockholm, they had improved traffic, modest air quality and jolts of adrenaline to their transportation systems,” he said, referring to similar programs in those cities.

To counter a potential air pollution increase in the South Bronx and other parts of the region, government officials have committed $155 million to initiatives like an asthma center, improved ventilation in schools by highways and renovating parks and other green spaces.

But such measures are inadequate for the South Bronx, which has grappled with air pollution’s effects for years, said Arif Ullah, the executive director of South Bronx Unite, a nonprofit that focuses on social, economic and environmental issues.

Mr. Ullah said his group supported congestion pricing in principle but opposed the current plan. The South Bronx, one of the areas that is projected to have more air pollution because of drivers avoiding the toll zone, already has high levels of congestion and toxins in the air, and high asthma rates.

“If we are getting more public transit with poorer air, it seems like a deal with the devil,” said Assemblyman Kenny Burgos, a Democrat who represents a section of the southeast Bronx and opposes the current plan.

Mr. Burgos expressed concern about a possible increase in delivery trucks, which are among the worst polluters. He also mentioned the possibility that a major distribution center in the Manhattan congestion zone, like one operated by United Parcel Service on West 43rd Street, would route more deliveries through the Bronx to avoid tolls. A UPS spokesman said the company was considering the idea but had not made plans.

Pollution in the South Bronx should be addressed separately and aggressively, not used as a bargaining chip to push the program through or as an argument to shut it down, said Jacqueline Klopp, the director of Columbia University’s Center for Sustainable Development and a congestion pricing supporter.

Concerns about the plan extend to New Jersey, where opponents have sued to block it from taking effect, complaining that environmental studies of its potential impact have not been adequate. Similar suits have been filed in New York courts. The system’s start, which is scheduled for June 30, could be postponed based on the outcome of the lawsuits.

Under congestion pricing, most vehicles will be charged $15 to enter the area of Manhattan below 60th Street during the peak hours of 5 a.m. to 9 p.m. Trucks would pay $24 or $36 at peak hours, depending on their size.

The program is expected to generate $1 billion in annual revenue, which the authority plans to use to secure $15 billion in financing it needs for infrastructure work on the city’s 119-year-old transit system.

Because climate change is putting even greater demands on that system, officials say, another $6 billion is needed for projects like elevating equipment, updating vents and building berms and flood walls to prepare for the effects of extreme weather.

Congestion pricing is predicted to reduce traffic in Manhattan’s core about 17 percent, or about 120,000 vehicles a day, according to the mayor’s office. The M.T.A. has offered one potential scenario under which particulate matter — inhalable particles produced by burning fossil fuels, among other sources — would decrease about 11 percent in the district.

The last time congestion and air pollution dropped significantly in New York was during the pandemic, when many drivers stopped coming into the city. Predictions about the effect congestion pricing will have pale in comparison to what happened when the city locked down, said Bob Pishue, an analyst with the global traffic and data analytics company Inrix. In 2021, traffic entering Manhattan below 14th Street was down 55 percent, he said.

In Stockholm, air pollution has declined since congestion pricing was introduced 18 years ago, said Jonas Eliasson, a director at the Swedish Transport Administration. He added that the improved air quality in Sweden’s capital was also attributable to increasingly strict regulations for new trucks and cars and the growing presence of electric vehicles.

In London, congestion pricing has evolved since its introduction more than 20 years ago. Zone boundaries have expanded, fees have increased and regulations have tightened. Traffic, though reduced, continues to be a challenge, because of more people living there and more street space has gone to bicycle lanes and other alternative travel routes, said Kate Slevin, executive vice president of the Regional Plan Association, an urban planning nonprofit in New York.

London’s air quality has improved because of several initiatives, including congestion pricing and an “ultra low emission zone” program that charges fees to polluting vehicles that enter a designated area in London.

Last year, average particulate matter concentrations across London did not exceed the World Health Organization’s interim guidelines for the first time, and nitrogen dioxide, a gas produced by burning fuel, was cut nearly in half from 2016 to 2023.

London is similar to New York City in that most greenhouse gas emissions there come from buildings. That could help explain why congestion pricing and other car-related regulations in London have helped to improve air quality, while meeting carbon emissions goals remains difficult.

Buildings, which are responsible for 70 percent of New York City’s greenhouse gas emissions, also contribute to air pollution, said Talor Gruenwald, a data scientist at Rewiring America, a nonprofit that promotes electrification. That means reducing carbon emissions from buildings in dense cities may be a more powerful way to both improve air quality and to lower greenhouse gas emissions overall.

“Buildings and cars both emit fine particulate matter and nitrogen dioxide in similar quantities,” Mr. Gruenwald said. Although the worst offenders are oil-powered buildings, buildings powered by natural gas also pollute the air, he added.

In 2017, buildings in New York produced 1,058 tons of particulate matter, compared with 849 tons from cars, according to an analysis of Environmental Protection Agency data by Mr. Gruenwald. In 2020, during the pandemic — an era of reduced traffic and empty offices — buildings still produced more particulate matter (531 tons, compared to 491 from cars).

Because New York City is so dense, residents are constantly exposed to fumes, whether from traffic or buildings, Mr. Gruenwald said. And since getting buildings and vehicles off fossil fuels will be a gradual process, he said, the city will need multiple policies to keep on track toward meeting its climate goals. Congestion pricing is one of those policies, he and other experts argue.

“It’s another tool,” said Ms. Klopp, of Columbia, “and we will need to hone it.”