After 1 year, congestion pricing in Manhattan did not significantly improve air quality, city report finds

One year of congestion pricing in Manhattan has not dramatically improved air quality citywide, but nor has it worsened pollution in neighborhoods like the South Bronx where some predicted drivers would detour to avoid tolls.

That is the key finding of a report released Friday by New York City health officials, providing what it said was the most comprehensive evaluation to date of four traffic-related pollutants including PM 2.5, the fine particulate matter produced by fuel-burning vehicles and other sources. The report also examined nitrogen dioxide, nitric oxide and black carbon.

“Before we turned the cameras on, there was concern about the potential for increased pollution caused by drivers looking to avoid the toll,” said MTA Chair and CEO Janno Lieber, in the release. “As this study confirms, that didn’t happen, and congestion pricing is already funding additional investments to further improve air quality.”

Researchers used data from before and after congestion pricing started, along with estimates of what air quality would have been if congestion pricing had never been imposed. They examined the tolled zone in Manhattan from 60th Street south, the rest of the city as a whole and neighborhoods along the Brooklyn Queens Expressway, Cross Bronx Expressway and other roadways with the potential for increased truck traffic.

They used the Van Wyck Expressway, where there was no change in traffic because of congestion pricing, as a control.

Virtually none of the changes in measured pollution levels reached the level of statistical significance.

Traffic contributes roughly 14% of the city’s PM2.5 emissions and 20% of its nitric oxide emissions. Those levels are significant, but city Health Department researchers noted that a roughly 10% reduction in traffic volume in the tolling zone “would not substantially change air pollution compared to other sources of emissions.”

The findings differed from those of some earlier studies. A study last December by Cornell University researchers found that daily maximum particle pollution in New York City decreased by 22% after congestion pricing began. A paper by a researcher from Columbia University’s Mailman School of Health and colleagues from other institutions, however, found that congestion pricing was associated with an increase in a different measure of particle pollution in the South Bronx.

Timothy Fraser, lead author of the Cornell study and an assistant teaching professor in the university's systems engineering program, said he hoped further research would lead to even more granular findings about how congestion pricing is changing air quality and traffic patterns over time. "Traffic definitely got rerouted throughout the city. We're still trying to understand exactly where it impacted," he said. 

In January of last year, New York City became the first city in the United States to introduce tolls to reduce gridlock and air pollution and raise funds for its public transportation agency. Tolling followed decades of study, but was opposed by some officials from Long Island and suburban New Jersey. Opponents argued that the $9 toll for most vehicles driving in the zone during peak hours was excessive. The base toll is scheduled to increase to $12 in 2028.

Traffic and revenue have changed more dramatically than the pollutants tracked by researchers.

In a report released last January, the MTA said for the first 10 months of tolling, 21 million fewer vehicles entered the toll zone versus historical baseline, an 11% drop. At the same time, vehicle speed and transit ridership in the toll zone increased. Vehicles crossing the rivers surrounding Manhattan went 23% faster. During that time, MTA collected $468 million in congestion tolls, money it said went to operating expenses and capital projects like subway improvements.

By Nicholas Spangler

nicholas.spangler@newsday.comspanglernewsday

Nicholas Spangler is a general assignment reporter and has worked at Newsday since 2010.