During the months of March, April, and May of 2020, New York City transformed into a new metropolis, devoid of tourists and the morning and evening rush, a near-empty epicenter of COVID-19. The city that never sleeps was resting. The streets were less crowded and, to some residents, the air felt cleaner.
In fact, the air was cleaner. A recent study in Frontiers in Environmental Science by Carlos Restrepos of New York University’s Department of Civil and Urban Engineering found that nitrogen dioxide levels dropped significantly during the city’s lockdown. Another team of researchers discovered that other hazardous air pollutants, such as ozone and particulate matter, also fell dramatically during COVID-19; they published their findings in Environmental Science and Pollution Research.
The improvement in air quality has continued, even as vehicles—the main source of air pollution in the city—repopulate the streets. An independent, preliminary analysis of current data from the state’s Department of Environmental Conservation (DEC) shows that nitrogen dioxide levels between July and September this year were 12 percent lower than during the same period in 2019.
However, some researchers, including Restrepos, said they are unsure how long pollutant levels will remain low, as more people return to work and post-pandemic life. In October and November 2021, the downward trend drops off, and the NO2 levels are again higher than the same period in 2019.
In order to sustain the improvements in air quality, significant changes in city structure and planning are necessary, environmental advocates and researchers say. Although transforming New York City’s infrastructure may be difficult, particularly in the city’s underserved communities, targeted change could affect better environmental health and overall well-being, they argue.
“We are not talking about a bright side or silver lining of the pandemic, but it was really an aspirational scenario where traffic pollution was shut down so much,” said Frederica Perera, an environmental health scientist and expert on air pollution at Columbia University, and author of the recent Environmental Health study. “Many other sources of air pollution, such as restaurants cooking and office buildings using oil burners, were reduced. We saw this drop and its benefits and we said — this kind of reduction could be achieved by means at hand.”
Perera and Restrepos said the city can maintain decreases in air pollution by further regulating tailpipe emissions, making mass transit more accessible and affordable, and implementing congestion taxing. She also argues for reworking city streets to create more pedestrian-only blocks.
“We can all agree that the value of open space and the public realm has increased under COVID-19,” Thomas Devaney, senior director of planning at the Municipal Art Society of New York, said. “I think over the next five years, we’re going to see a new New York emerge. There will be more emphasis on open streets and accessible, open space, both in the public realm and in private development.”
Permanent changes in city planning that reduce air pollution could significantly improve lung and cardiovascular health, Restrepos said. Air pollutants have been implicated in a number of respiratory diseases and an increase in premature deaths, according to the Centers for Disease Control and Prevention. The Environmental Protection Agency states, for example, that nitrogen dioxide is known to aggravate respiratory diseases, most commonly asthma, and is especially dangerous for vulnerable populations such as children and the elderly.
Perera states that air pollutants, including nitrogen dioxide, have also been linked to health effects in pregnant women and their unborn children, resulting in increased risk of low birth weight and preterm birth. Perera’s research also shows an association between air pollution and cognitive, behavioral, and mental health issues — such as low IQ, ADHD, and autism.
Restrepos’s work looked at the reduction of nitrogen dioxide pollution during the pandemic. To conduct his study, he sifted through the Metropolitan Transit Authority’s traffic data, covering the seven major bridges and tunnels that connect the boroughs of New York City. “I observed that traffic beginning in March to May  was significantly lower than in comparable periods from previous years,” Restrepos said in a phone interview.
He then compared the city’s traffic data with air quality data collected by the DEC, which measures certain pollutants every hour, on the hour, from five monitoring stations located in the Bronx, Queens, and Long Island. “I found that around the same time that traffic decreased, [nitrogen dioxide] concentrations, not surprisingly, also decreased significantly,” he said.
Restrepos’s findings came as no surprise to the DEC. As fewer cars entered the Big Apple, state officials almost immediately observed a change in the air. “We could see it the day it began happening,” Dirk Felton, a research scientist in the department’s Division of Air, said. “Looking at data before and after the 2020 lockdown, we saw very large drops for certain pollutants. Almost 50 percent for a while.”
The difference was discernible to many New Yorkers. On a recent fall day, aspiring actress Lindsay Rose said she noticed a definite improvement in air quality during COVID-19. “I remember everyone talking about how the sky looked so much bluer,” she said. “I hated people saying that New York City was dead. I loved the way it looked, how it felt, the beautiful structures restaurants built with lights hanging from the tops. New York City was ever-changing with the people and the pandemic.”
Air pollution, Restrepos said, disproportionately impacts poor neighborhoods. According to a 2019 study published in The Journal of Asthma, asthma prevalence in the Bronx is 13 percent as compared to the national asthma rate of 7.7 percent. Asthma-related emergency department visits and asthma-related hospitalizations are more than three times higher in the Bronx.
According to Restrepos, a high concentration of bus depots, waste transfer stations, and dated, emission-heavy garbage trucks in the South Bronx creates significant local air pollution problems. Perera agrees that pollution sites and polluters are often greater in underserved communities.
But implementing change in these neighborhoods has proven difficult, say both Restrepos and Perera.
“In making changes in underserved neighborhoods, you’ve got to offer good alternatives,” Perera said. “That means affordable, efficient mass transit. Making neighborhoods more safely walkable, cutting down on traffic, that will make families happy. Parks and green spaces are also very important. There’s a lot that can be done to help these neighborhoods, because they are bearing the brunt of air pollution.”