Did air quality actually improve in New York City during the spring coronavirus shutdown? Debate about that question is developing between scientists and government officials, with studies arriving at sharply different conclusions.
The New York City Department of Environmental Conservation and a research team from the State University of New York’s College of Environmental Science and Forestry offer contradictory findings on the quality of air during the first half of 2020.
The SUNY study, published in Science of the Total Environment last month, showed that the city’s air quality didn’t change much at the height of the lockdown in April, when travel and commuting dropped drastically and most businesses shut down.
Internationally, studies have demonstrated that air quality improved in countries like India and France because of social distancing and shutdown measures during the pandemic. But did that happen in New York?
‘’There is a seasonal decline in air pollution in the whole of New York City for the last five years, but not because of the lockdown,’’ said Jamie Mirowsky, assistant professor of chemistry and a co-author of the study.
Her team reviewed the city’s air quality data over a five-year period and noted seasonal declines in pollution, which remained constant during the health crisis.
Their findings, however, contradict data collected by the city. Press officer Maureen Wren said experts in the Department of Environmental Conservation, using satellite observations, did detect reduced pollutants during the lockdown and over time, after accounting for other variables.
‘’The region’s air quality responded to reductions in emissions from reduced vehicle traffic and industrial activity. Changes in emissions are not easily detected and are impacted by other factors,’’ she said in an email, without supplying details on the amount of the decreases. The department did not respond to questions about the SUNY study.
Mirowsky refused to be drawn into controversy, saying she had not read the city’s findings. She pointed out that the SUNY study accounted for both short- and longer-term changes in air quality and found that concentrations of particulate matter (PM2.5) and nitrogen dioxide (NO2) decreased from January to May 2020. But the decrease was similar in magnitude to that observed during the same time in the previous five years.
‘’This suggests that no or minimal improvements in NYC’s air quality were observed as a result of the COVID-19 government-backed shutdowns,’’ Mirowsky said.
Particulate matter, all solid and liquid particles suspended in air, includes both organic and inorganic substances like dust, pollen, soot, smoke and liquid droplets, many hazardous to humans. They also reduce visibility and cause the air to appear hazy when levels are elevated.
“Regardless of the year we got our data from, the PM2.5 values were higher in the beginning of January compared to the later data points, which end in May. This decrease in PM2.5 as you move from January to May is commonly seen in New York City,” Mirowsky said.
Nitrogen dioxide causes a range of harmful effects including increased inflammation of the airways and reduced lung function.
The American Lung Association declined to comment on the controversy, saying most lung cases they dealt with during the lockdown were from people staying at home and rarely venturing outside.
‘’ Most of the people we worked with during the lockdown were largely people sheltering at home and that does not confirm nor deny that air pollution went down,’’ said Jennifer Solomon, a lung health expert with the association.
The state health department estimates that pollution in New York State annually causes more than 2,500 deaths, 2,000 hospital admissions for lung and heart conditions, and approximately 6,000 emergency department visits for asthma in children and adults.
The same estimates show that a modest reduction of 10% in particulate matter levels could prevent more than 300 premature deaths, 200 hospital admissions and 600 emergency department visit each year.
With or without the lockdown, ‘’the latest air survey has shown a significant improvement over the past nine years in the city’s air,” said Samantha Keitt, a spokesperson for the city health department. “We still have more work to do to ensure that all New Yorkers can breathe the same clean air. ‘’
She attributed the improvement to stronger clean air laws and regulations. The health department’s community air surveys from 2009 to 2017 found decreases in nitrogen dioxide (30%), nitric oxide (26%) and black carbon (44%).
The largest declines have been observed for sulfur dioxide, due largely to city and state boiler regulations. Winter average levels have declined by 96%. But average summer ozone levels have remained stable.
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