In the early days of the COVID-19 pandemic, while waiting outside a New York City grocery store for her turn to shop, Frederica Perera was struck by how especially “beautiful and blue” the sky looked. An air quality expert, she had a strong hunch that pandemic safety recommendations were driving down pollution levels.

“I’ve been all over the world in search of very dirty air and very clean air,” said Perera, DrPH, PhD, MPH, founding director of translational research at the Columbia Center for Children’s Environmental Health. “So my nose is a pretty good monitor.”

The clearer skies offered a unique opportunity to study the benefits of cleaner air, which Perera and colleagues quickly jumped on. Using data from air monitors stationed across New York City’s five boroughs, they estimated decreases in fine particulate matter, a pollutant emitted from burning fossil fuels and commonly known as PM2.5. Fine particulate pollution is associated with a number of poor health outcomes, including infant mortality, heart disease and neurodevelopmental disorders.

According to the study, published in February in Environmental Research, New York City experienced an average 23% improvement in fine particulate levels between March and May 2020, compared to the same time period in a previous four-year period.

New York City skyline

If sustained through 2025, researchers estimated the cumulative benefits could equal thousands of avoided cases of illness and death among adults and children, with associated economic benefits between $32 billion and $77 billion.

To generate the estimates, researchers used BenMAP, an open-source computer program that estimates the number and economic value of air pollution-related illnesses and deaths. Researchers incorporated new child health indicators into the program, such as changes in autism, childhood asthma, and adverse birth outcomes, including preterm birth and low birthweight.

In a hypothetical five-year, low-emission scenario, they found that New York City could prevent at least 420 cases of autism, more than 5,100 emergency room visits for child asthma complications, more than 900 cases of preterm birth, and nearly 2,000 new cases of child asthma. It could also save the lives of 10 infants and up to 7,800 adults.

An exploratory analysis of the distribution of benefits across different demographic groups also found that neighborhoods with higher percentages of low-income, Black and Hispanic residents — who typically face greater environmental health burdens — also experienced proportionately greater benefits in the cleaner-air scenario. However, researchers noted that the potential benefits would not eliminate existing health disparities.

Overall, Perera said the economic estimates are likely an undercount, as they mostly account for only short-term costs, such as direct medical care, and not long-term ones, such as the impacts of cognitive disability.

“This ‘natural experiment,’ tragic though the cause, has provided a hypothetical clean air scenario that can be considered aspirational — one that could be achieved through transportation, climate and environmental policies that support robust economic recovery with similarly reduced emissions,” the study stated.

Perera, a professor of environmental health sciences at Columbia University Mailman School of Public Health, said the study’s methodology is certainly applicable to other communities, depending on the availability and quality of local baseline data.

Indeed, pandemic restrictions drove down air pollution levels around the country last year. According to a January report from the Rhodium Group, for instance, U.S. greenhouse gas emissions dropped by more than 10% in 2020, marking the largest single drop in annual emissions since the post-WWII era.

Perera said estimating the health and economic benefits of maintaining that cleaner air through direct and equitable policy could be an especially persuasive argument for stronger climate action moving forward.

“Now we have a (presidential) administration paying attention to the problem of climate change, so hopefully this kind of information can be helpful,” she told The Nation’s Health. “We have the technology at hand to do this, and there are plenty of successful examples from around the world. We can get to work now to achieve this kind of decline in air pollution.”

New York City experienced almost a 25% improvement in its air quality during a three-month period measured last year during the pandemic, study says. (Photo by John Cameron, courtesy Unsplash.)