Cities that can maintain the air quality improvements seen during the coronavirus pandemic over the next few years would enjoy significant health and economic benefits, according to a new study, focused in New York City.

According to the researchers, this shows the need for wider public policies to address air pollution, and also potential solutions that can be implemented.

Like other cities around the world, New York City experienced a sharp decline in air pollution during the COVID-19 shutdown period. From March 15 to May 15, much of New York shut down, as many stayed indoors, not using their cars, and most shops and factories were closed down. It came at a high social and economic cost, but the city’s pollution was reduced sharply.

For a group of researchers from Columbia University, this provided a unique opportunity to simulate a scenario in which the city-wide air quality improvement during the shutdown was sustained over the five-year period, 2021 through 2025, allowing to estimate the public health and economic benefits.

They focused on fine particulate matter (PM2.5), tiny particles or droplets that can be found in the air, and modeled potential future health benefits to children and adults. The analysis considered outcomes in children that have not generally been accounted for in clean air benefits assessments as well as adult mortality.

Particulate matter mostly comes from combustion-related sources such as industrial emissions, transportation, wildfires, and chemical reactions of pollutants in the atmosphere. This has turned air pollution into the leading environmental cause of death around the world, according to the World Health Organization.

The researchers found a city-wide 23% improvement in PM2.5 levels during the COVID-19 shutdown months in NYC, compared to the average level for those months in 2015–2018 (the business-as-usual period). Based on the data for 2020, they analyze what would happen if we’d keep the same level of PM2.5 emissions for the following five-year period.

According to their results, thousands of lives would be saved and even more severe diseases will be prevented, with associated economic benefits ranging from $31.8 billion to $77 billion, the study showed. That’s quite a big benefit, researchers note.

“Air quality improvements from the shutdown happened as the result of a tragic situation. However, our hypothetical clean air scenario could be achieved through air pollution and climate mitigation policies, including those that support low carbon modes of transportation,” said in a statement study lead Frederica Perera.

The researchers also found that richer neighborhoods and neighborhoods with a larger Black or Latino population tended to have proportionally higher benefits from reduced PM2.5 concentrations, compared to neighborhoods with lower levels of poverty or Black or Latino populations.

The study had a significant limitation as the researchers couldn’t fully assess heterogeneity in exposure reduction based on monitoring site-specific improvement ratios. Nearly half of the available monitors that we were able to access had incomplete data for the COVID-19 shutdown period.

“This analysis should incentivize policymakers to strengthen initiatives on climate change and air pollution. The disparities across neighborhoods in underlying risk factors for air-pollution-related health outcomes should also motivate equitable policies that address these risk factors,” the researchers wrote

The study was published in the journal Environmental Research.