New York City (NYC) experienced a sharp decline in air pollution during the COVID-19 shutdown period (March 15, 2020 to May 15, 2020)—albeit at high social and economic costs. It 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 us to estimate the potential public health benefits to children and adults and their associated economic benefits.

We focused on fine particulate matter (PM_2.5) and modelled 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, including preterm birth, term low birthweight, infant mortality, child asthma incidence, child asthma hospital admissions and emergency department visits, autism spectrum disorder, as well as adult mortality.

We estimated a city-wide 23% improvement in PM_2.5 levels during the COVID-19 shutdown months compared to the average level for those months in 2015-2018 (the business as usual period). Based on the data for 2020, we extrapolated the ambient levels of PM_2.5 for the following five-year period. The estimated cumulative benefits for 2021-2025 included thousands of avoided cases of illness and death, with associated economic benefits from $31.8 billion to $77 billion.

This “natural experiment,” tragic though the cause, resulted in a 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.

在COVID-19关闭期间（2020年3月15日至2020年5月15日），尽管纽约市（NYC）付出了巨大的社会和经济代价，但空气污染却急剧减少。它提供了一个独特的机会来模拟一种情景，即在关闭期间的整个五年内（从2021年到2025年），全市空气质量的改善将得以持续，从而使我们能够估计对儿童和成人及其相关人群的潜在公共健康利益经济效益。

我们专注于细颗粒物（PM _2.5）并模拟了对儿童和成人未来的潜在健康益处。该分析考虑了通常没有在清洁空气收益评估中考虑的儿童结局，包括早产，足月低出生体重，婴儿死亡率，儿童哮喘发病率，儿童哮喘医院入院和急诊就诊，自闭症谱系障碍以及成人死亡率。

我们估计，在COVID-19停产月份中，全市PM _2.5水平比2015-2018年（照常营业）的平均水平提高了23％。根据2020年的数据，我们推断出接下来五年的PM _2.5的环境水平。2021-2025年的估计累积收益包括数千起避免的疾病和死亡案例，相关经济收益从318亿美元增加到770亿美元。

这种“自然实验”虽然是不幸的，但却导致了令人生畏的清洁空气情景，可以通过交通，气候和环境政策来实现，以支持强劲的经济复苏并减少排放。