Quantifying anomalies of air pollutants in 9 U.S. cities during 2020 due to COVID-19 lockdowns and wildfires based on decadal trends

Peischl, J.; Aikin, K. C.; McDonald, Brian; Harkins, Colin; Middlebrook, A. M.; Langford, A. O.; Cooper, O. R.; Chang, Kai‐Lan; Brown, Steven S.

doi:10.1525/elementa.2023.00029

Cited by 4 publications

(1 citation statement)

References 55 publications

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“…By analyzing seasonal averages of the anomalies, the Western US rural (WUS_R) sites experienced persistent negative anomalies for MAM and JJA 2020 (−6% and −5%, respectively), and for MAM 2021 (−2%), while JJA 2021 was characterized by a strong positive anomaly (2.8 ppb, 6%). Late summer 2020 was characterized by the spread of wildfires in the Western US (Filonchyk et al, 2022;Jaffe et al, 2022;Peischl et al, 2023;Langford et al, 2023), resulting in positive average anomalies for August and September 2020 (2.3 and 2.5 ppb, i.e., 5% and 6%, respectively) for several sites (see Fig. S4).…”

Section: Quantification Of the Anomaliesmentioning

confidence: 99%

Fingerprints of the COVID-19 economic downturn and recovery on ozone anomalies at high-elevation sites in North America and Western Europe

Putero

Cristofanelli

Chang

et al. 2023

Preprint

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Abstract. With a few exceptions, most studies on tropospheric ozone (O3) variability during and following the COVID-19 economic downturn focused on high-emission regions or urban environments. In this work, we investigated the impact of the societal restriction measures during the COVID-19 pandemic on surface O3 at several high-elevation sites across North America and Western Europe. Monthly O3 anomalies were calculated for 2020 and 2021, with respect to the baseline period 2000–2019, to explore the impact of the economic downturn initiated in 2020 and its recovery in 2021. In total, 41 high-elevation sites were analyzed: 5 rural or mountaintop stations in Western Europe, 19 rural sites in the Western US, 4 sites in the Western US downwind of highly polluted source regions, 4 rural sites in the eastern US, plus 9 mountaintop or high-elevation sites outside Europe and the United States to provide a “global” reference. In 2020, the European high-elevation sites showed persistent negative surface O3 anomalies during spring (March–May, i.e., MAM) and summer (June–August, i.e., JJA), except for April. The pattern was similar in 2021, except for June. The rural sites in the Western US showed similar behavior, with negative anomalies in MAM and JJA 2020 (except for August), and MAM 2021. The JJA 2021 seasonal average was influenced by strong positive anomalies in July, due to large and widespread wildfires across the Western US. The polluted sites in the Western US showed negative O3 anomalies during MAM 2020, and a slight recovery in 2021, resulting in a positive average anomaly for MAM 2021 and a pronounced month-to-month variability in JJA 2021 anomalies. The Eastern US sites were also characterized by below average O3 for both MAM and JJA 2020, while in 2021 the negative values exhibited an opposite structure compared to the Western US sites, which were influenced by wildfires. Concerning the rest of the World, a global picture could not be drawn, as the sites, spanning a range of different environments, did not show consistent anomalies, with a few sites not experiencing any notable variation. Moreover, we also compared our surface anomalies to the variability of mid-tropospheric O3 detected by the IASI satellite instrument. Negative anomalies were observed by IASI, consistent with published satellite and modeling studies, suggesting that the anomalies can be largely attributed to the reduction of O3 precursor emissions in 2020.

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Section: Quantification Of the Anomaliesmentioning

confidence: 99%

Fingerprints of the COVID-19 economic downturn and recovery on ozone anomalies at high-elevation sites in North America and Western Europe

Putero

Cristofanelli

Chang

et al. 2023

Preprint

View full text Add to dashboard Cite

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Early Season 2023 Wildfires Generated Record‐Breaking Surface Ozone Anomalies Across the U.S. Upper Midwest

Cooper,

Chang,

Bates

et al. 2024

Geophysical Research Letters

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During summer 2023 Canada experienced its most intense wildfire season on record. Smoke plumes from these fires advected across the United States (U.S.) Upper Midwest, producing regional scale surface enhancements of PM2.5 and ozone, as recorded by the U.S. surface monitoring network. These events are notable because they occurred early in the fire season (May 15‐June 30), and they produced the highest regional‐scale surface ozone levels ever recorded across the northern tier of the U.S. during early (May–June) or late (July‐August) summer. Specifically, the Upper Midwest 50th ozone percentile was greater than in any other year since 1995, when the ozone monitoring network had sufficient coverage to assess regional‐scale ozone levels; the 90th percentile was the highest since 2002. Satellite and aircraft measurements demonstrate the availability of ozone precursors and ozone production within the smoke plumes.

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Deciphering decadal urban ozone trends from historical records since 1980

Wang,

Lu,

Palmer

et al. 2024

National Science Review

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Ozone pollution is a major environmental threat to human health. Timely assessment of ozone trends is crucial for informing environmental policy. Here we show that for the most recent decade (2013–2022) in the Northern Hemisphere, warm-season (April-September) mean daily 8-h average maximum (MDA8) ozone increases much faster in urban regions with top ozone levels (mainly in North China Plain, 1.2 ± 1.3 ppbv year−1) than that in other low-ozone regions (0.2 ± 0.9 ppbv year−1). These trends widen the ozone differences across urban regions, and increase extreme pollution levels and health threats from a global perspective. Comparison of historical trends in different urban regions reveals that, ozone increases in China during 2013–2022 differ in magnitude and mechanisms from historical periods in other regions since 1980. This reflects a unique chemical environment characterized by exceptionally high nitrogen oxides and aerosol concentrations, where reducing ozone precursor emissions leads to substantial ozone increase. Ozone increase in China has slowed down in 2018–2022 compared to 2013–2017, driven by ongoing emission reductions but with ozone-favorable weather conditions. Historical ozone evolution in Japan and South Korea indicates that ozone increases should be suppressed with continuous emission reduction. Increasing temperature and associated wildfires have also reversed ozone decreases in the US and Europe with anthropogenic ozone control slowing down in recent decades.

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Quantifying anomalies of air pollutants in 9 U.S. cities during 2020 due to COVID-19 lockdowns and wildfires based on decadal trends

Cited by 4 publications

References 55 publications

Fingerprints of the COVID-19 economic downturn and recovery on ozone anomalies at high-elevation sites in North America and Western Europe

Fingerprints of the COVID-19 economic downturn and recovery on ozone anomalies at high-elevation sites in North America and Western Europe

Early Season 2023 Wildfires Generated Record‐Breaking Surface Ozone Anomalies Across the U.S. Upper Midwest

Deciphering decadal urban ozone trends from historical records since 1980

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