NOx Emission Reduction and Recovery during COVID-19 in East China

Abstract

Since its first confirmed case at the end of 2019, COVID-19 has become a global pandemic in three months with more than 1.4 million confirmed cases worldwide, as of early April 2020. Quantifying the changes of pollutant emissions due to COVID-19 and associated governmental control measures is crucial to understand its impacts on economy, air pollution, and society. We used the WRF-GC model and the tropospheric NO2 column observations retrieved by the TROPOMI instrument to derive the top-down NOx emission change estimation between the three periods: P1 (January 1st to January 22nd, 2020), P2 (January 23rd, Wuhan lockdown, to February 9th, 2020), and P3 (February 10th, back-to-work day, to March 12th, 2020). We found that NOx emissions in East China averaged during P2 decreased by 50% compared to those averaged during P1. The NOx emissions averaged during P3 increased by 26% compared to those during P2. Most provinces in East China gradually regained some of their NOx emissions after February 10, the official back-to-work day, but NOx emissions in most provinces have not yet to return to their previous levels in early January. NOx emissions in Wuhan, the first epicenter of COVID-19, had no sign of emission recovering by March 12. A few provinces, such as Zhejiang and Shanxi, have recovered fast, with their averaged NOx emissions during P3 almost back to pre-lockdown levels.

Analysis of the scientific production of the effect of COVID-19 on the environment: A bibliometric study

“…Their results reveal that levels of polluting gases fell by about 45% after two weeks. Similar findings are reported in Thailand ( Stratoulias and Nuthammachot, 2020 ), China and Japan ( Ma and Kang, 2020 ; Zhang et al, 2020 ), Ecuador ( Zalakeviciute et al, 2020 ), Iran ( Broomandi et al, 2020 ), Milan, Italy ( Collivignarelli et al, 2020 ) and Morocco ( Otmani et al, 2020 ). Siciliano et al (2020) and Zhao et al (2020) , in turn, identified noteworthy increases in ozone concentrations (O 3 ) during the measures of social distancing adopted respectively by Brazil and China.…”

Changes in air quality and human mobility in the USA during the COVID-19 pandemic

“…However, emissions from residential heating and industry remained steady or slightly declined (Chen et al 2020). Using satellite data, Zhang et al (2020) and the National Center for Atmospheric Research (Worden et al 2020) reported a 70% and 50% decrease in NO x concentrations in Eastern China, respectively. Bao and Zhang (2020) showed an average of 7.8% decrease in the Air Quality Index over 44 cities in northern China.…”

Impacts of COVID-19 on a Transitioning Energy System, Society, and International Cooperation

“…While COVID-19 restrictions have reduced carbon emissions, alongside other GHGs, pollutants, and aerosols, the easing of these restrictions is likely to see an uptick in emission levels. This has already been noted in parts of China, the earliest affected region of the pandemic [11,12]. One suggested approach emerging from the pandemic is the concept of 'glocalization'.…”

“…Focusing on nitrogen oxides (NO x ), it was confirmed that levels decreased considerably (~50%) for most provinces compared to pre-COVID-19 lockdowns, and only moderately rebounded (~26%) after back-to-work orders were issued for most eastern Chinese provinces. Wuhan was an exception, where NO x levels remained low, even into March 2020 [12]. Considering the impact of reduced mobility, an almost 70% reduction in human mobility in 44 cities in northern China lead to significant decreases in SO 2 (6.76%), PM 2.5 , and PM 10 (5.93% and 13.66%), NO 2 (24.67%) and CO (4.58%), highlighting the flow-on impacts of decreased mobility on industrial and commercial activities linked to our daily lives [13].…”