Impact of the COVID-19 pandemic and control measures on air quality and aerosol light absorption in Southwestern China

Chen, Yang; Zhang, Shumin; Peng, Chao; Shi, Guangming; Tian, Mi; Huang, Ru‐Jin; Guo, Dongmei; Wang, Huanbo; Yao, Xin‐Kan; Yang, Fumo

doi:10.1016/j.scitotenv.2020.141419

Cited by 53 publications

(58 citation statements)

References 41 publications

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“…China: (Agarwal et al, 2020;Chauhan and Singh, 2020;Chen et al, 2020a;Chen et al, 2020c;Chen et al, 2020d;Fan et al, 2020;G Huang and Sun, 2020;Lian et al, 2020;Liu et al, 2020c;Miyazaki et al, 2020;Nichol et al, 2020;Pei et al, 2020;Shakoor et al, 2020;Shi and Brasseur, 2020;Silver et al, 2020;Wan et al, 2020;Wang et al, 2020a;Wang et al, 2020b;Wang et al, 2020f;Xu et al, 2020c;Zhang et al, 2020a;Yuan et al, 2021) Other: (Ghahremanloo et al, 2020;Han et al, 2020;Ju et al, 2020;Ma and Kang, 2020;Zhang et al, 2020b) South Asia India: (Bedi et al, 2020;Beig et al, 2020;Biswal et al, 2020;Chatterjee et al, 2020;Gautam et al, 2020;Harshita and Vivek, 2020;Jain and Sharma, 2020;Kant et al, 2020;Kumari and Toshniwal, 2020;Panda et al, 2020;Ranjan et al, 2020;Selvam et al, 2020;Sharma et al, 2020a;Siddiqui et al, 2020;Singh and Chauhan, 2020;…”

Section: East Asiaunclassified

The global impacts of COVID-19 lockdowns on urban air pollution

Gkatzelis

Gilman

Brown

et al. 2021

Elementa: Science of the Anthropocene

133

154

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The coronavirus-19 (COVID-19) pandemic led to government interventions to limit the spread of the disease which are unprecedented in recent history; for example, stay at home orders led to sudden decreases in atmospheric emissions from the transportation sector. In this review article, the current understanding of the influence of emission reductions on atmospheric pollutant concentrations and air quality is summarized for nitrogen dioxide (NO2), particulate matter (PM2.5), ozone (O3), ammonia, sulfur dioxide, black carbon, volatile organic compounds, and carbon monoxide (CO). In the first 7 months following the onset of the pandemic, more than 200 papers were accepted by peer-reviewed journals utilizing observations from ground-based and satellite instruments. Only about one-third of this literature incorporates a specific method for meteorological correction or normalization for comparing data from the lockdown period with prior reference observations despite the importance of doing so on the interpretation of results. We use the government stringency index (SI) as an indicator for the severity of lockdown measures and show how key air pollutants change as the SI increases. The observed decrease of NO2 with increasing SI is in general agreement with emission inventories that account for the lockdown. Other compounds such as O3, PM2.5, and CO are also broadly covered. Due to the importance of atmospheric chemistry on O3 and PM2.5 concentrations, their responses may not be linear with respect to primary pollutants. At most sites, we found O3 increased, whereas PM2.5 decreased slightly, with increasing SI. Changes of other compounds are found to be understudied. We highlight future research needs for utilizing the emerging data sets as a preview of a future state of the atmosphere in a world with targeted permanent reductions of emissions. Finally, we emphasize the need to account for the effects of meteorology, emission trends, and atmospheric chemistry when determining the lockdown effects on pollutant concentrations.

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Section: East Asiaunclassified

The global impacts of COVID-19 lockdowns on urban air pollution

Gkatzelis

Gilman

Brown

et al. 2021

Elementa: Science of the Anthropocene

133

154

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“…Beyond gaseous pollutants and AOD, there are some studies analyzing the changes in BC concentrations during the lockdown period [26,[38][39][40][41][42], which reported significant reductions (30-70%), but with large variability among regions. On the contrary, only a few works examined the changes in aerosol spectral absorption [43,44], while there is a lack of studies related to changes in spectral-scattering and single-scattering albedo (SSA).…”

Section: Introductionmentioning

confidence: 99%

Assessment of the COVID-19 Lockdown Effects on Spectral Aerosol Scattering and Absorption Properties in Athens, Greece

et al. 2021

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COVID-19 is evolving into one of the worst pandemics in recent history, claiming a death toll of over 1.5 million as of December 2020. In an attempt to limit the expansion of the pandemic in its initial phase, nearly all countries imposed restriction measures, which resulted in an unprecedented reduction of air pollution. This study aims to assess the impact of the lockdown effects due to COVID-19 on in situ measured aerosol properties, namely spectral-scattering (bsca) and absorption (babs) coefficients, black carbon (BC) concentrations, single-scattering albedo (SSA), scattering and absorption Ångström exponents (SAE, AAE) in Athens, Greece. Moreover, a comparison is performed with the regional background site of Finokalia, Crete, for a better assessment of the urban impact on observed differences. The study examines pre-lockdown (1–22 March 2020), lockdown (23 March–3 May 2020) and post-lockdown (4–31 May 2020) periods, while the aerosol properties are also compared with a 3–4 year preceding period (2016/2017–2019). Comparison of meteorological parameters in Athens, between the lockdown period and respective days in previous years, showed only marginal variation, which is not deemed sufficient in order to justify the notable changes in aerosol concentrations and optical properties. The largest reduction during the lockdown period was observed for babs compared to the pre-lockdown (−39%) and to the same period in previous years (−36%). This was intensified during the morning traffic hours (−60%), reflecting the large decrease in vehicular emissions. Furthermore, AAE increased during the lockdown period due to reduced emissions from fossil-fuel combustion, while a smaller (−21%) decrease was observed for bsca along with slight increases (6%) in SAE and SSA values, indicating that scattering aerosol properties were less affected by the decrease in vehicular emissions, as they are more dependent on regional sources and atmospheric processing. Nighttime BC emissions related to residential wood-burning were slightly increased during the lockdown period, with respect to previous-year means. On the contrary, aerosol and pollution changes during the lockdown period at Finokalia were low and highly sensitive to natural sources and processes.

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“…The model assumes that b abs is the sum of optical absorption coefficients of biomass burning (b abs,bb ) and fossil fuel (b abs,ff ) fractions, as given in Equations (6) and (7). b abs (370 nm) = b abs (370 nm) ff + b abs (370 nm) bb (6) b abs (880 nm) = b abs (880 nm) ff + b abs (880 nm) bb (7) The b abs,ff and b abs,bb are computed for the wavelengths of 370 and 880 nm using Equations (8) and (9), respectively, by assuming that b abs,bb is negligible at 880 nm [68,76]. The absorption exponents for fossil fuel (α ff ) and for biomass (α bb ) were used as 1 and 2, respectively.…”

Section: Black Carbon Measurements and Data Treatmentmentioning

confidence: 99%

“…A few studies have been conducted to reveal the impacts of COVID-19 lockdown measures on ambient BC concentrations. Reported studies from the USA [66], Italy [67], China [68,69], and India [70] revealed that BC concentrations reduced within the range between 22% and 71% in response to lockdown measures to combat the COVID-19 pandemic.…”

Section: Introductionmentioning

confidence: 99%

Source Apportionment of Ambient Black Carbon during the COVID-19 Lockdown

Anıl

Alagha

2020

IJERPH

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Black carbon (BC) particles being emitted from mobile and stationary emission sources as a result of combustion activities have significant impacts on human health and climate change. A lot of social activities have been halted during the COVID-19 lockdowns, which has evidently enhanced the ambient and indoor air quality. This paper investigates the possible emission sources and evaluates the meteorological conditions that may affect the dispersion and transport of BC locally and regionally. Ground-level equivalent BC (eBC) measurements were performed between January 2020 and July 2020 at a university campus located in Dammam city of the Kingdom of Saudi Arabia (KSA). The fossil fuel (eBCff) and biomass burning (eBCbb) fractions of total eBC (eBCt) concentrations were estimated as 84% and 16%, respectively, during the entire study period. The mean eBCbb, eBCff, and eBCt concentrations during the lockdown reduced by 14%, 24%, and 23%, respectively. The results of statistical analyses indicated that local fossil fuel burning emissions and atmospheric conditions apparently affected the observed eBC levels. Long-range potential source locations, including Iraq, Kuwait, Iran, distributed zones in the Arabian Gulf, and United Arab Emirates and regional source areas, such as the Arabian Gulf coastline of the KSA, Bahrain, and Qatar, were associated with moderate to high concentrations observed at the receptor site as a result of cluster analysis and concentration-weighted trajectory analysis methods.

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Impact of the COVID-19 pandemic and control measures on air quality and aerosol light absorption in Southwestern China

Cited by 53 publications

References 41 publications

The global impacts of COVID-19 lockdowns on urban air pollution

The global impacts of COVID-19 lockdowns on urban air pollution

Assessment of the COVID-19 Lockdown Effects on Spectral Aerosol Scattering and Absorption Properties in Athens, Greece

Source Apportionment of Ambient Black Carbon during the COVID-19 Lockdown

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