COVID-19 as a Factor Influencing Air Quality? A City Study in China

Chengming Li,Zhihao Cui,Zhaoting Ma,Zhaoxin Dai,Hui Shang

doi:10.4209/aaqr.210080

Abstract

To prevent the spread of coronavirus disease 2019 (COVID-19), which emerged in late December 2019, the Chinese government immediately adopted lockdown measures, such as restricting traffic and closing factories. By analyzing the spatiotemporal distribution of the air quality index (AQI) values in Dongying, a city dominated by the petrochemical industry (specifically, petroleum exploration), during February 2020, when the strictest measures were in force, this study investigates the effect of short-term lockdowns on air quality. We observed a statistically significant reduction in the monthly average AQI—24.6%, or an absolute decrease of 25.4—compared to February 2019. Additionally, the difference between the maximum and the minimum hourly average AQI dropped to almost one-third of the value that in the normal time during winter. We also assessed the influence of meteorological factors and industrial exhaust emissions. Quantitative analysis revealed a strong positive correlation (p < 0.01) between the AQI and exhaust emissions, confirming the latter’s contribution to air pollution. However, this contribution shrunk by approximately 38.3% during February 2020. Our results indicate that the improvement in air quality was related to traffic reduction and enterprise closures during the lockdown, which only marginally affected the spatial distribution of the AQI values. This research serves as a reference for controlling air pollution in Dongying and areas with similar conditions.

Highlights

Due to rapid urbanization and industrialization, interest in environmental monitoring in China has greatly increased (Zhou et al, 2016)
Our results indicate that the improvement in air quality was related to traffic reduction and enterprise closures during the lockdown, which only marginally affected the spatial distribution of the air quality index (AQI) values
How the air quality of Dongying, a city known for petroleum exploration, was affected by factory closure during the lockdown is unknown

Summary

Introduction

Due to rapid urbanization and industrialization, interest in environmental monitoring in China has greatly increased (Zhou et al, 2016). Air pollution can cause respiratory, cardiovascular, and cerebrovascular diseases through gas exchange in the lungs (Mannucci and Franchini, 2017; Glencross et al, 2020). It can significantly reduce visibility and cause smog, which is inconvenient for residents’ travel. The air quality index (AQI) is a dimensionless index describing air quality; it can be obtained by combining the levels of six major pollutants, namely fine particulate matter (PM2.5), coarse particulate matter (PM10), sulfur dioxide (SO2), ozone (O3), nitrogen dioxide (NO2), and carbon monoxide (CO). Identifying the spatiotemporal distribution of AQI characteristics is essential for targeted control of air pollution (Masiol et al, 2018)

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Discussion

Conclusion