Exposure Risk of Global Surface O3 During the Boreal Spring Season

Abstract

Surface ozone (O3) is an oxidizing gaseous pollutant; long-term exposure to high O3 concentrations adversely affects human health. Based on daily surface O3 concentration data, the spatiotemporal characteristics of O3 concentration, exposure risks, and driving meteorological factors in 347 cities and 10 major countries (China, Japan, India, South Korea, the United States, Poland, Spain, Germany, France, and the United Kingdom) worldwide were analyzed using the MAKESENS model, Moran’ I analysis, and Generalized additive model (GAM). The results indicated that: in the boreal spring season from 2015 to 2020, the global O3 concentration exhibited an increasing trend at a rate of 0.6 μg/m3/year because of the volatile organic compounds (VOCs) and NOx changes caused by human activities. Due to the lockdown policies after the outbreak of COVID-19, the average O3 concentration worldwide showed an inverted U-shaped growth during the study period, increasing from 21.9 μg/m3 in 2015 to 27.3 μg/m3 in 2019, and finally decreasing to 25.9 μg/m3 in 2020. According to exposure analytical methods, approximately 6.32% of the population (31.73 million people) in the major countries analyzed reside in rapidly increasing O3 concentrations. 6.53% of the population (32.75 million people) in the major countries were exposed to a low O3 concentration growth environment. Thus, the continuous increase of O3 concentration worldwide is an important factor leading to increasing threats to human health. Further we found that mean wind speed, maximum temperature, and relative humidity are the main factors that determine the change of O3 concentration. Our research results are of great significance to the continued implementation of strict air quality policies and prevention of population hazards. However, due to data limitations, this research can only provide general trends in O3 and human health, and more detailed research will be carried out in the follow-up.