key: cord-0806921-fds3ku96 authors: Chen, Yilin; Senthilkuma, Niru; Shen, Huizhong; Shen, Guofeng title: Environmental Inequality Deepened During the COVID-19 in the Developing World date: 2020-12-17 journal: Environ Sci Technol DOI: 10.1021/acs.est.0c06193 sha: 5a41799f900ab0d516f5a7fc20a0379335d6c5be doc_id: 806921 cord_uid: fds3ku96 nan A ir pollution is a significant environmental risk factor affecting human health. In many developing countries around the world, exposure to severe air pollution has been associated with thousands to millions of premature deaths every year from cardiovascular diseases, respiratory diseases, etc. Sources of air pollution are complex, but major sources include transportation, industrial, and energy production emissions, primarily from the burning of fossil fuels and biomass. Unequal exposure to air pollutants is often linked with disparities in socioeconomic status (SES). For example, low SES communities often reside closer to major sources of emissions including highways, power plants, and industrial facilities, and experience higher exposure levels of particulate matter (PM 2.5 ) and gas precursors such as nitrogen oxides (NO x ), sulfate dioxide (SO 2 ), and volatile organic compounds (VOCs). 1 In rural areas in many developing countries, low SES communities may experience enhanced PM 2.5 exposure from biomass and solid fuel combustion for heating and cooking. 2 The arrival of the COVID-19 pandemic has resulted in swift and radical changes in human activities, including a dramatic reduction in transportation emissions during strict lockdown periods. As a result, NO 2 was found to decline during the quarantine period over multiple countries hit by the pandemic. 3 Aside from that, the impact of the pandemic on air quality is mixed. The concentrations of PM 2.5 and other gaseous pollutants including SO 2 , VOCs, and O 3 showed more variations, 4−9 because their emission sources, such as power plants, agricultural sectors, and natural sources, has been differently affected as the transportation sector. The short-term variations in meteorological conditions and atmospheric chemical effects further complicated the changes. One relating concern is that those communities facing higher air pollution exposure may be more vulnerable to the deadly virus. A growing number of studies are reporting on the relationship between air pollution exposure and confirmed cases or fatality rates associated with COVID-19. 7−11 Wu and colleagues (2020) 7 fitted negative binomial mixed models using COVID-19 deaths and PM 2.5 at the county level in the U.S. as the outcome and exposure, respectively. After adjusting several confounding factors, they found that an increase of 1 μg/m 3 in PM 2.5 was associated with an increase of 5% (2−15% as 95% CI) in the COVID-19 death rate. Similar links between ambient air pollution exposure and COVID-19 incidence and mortality was also reported in China, 8, 9, 11 India, 3 Pakistan, 11 and Indonesia. 11 It has been suggested that the ambient aerosols facilitate the transmission of the virus. 8 A few studies also proposed biologically plausible pathways to explain the association. 12, 13 One common belief is that exposure to air pollutants compromises people's cardiovascular and respiratory systems, making them more vulnerable to the disease. One caveat of these, some if not all, studies is that major confounding factors have not been adequately controlled. Although some efforts have been made to control factors like temperature, availability and accessibility of medical resources, socioeconomic conditions, demographic characteristics (such as population density and distribution) at an aggregated level, individual-level information characterizing lifestyle and vulnerability (smoking, diet, working condition, medical history, etc.) is missing. Without such information, it is hard to compare or extrapolate the association found in one location to other places hit by the pandemic. Another issue with these studies is that they relied on ambient air pollution from stationary air monitoring sites as an indicator of exposure, although it has been recognized that this can bias the exposure assessment due to high spatiotemporal variations in air pollutant concentrations and because people spent more time indoors during lockdown periods. As the pandemic goes on, COVID-19 gets widely spreading in rural areas in developing countries. The observed positive relationship between enhanced air pollutant exposures and COVID-19 deaths indicates that the pandemic may be further deepening environmental inequality. Over half of the population in the developing world still rely on solid fuel as their household energy source, exposing to a high level of PM 2.5 daily. Besides previous chronic exposure to ambient NO 2 and PM 2.5 , indoor air pollution exposure in developing countries would increase during quarantine, especially in those households heavily relying on solid fuels. 14 As a known leading environmental risk factor for many diseases and premature death, household solid-fuel use may increase the risk to develop severe symptoms among the infected population in the developing world. Unfortunately, to the best of our knowledge, the association between household air pollution and COVID-19 in the developing world has not been well assessed. We encourage studies to fill the gap. Knowing the association is important to guide effective policies and resource allocation to support people in the developing world through this pandemic. In the long term, the global community should continue to focus efforts on promoting and enabling clean affordable energies in the developing world. The pandemic has revealed that the efforts will not only close the environmental inequality but may also protect the low SES population from COVID-19 and other diseases. We recognize that transiting to clean energy is not an easy process in the developing world. Both transitional methods such as the promotion of cleaner stoves, cleaner solid fuels, and long-term plans to build infrastructure to provide access to gas and electricity in rural regions need to be combined to facilitate the transition. Socioeconomic Disparities and Air Pollution Exposure: a Global Review Millions Dead: How Do We Know and What Does It Mean? Methods Used in the Comparative Risk Assessment of Household Air Pollution Impact of Coronavirus Outbreak on NO 2 Pollution Assessed Using TROPOMI and OMI Observations Unexpected air pollution with marked emission reductions during the COVID-19 outbreak in China COVID-19 lockdowns cause global air pollution declines COVID-19 lockdowns cause global air pollution declines Exposure to air pollution and COVID-19 mortality in the United States: A nationwide cross-sectional study; medRxiv Air pollution and temperature are associated with increased COVID-19 incidence: A time series study Association between short-term exposure to air pollution and COVID-19 infection: Evidence from China Exposure to Nitrogen Dioxide (NO 2 ) from Vehicular Emission Could Increase the COVID-19 Pandemic Fatality in India: A Perspective Air pollution aggravating COVID-19 lethality? Exploration in Asian cities using statistical models. 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