As health systems around the world struggle to respond to the coronavirus disease 2019 (COVID-19) pandemic, the crisis has brought into sharp focus several important global environmental health issues. It is becoming clear that environmental and climate factors help shape the landscape within which COVID-19 proliferates around the world, influencing the public health response to the pandemic and interacting with existing environmental health disparities.
Ongoing efforts to understand the nature and behavior of SARS-CoV-2, the novel coronavirus that causes COVID-19 respiratory illness, include research on the role of environmental factors in COVID-19 infection and disease severity. The Research Spotlight highlights several of these articles in detail. A few preliminary studies, including one by Sajadi, et. al., and another by Wu, et. al., suggest the spread of the infection is associated with temperature and humidity. In addition to informing public health responses over the next few months, these findings also suggest there may be seasonality of COVID-19 disease transmission, similar to influenza, which tends to peak at times of colder temperatures and low humidity. There are preliminary indications that wind and ultraviolet (UV) light may potentially be associated with COVID-19. Studies by Islam, et. al. and Gunthe, et. al., suggest increased wind speed and greater UV index, respectively, are associated with fewer cases. These results indicate climate variables may be useful to predict periods of lower or higher intensity of COVID-19 spread in local communities, which has significant policy, communication, and resource implications.
Early studies show that other environmental factors may also affect disease severity. Poor air quality appears to be associated with more severe health outcomes in infected individuals. A recent cross-sectional study by researchers Wu, et al., at Harvard University shows long-term exposure to fine particulate matter (PM2.5) is linked to higher mortality from COVID-19. These observations have serious implications for areas of the world such as India and other parts of Southeast Asia that have historically suffered from consistently higher levels of air pollution.
Climate and weather extremes not only may affect transmission of the SARS-CoV-2 virus, but also the ability of health systems to respond effectively. As the frequency and severity of some extreme weather disasters increase, the COVID-19 pandemic illuminates the special challenges to health systems of concurrent events and cumulative hazards and stressors. With the United States entering the season of heat waves, tornadoes, and hurricanes, public health systems need to be able to deal with the ongoing COVID-19 epidemic, the health consequences of heat and extreme weather, and the interactions between the two, such as impacts of heat and extreme weather on health care workers who may be working in vulnerable temporary facilities. The situation also poses critical public health risk management and risk communication challenges. How do you protect people, especially those in higher COVID-19 risk categories, if they have to move to emergency shelters or cooling centers? How do you ensure public health messaging in a time of pandemic and risk tradeoffs is clear and motivates people to take effective protective actions?
The Centers for Disease Control and Prevention (CDC) has stepped up to produce guidance for public health departments on managing concurrent threats, including recommendations for hurricane preparation and best practices for cooling centers during the pandemic. The Global Heat Health Information Network (GHHIN) has many resources related to COVID-19 and extreme heat that highlight useful information for mitigating health risks and offer specific guidance relevant to vulnerable populations, health workers, and city planners and local governments. Programs like the NIEHS Disaster Research Response Program provide support and infrastructure for conducting timely research to better understand health outcomes and the effectiveness of interventions.
The extensive societal changes resulting from public health mitigation measures have raised another interesting environmental health research question: how have air pollution reductions associated with the COVID-19 response affected local disease severity and other health outcomes? With the majority of businesses closed to the public and people encouraged to stay safe at home, air pollution has visibly cleared in many places around the world. Noticeable reductions in aerosol levels can be observed from satellite imagery, in particular, decreases in nitrogen dioxide and PM2.5 air pollution. This “natural experiment” in reduction in air pollution exposure offers important opportunities for research on changes in health outcomes around the world.
To foster research on how past and present environmental exposures may impact COVID-19 susceptibility, disease severity, and disease progression, NIEHS has issued a Notice of Special Interest (NOSI). The NOSI lays out 11 possible research interests, ranging from studying the effects of environmental exposures on individual COVID-19 susceptibility to investigations of the respiratory microbiome in COVID-19 and the use of other “omic” approaches to characterizing disease risk and progression. The NOSI also identifies the roles of climate and weather-related factors and environmental health disparities in COVID-19 as important interests.
NIEHS is working alongside various global health, health security, and infectious disease modeling communities to help generate important knowledge about the interactions between COVID-19 and the environment in the short term and more broadly, the interactions between emerging infectious diseases and the environment. NIEHS participates in the Group on Earth Observations (GEO) Health Community of Practice, collaborating with researchers at the Johns Hopkins University on research linking satellite observations to COVID-19 incidence data to explore connections between weather and transmission of COVID-19, and researchers at the European Commission Joint Research Centre looking at Copernicus Atmosphere Monitoring Service (CAMS) air pollution data and COVID-19 in Italy. The lessons learned and findings from these international collaborations will provide valuable information on predictive capabilities, preventative measures, and strategies for intervention in the event of future public health disasters or pandemics.
“The COVID-19 pandemic has brought out synergies between infectious disease epidemiology and environmental health in a more robust way than perhaps since the great pandemics of the past two centuries,” said John Balbus, M.D., NIEHS Senior Advisor for Public Health. “Conversations taking place in the global health community suggest that the experience of facing this pandemic may help foster more collaboration among those working on global health security, emergency preparedness, and disaster risk reduction, as well as those working on social determinants of health and health disparities. Hopefully, this can lead to better anticipation and societal resilience, especially for those populations at greatest risk, for environmental and climate-related shocks in the future.”
COVID-19 is a serious threat and continues to be a major focus of concern, but the global environmental health community also recognizes the persistent environmental threats which will still remain beyond the current pandemic. As several outlets have noted, the current health crisis calls attention to the longer-term issue of whether climate and other global environmental changes may raise the risk of infectious disease emergence or re-emergence and future pandemics. NIEHS is actively working to respond to the COVID-19 crisis and, at the same time, use these circumstances to better understand how environmental threats interact with global health security and how the world can recover from the COVID-19 crisis in ways that enhance global environmental health.
Sajadi MM, Habibzadeh P, Vintzileos A, Shokouhi S, Miralles-Wilhelm F, Amoroso A. 2020. Temperature, humidity and latitude analysis to predict potential spread and seasonality for COVID-19. SSRN Electronic Journal. 10.2139/ssrn.3550308.
Wu Y, Jing W, Liu J, Ma Q, Yuan J, Wang Y, Du M, Liu M. Effects of temperature and humidity on the daily new cases and new deaths of COVID-19 in 166 countries. Sci Total Environ. 2020;729:139051. doi:10.1016/j.scitotenv.2020.139051.