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Wildfires, Covid-19, And Climate Change: A Recipe For Disaster

By Parisa Foroutan, Public Health Analyst, Jean Felipe Teotonio, Public Health Chief, and Ajay K Gupta, Co-Founder & CEO,

It is without a doubt that wildfires have increased in frequency and severity over the years. Compared to previous years, wildfires are more than twice as frequent and four times the size.[8] A wildfire is defined as unplanned fires that are caused by “lightning, human activity, and escaped fires from prescribed burn projects”.[2] Since 1983, there has been an average of 70,000 wildfires a year in the United States, burning 7 million acres in the process.[2] For individuals living in wildfire prone areas, this has played a crucial role in their overall health. According to multiple studies, climate change is the main culprit for the increases in wildfire season length, frequency, and burned area.[2] Since 2017, the earth’s surface has increased 0.9°C compared to the 1950s.[10] This increase in temperature has created warmer springs and longer and drier summers, which creates drought and dry soil and vegetation - the perfect recipe for a wildfire.

When thinking about wildfire effects, many often solely think about their direct effects on people and the environment, partially including the loss of vegetation, water quality, habitats for land and aquatic life, loss of homes, and injuries to residents and first responders. The indirect effects of wildfires are not often discussed. The release into the air of toxic contaminants like carbon monoxide, nitrogen dioxide, ozone, fine particulate matter (PM2.5), which are microscopic particles of solid or liquid matter in the air, polycyclic aromatic hydrocarbons (PAH’s), and volatile organic compounds (VOC’s, organic compounds that have a high vapor pressure at room temperature) have been associated with poor health outcomes.[13]

Figure 1: Relative risk (RR) and 95% confidence intervals for emergency department visits for all cardiovascular and respiratory outcomes relative to smoke free days, at lag 0 days, stratified by age.[13]

The respiratory health effects from wildfire smoke exposure can exacerbate and lead to chronic obstructive pulmonary disease (COPD), acute bronchitis, pneumonia, and worsening of asthma.[10] Prolonged exposure to wildfire smoke was found to have an effect on the cardiovascular system triggering heart attacks and stroke, leading to premature mortality.[7] Wildfires can also have damaging effects on one’s mental health. The loss of shelter and personal property takes a tremendous toll on mental health creating increases in PTSD, anxiety, and depression.[12]

Perhaps one of the most interesting and unexpected public health effects from wildfires is the role of wildfires and COVID-19. A respiratory illness caused by the SARS CoV-2 virus, COVID is spread via respiratory droplets and directly infects the cells of the upper and lower respiratory tract impacting lung function.[1] Individuals with pre-existing conditions are at increased risk of infection and complications of the disease.[14] As we have seen from the past three years, COVID is not a one-size-fits-all disease. While the majority of healthy individuals who contract the virus recover, there are a significant number of people who experience complications, long-term effects, and suffer worse outcomes.

Studies have linked COVID severity and susceptibility to wildfire smoke exposure. In wildfire prone areas, at-risk individuals are disproportionately affected by wildfire exposure.

The smoke from wildfires releases a significant amount of PM2.5 and many other contaminants into the air and especially during peak wildfire season. With each increasing amount of 10 micrograms per cubic meter of PM2.5, studies found a 6% increase in asthma-related hospitalizations.[5] When the lungs are exposed to pollutants like PM2.5, these tiny particles can penetrate the skin’s barriers making their way to the lungs and even the bloodstream.[6] This can then irritate the lungs causing inflammation, difficulty breathing, and impaired immune function.[6] With this in mind, those with already compromised lung function are at severe risk of respiratory distress during peak wildfire season, leaving them susceptible to complications from COVID-19.[15] During the 2020 wildfire season, there was a 57% increase in COVID cases in California likely due to impaired lung defenses and increased lung irritation.[4] Interestingly, evidence from a recent study discovered that this was attributed to SARS-CoV-2 RNA being on the surface of outdoor PM2.5, indicating the possibility that PM2.5 can potentially act as a transport vector for viruses by creating a microenvironment conducive to viral persistence.[3],[13] The overlap of wildfires and Covid-19 is a deadly if unexpected combination. The significant increase in cases during peak wildfire season also resulted in a higher number of deaths.

Hospitals during the beginning of the pandemic were hit hard, and given COVID was a novel disease, it was impossible to predict the unimaginable challenges it would cause. Medical equipment, hospital beds, and medications were heavily limited due to the influx of patients. While COVID vaccines have been available to the public since 2021, surges in cases continue to occur. Currently, the dominant variants are EG.5 and FL.1.5.1.[9] As of August 2023, there has been a 14.3% upward trend in hospitalizations due to Covid-19.[9] When combined with communities affected by wildfires, any surge in infectious disease spread can be a recipe for disaster given resources are already taxed.

Through researching key indicators, the most vulnerable and at-risk individuals to develop poor health outcomes from wildfires closely align with those at risk for severe disease from COVID: those with respiratory and cardiovascular conditions. In addition, one’s economic status also plays a major role in determining health outcomes. Indicators such as unemployment, being below 150% poverty level, a lack of access to transportation or a vehicle, can increase risk of exposure and prevent access to safety. The end result, unfortunately, is often an increase in mortality among those most vulnerable.

To mitigate health complications from wildfires, we can attempt to prevent their occurrence – especially as human activity is one of the causes. We can also expand and increase ways to prepare for emergency situations. By utilizing GeoAI solutions and various public health models to predict risks, we can identify and help communities that are disproportionately affected to reduce disparities in outcomes. GeoAI approaches provides the ability to foresee and manage wildfires by implementing mathematical models to determine the optimum distribution of hydrants, fire station locations, classify fire regions, and assess fire susceptibility.[11] By assessing risks and susceptibility of wildfires, responders and residents can prepare and execute evacuation plans more effectively and easily.

The Texas Wildfire Risk Assessment Portal (TxWRAP) is an example of GIS technology being an asset to wildfire mitigation.[11] This application provides access to an assessment report with a map and table informing users of a risk and hazard rating that can guide and improve evacuations.

Wildfires, through the fire itself, the air quality effects, and the downstream impacts, and the exacerbation of other illnesses, carry a significant risk of injury and undesirable health outcomes to all exposed. A Wildfire and Smoke Inhalation Risk Index, combining all potential risks, would prove an incredible value add to the tool belt of those seeking to better prepare and better serve communities and populations affected by these disasters. Such an effort across wildfire prone areas in the western United States can help assess risks and mitigate direct and indirect effects, thus improving health outcomes. Geospatial analytics, especially when merged with AI-based techniques, continue opening the doors to better emergency planning as well as more efficient identification of vulnerable populations and communities.


1. Bohn, M. K., Hall, A., Sepiashvili, L., Jung, B., Steele, S., & Adeli, K. (2020). Pathophysiology of COVID-19: Mechanisms Underlying Disease Severity and Progression. Physiology (Bethesda, Md.), 35(5), 288–301.

2. Climate change indicators: Wildfires. (2023). United States Environmental Protection Agency.,Key%20Points,year%20(see%20Figure%201).

3. Comunian, S., Dongo, D., Milani, C., & Palestini, P. (2020). Air Pollution and Covid-19: The Role of Particulate Matter in the Spread and Increase of Covid-19's Morbidity and Mortality. International journal of environmental research and public health, 17(12), 4487.

4. Cortes-Ramirez, J., Micheal, R.N.,Knibbs, L.D., Bambrick, H., Haswell, M.R., & Wraith, D. (2021). The association of wildfire air pollution with COVID-19 incidence in New South Wales, Australia. ElSevier, 809.

5. Henderson, S.B. (2020). The Covid-19 pandemic and wildfire smoke: Potentially concomitant disasters. American Journal of Public Health.

6. How does PM affect human health? (2023). United States Environmental Protection Agency.

7. How wildfires affect our health. (2016).American Lung Association.,and%20strokes%E2%80%94and%20can%20kill

8. Iglesias, V., Balch, J. K., & Travis, W. R. (2022). U.S. fires became larger, more frequent, and more widespread in the 2000s. Science advances, 8(11), eabc0020.

9. Katella, K. (2023). What to know about EG.5 (Eris)-the latest Coronavirus strain. Yale Medicine.

10. Rossiello, M.R., & Szema, A. (2019). Health effects of climate change-induced wildfires and heatwaves. Cureus 11(5): e4771. DOI 10.7759/cureus.4771

11. Stripling C. & Ballard, L. (2018). How Texas is Using Geospatial Technologies to Mitigate Forest Fires. GIS Lounge.

12. To, P., Eboreime, E., & Agyapong, V. I. O. (2021). The Impact of Wildfires on Mental Health: A Scoping Review. Behavioral sciences (Basel, Switzerland), 11(9), 126.

13. Wildfires.( 2023). World Health Organization.

14. Wildfire smoke and Covid-19.(2020). UC Berkeley.

15. Yu, S. & Hsueh, L. (2022). Do wildfires exacerbate COVID-19 infections and deaths in vulnerable communities? Evidence from California. Journal of Environmental Management, 328,116918.

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