Wildfires and its Effects on Human Health

Photo by Gagaz Adam


Wildfires and climate change are two significant topics among today’s headlines. Often times, the impacts that are seen either first hand or secondary are to the environmental aspect of the hazard. Remaining issues such as economic, safety, humanitarian response, and infrastructure stability to wildfires are often seen following the devastation that comes with the natural hazard. However, there is a highly regarded aspect of this danger that is commonly undervalued. That subject is the impacts of the fires themselves on humanitarian health. Although not the most obvious and apparent hazard, human health continues to suffer annually with increasing quantities of wildfires, as well as strengthening blazes which create another layer of dangers for residents nearby and worldwide. There are several attributes related to the dangers that are presented by these wildfires. A few of these health-related hazards are smoke and their increasing trend of lack of fresh air, ash and debris particles that are ejected from the fire origins to create indirect hazards, and finally water quality that impedes routine activities for the everyday citizen. Some hazards, such as burning eyes and other health concerns based upon smoke as noted below, can be seen easily. However, concentrations within waterways and internal diseases likely won’t be as apparent until damage occurs and medication is required. Each of these items will be discussed at length in respect to their impact on the human body and resources that are required for the body to survive on a daily basis.

Personal Health Problems Associated with Wildfire Particles

Wildfire Smoke & Health Impacts

Wildfire air pollution is one element of these hazards that can be seen on specific satellite images and throughout the horizon. However, there are times when it also is invisible to the human eye and is only notable when health issues arise. These include watery and scratchy eyes, burning of the eyes, raspatory problems, and internal diseases. Although apparent across the sky and on visible satellites, smoke is often detected most commonly throughout the summer months. This is due to the higher frequency of fires during the peak season, sun angle at its maximum, and extended daylight hours that create a larger window of visibility. Stanford labs have estimated an increase of 3.4% of preterm deaths within babies can directly related to wildfire smoke. This increasing trend now accounts for an average of 7,000 deaths annually. Smoke and visible pollution are the most common sources of health problems from wildfires. According to Naveena Bobba, director of public health emergency preparedness and response at the San Fransisco Department of Public Health, “Children are especially susceptible because their respiratory systems are still developing”. Heart and lung disease are two common elements that have been found within children and the elderly.

Impacts and Preventatives of Wildfire Smoke

According to the EPA, the United States averages over 400,000 days of wildfire smoke on an annual basis. Since 2000, the western United States have averaged an increase of nine days of high wildfire and smoke days per year. This now calculates to nearly 55% of a year consecutively with high fire and smoke danger. Each of these events are continuing to assist in an already degrading level based upon increasing CO2 and other elements that have caused warming within the climate. Although several states and cities illustrated below are located across the western states, there are notable eastern cities that have increased significant smoke days in the last decade. Boston, Baltimore, and Philidelphia are situated along the I-95 corridor but have increased in smoke and significant smoke days. With a changing climate and undulating polar jet stream, these days are increasing and can be seen with milky skies and hazy sunsets during the afternoon and evening hours. Smoke from western and Canadian wildfires are being carried farther eastward than ever with increasing amounts of smoke and debris being polluted into the air. These locations are perfect examples of indirect impacts from fires over 500 miles away. Since 2021, 193 medical facilities across the county have treated wildfire smoke related victims, a number in which has never been seen before.

NOAA Data Indicating Increasing Smoke Day Trends

Wildfire Ash & Debris

Although smoke and increasing breathing hazards are rising annually based upon the striking wildfire statistics, burning ash and debris are also problematic for communities that reside close to burn scars of these fires. Falling ash and particles can be a hazard for surface burns to an individual’s skin and clothing when working outdoors or participating in recreational activities. Masks such as p-100 or N95 grades are recommended, similarly, to protect from low air quality and other particles. According to Geology and Human Health, 90% of smoke and ash particles are small enough to be inhaled into the blood stream of an individual. This hazard alone results in 50-80% of all wildfire deaths as of 2019. These ash particles contain a high value of phosphorus, potassium, calcium, and other natural elements that clog soil pours and create dangerous agricultural impacts. This includes the crops grown within rural fields and gardens. Within these regions, crop health may be compromised and not suitable for consumption. While creating a covering, AC and heating units may suffer from lack of airflow due to the accumulation of ash from wildfires. This creates an indoor air quality hazard with filters and overall equipment failing or minimalizing their typical responsibilities. With burning ash particles creating mercury burn off, this can also lower air and water quality. Mercury is sent into the atmosphere or into the subsurface of the Earth creating hazards to the air that is breathed in, as well as growing conditions for agriculture and water resources. Depending on the wet or dry climate as shown below, the impact may vary based upon location and conditions.

Wildfire Ash and Mercury Flow Cycles

Water Quality

Water quality is a primary concern related to wildfires. This hazard can be created during and after the event. However, it is likely to increase in danger following the fire but can be dependent on the size and strength of the wildfire itself. With evidence already published by sources such as CalFire and the EPA, wildfires continue to increase in coverage and intensity since the 1990’s. Each of these worsening seasons will likely result in a more problematic situation related to water quality and quantity. Published in 2020, several studies across California resulted in an average of 67% increase in wildfire concentration contaminants in burned watershed regions, compared to non-burned watershed regions. Although the fire can impact those nearby, water flow is continuous and will impact those that may reside hundreds of miles away. Due to several additional hazards that create the low water quality, the underwater sediment can also be negatively impacted as well. Ash and other toxic debris may be flown from the burn scar itself into the hydrologic location including but not limited to rivers, streams, lakes, ponds, and other local and more widespread water ways. According to the USGS, Colorado spent a near record $26 million dollars during the 2018-2019 wildfire seasons on water quality mitigation tasks based on wildfires alone.

Perdue Research of Air & Water Quality Variability Based Upon Wildfire Debris

With air-borne debris being a concern, debris flows are another concern that lower water quality. Burned vegetation, soil and other items such as structural debris are likely to be washed into the waterway. These items will directly impact the direct oxygen, pH, aquatic species, and other variables that are located within the waterways. According to the EPA, 65% of the western United States’s freshwater resides within forested watersheds. This creates the danger for a lack of clean drinking water. River and stream banks may be susceptible to more significant landslides based upon the slope, aspect, and composition of the land making each tributary’s level of concern specific to its own. Since 2013, the Rim Fire and Camp Fire (2018) were recorded as two of the largest fires every in California history. Each of these events burned some extent of the water and public works structural resources creating a public and private hazard for water usage. Although water treatment plants and other health related infrastructures are responsible for cleaning the important necessity, wildfires only complicate matters more by compounding the natural and anthropogenic issues that those agencies face.


In conclusion, wildfires not only negatively impact the planet as a whole, but also those who reside across its land. Wind driven smoke, polluted hydrologic resources, and raining ash and debris particles create a significant concern for those who live within high fire season locations. These hazards will only enhance previous health concerns to those who own raspatory and other illnesses. Although commonly misunderstood, each of these hazards can spawn hundreds or thousands of miles from the location of the actively burning fire. Outside of the primary fire fighting activates, these hazards can pose the most dangerous risks to those within its path and unrelated health issues.

Looking Ahead

Forging ahead to the final blog of the series, the remaining time will be used as a case study illustration to examine the impact of wildfires on specific wildlife. This will include the distribution of individual animal species, potential migration patters, and mitigation and remediation strategies that are currently being utilized for strengthen the boundaries of these animals lives.

Additional Resources

Wildfire & Human Health Research Gaps


Wildfire Ash Clean Up Hazards


Wildfire Smoke on the Human Body


Burning Biomass and Human Health

Works Cited

Garthwaite, J. (2021, August 23). Wildfire smoke and early births. Stanford News. Retrieved April 5, 2022, from https://news.stanford.edu/2021/08/23/wildfire-smoke-early-births/

Murphy, S. `, & Ebel, B. A. (2019, March 1). Water quality after wildfire active. Water Quality After Wildfire | U.S. Geological Survey. Retrieved April 30, 2022, from https://www.usgs.gov/mission-areas/water-resources/science/water-quality-after-wildfire

Node view. Wildfire: Its Effects on Drinking Water Quality | HealthLink BC. (2021, May 1). Retrieved April 12, 2022, from https://www.healthlinkbc.ca/healthlinkbc-files/wildfire-its-effects-drinking-water-quality

Safe cleanup of Wildfire Ash. Boulder County. (2020, August 20). Retrieved April 29, 2022, from https://www.bouldercounty.org/safety/fire/safe-cleanup-of-wildfire-ash/

World Health Organization. (2022). Wildfires. World Health Organization. Retrieved April 21, 2022, from https://www.who.int/health-topics/wildfires#tab=tab_1

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