Wildfire Pollution and Immune Health

Wildfire Pollution and Immune Health

Since mid-August, a record-breaking number of wildfires have erupted throughout the West Coast and many continue to burn, with devastating consequences. Over 5 million acres of land have been burned so far, thousands of homes have been destroyed, and over 30 lives have been lost. While wildfires are nothing new, increasingly severe wildfire events have been occurring on a global scale.

In 2019-2020, Australia recorded its worst bushfire season on record, burning at rates never seen before. Though there are many factors that contribute to wildfires, climate change is a key driver that cannot be ignored. Higher temperatures, earlier snow melt, increased droughts and unusual rain patterns due to the changing climate all combine together to form the perfect conditions for fires of unprecedented scale and intensity.

One of the many alarming consequences of the increasing wildfires is far-spreading and long-lasting smoke pollution. Warnings of “hazardous” or “very unhealthy” air quality were in place from California to Washington State, with the air quality in many parts of Oregon ranking among the worst in the world. While the wildfires themselves have been concentrated on the West Coast, the resultant smoke has made its way to the East Coast and even Europe. This year, “very unhealthy” air quality ratings lasted for an average of 4.1 days, which is double the average over the previous decade, with more counties experiencing 8+ days of “very unhealthy” air quality. Worst of all, new wildfires are still continuing to appear.


How Does Wildfire Smoke Impact Our Health?

Wildfire smoke contains a mixture of carbon monoxide (CO), particulate matter (PM), and volatile chemicals. These components differ based on the components feeding the fire. For example, fires that burn through cities tend to release more toxic compounds due to burning plastics, paint, and consumer products that contain more chemicals compared to forest fires or rural fires which are more limited to burning organic matter such as vegetation and wood.

Currently, the U.S. Air Quality Index (AQI) used to report daily air quality levels and associated health risks measures five major pollutants: CO, PM, ground-level ozone, sulfur dioxide, and nitrogen dioxide. It is divided into 6 color-coded categories in which each category corresponds to a different level of health concern. (Please refer to the AQI Basics for further detail).

However, 90% of total particle mass emitted from wildfires comprises fine particulate matter, or particles 2.5 microns or smaller in size (PM2.5), which poses the biggest threat to our health. Due to their small size, PM2.5 can penetrate deep into the lungs, with smaller particles passing through the lungs and into the bloodstream, ultimately settling into and impacting various body tissues. Once PM2.5 penetrates this deeply, the body is unable to filter it out, which creates long-lasting inflammation within the body.

Short-term effects of PM2.5 may include irritation of the eyes, nose, throat, and/or lungs, coughing, shortness of breath, and worsening of pre-existing respiratory or cardiovascular diseases. Meanwhile, exposure to PM2.5 during wildfire events was associated with increased ambulatory dispatches after just one hour of exposure.

While the long-term health effects of wildfire smoke are currently unknown, a recent study followed community residents living in Seeley Lake during the 2017 summer fires which lasted for 49 days, 39 of which exposed residents to EPA-designated “very unhealthy” and “hazardous” levels of PM2.5. Researchers found that after one year of post-wildfire exposure, lung function significantly decreased among the study participants, with more than double reporting lung function below normal thresholds. Lung function remained low even two years after the wildfires had occurred.

Despite limited research on long-term PM2.5 exposure from wildfire events, the long-term health effects due to ambient PM2.5 has been well established and is associated with cardiovascular disease, respiratory illnesses such as asthma and lung cancer, diabetes, premature death among individuals with heart or lung disease, as well as premature births and low birthweight babies.


Covid-19 and Smoke Pollution

As the Covid-19 pandemic continues, wildfire events will continue to overlap and potentially create a “double whammy.” PM exposure may result in weakened pulmonary immunity and thus compromise the ability of our bodies to respond to respiratory viruses such as the influenza virus or SARS-CoV-2 (which causes Covid-19). One study found that the effects of smoke on the immune system may last for months, as exposure to higher levels of PM2.5 during the wildfire seasons has been associated with a more severe flu season the following winter. Thus, wildfire smoke exposure may also increase the risk of contracting Covid-19 and/or increase the severity of disease among those already infected.

This effect can also be seen in reverse. People who currently have or are recovering from Covid-19 may be at higher risk of health effects from wildfire smoke exposure due to compromised heart and lung function resulting from Covid-19. It is also important to note that other at-risk groups for wildfire smoke largely overlap with those who are at-risk for Covid-19, such as adults 65 or older, pregnant women, those with chronic health conditions (e.g., asthma, diabetes, heart and lung disease), immuno-compromised individuals, and those who are of a lower socio-economic status.


What Can We Do?

While it is not possible, nor ecologically appropriate, to eradicate all wildfires – there are measures that we can take to mitigate our smoke exposure, as well as help reduce climate change and/or human behavior-driven wildfire events.

Precautions During Wildfire Events

  • Check the Air Quality Index in your area to see whether you need to limit your time outdoors on a given day.
  • Listen to advisories: if you are told to stay indoors or if the air looks smokey outside, stay indoors whenever possible.
  • If you are in a car, keep your windows and vents closed. If you are using the air conditioner, change the setting to “recirculate” mode.
  • While cloth masks help to prevent the spread of Covid-19, they do not protect against smoke exposure. For individuals who must spend time outdoors, consider wearing a fit-tested and approved N95 or P100 respirator to help reduce your exposure (however, note that these respirators may be in shorter supply due to the pandemic). Avoid N95 respirators with exhalation valves, as they may promote the transmission of Covid-19.

Improving Air Quality at Home

  • If the outdoor air quality is poor, keep windows and doors closed. When using the AC, keep the fresh air intake closed to prevent infiltration of outdoor smoke. If you are not able to turn off the fresh air intake, make sure the filter on the fresh air intake is clean.
  • Use an air filter and/or portable air cleaner capable of high particle removal efficiency.
  • Integrate air purifying plants to naturally improve air quality indoors. The presence of plants may also help reduce stress during these times.
  • Reduce indoor air pollution by limiting combustion activities such as lighting candles and fireplaces, smoking, or using gas stoves without functioning kitchen hoods. Particles may be resuspended by daily activities such as walking or vacuuming. If possible, use a vacuum with a High Efficiency Particulate Air (HEPA) filter or wear a mask when using a traditional vacuum.

Help Combat Climate Change

  • Switch to eco-friendly modes of transportation. Vehicles are one of the main sources of PM pollution. Use public transportation or bike when possible. If you rely on your own vehicle, consider switching to a hybrid or electric car to reduce PM emissions.
  • Plant more trees. Trees help to remove carbon dioxide from the air and help to combat climate change.
    Lower your own environmental impact. There are many small changes you can incorporate into your life to reduce your carbon footprint and live a more sustainable life. Simple examples include bringing your own bags to the grocery store and using reusable water bottles.
  • Prevent human-caused wildfires. Did you know that nearly 85% of wildfires are caused by humans? If you live near or are visiting a wildfire prone area (e.g., national parks or forests), follow these tips to avoid starting a wildfire.