Human-induced climate change is contributing to the length and intensity of wildfire season, as stronger heatwaves, drought, and dry ground cover all create ready fuel in forest and brush lands (1)(2).With wildfire comes smoke, increasing the risk of health problems for everyone everywhere.

Longer, stronger wildfire seasons trend

Extreme wildfire trends are being witnessed globally.

Major fire events were widespread across Europe in July and August 2022, hitting France, Portugal, and Spain hardest due to an extreme heatwave (3). The European Forest Fire Information System (EFFIS) found that there were more detected European fires between June and mid-August 2022 than the long-term average of 2006 to 2021. The number of fires was also higher than the previous highest values recorded since the start of EFFIS data keeping in 2006.

Australia experienced its worst brushfire season in history from July 2019 until March 2020 – 47 million acres burned and nearly 3 billion animals were impacted by the blazes (4). While Australia’s following brushfire seasons haven’t been as severe, it’s expected that grassfires will be “supercharged” by extremely dry conditions preceding the 2023 to 2024 brushfire season (5).

North America witnessed a record-breaking number of wildfires in 2022, as noted in the World Air Quality Report. There were massive, long-lived wildfires reported in Alberta, British Columbia, the Yukon, Alaska, and New Mexico (6).

The overall trend in North America has been towards extreme wildfires and, in some regions, is likely to continue in parts of the continent in 2023. According to the U.S. National Interagency Fire Center, there is significant wildfire potential in western Alaska, the Southwest, the Mid-Atlantic, and Florida (7).

Besides the harmful direct impacts of an active wildfire, there are important health implications that come with vast plumes of smoke impacting communities thousands of miles beyond their source.

Wildfire smoke’s long reach

Wildfire smoke doesn’t just harm air quality near the source. Residents of Washington D.C., Boston, Philadelphia, and New York City were surprised to find their skies turn orange or brown and the sun a strange reddish color in late July 2021, as haze from western wildfires drifted eastward (8)(9).

With the haze came air quality alerts issued from Minnesota to eastern coastal states. Poor air quality has persisted into August, as the recorded air quality index for American and Canadian cities ranged from “moderate” (51 to 100) to “unhealthy” (151 to 200). In the Pacific Northwest, western Canada, Nevada, and California air quality measured “very unhealthy (201 to 300) to as high as “hazardous” (301 and higher).

While no amount of air pollution is safe, “moderate” air quality poses a serious health threat to sensitive members of the public. Increasingly adverse health effects can be felt by the general public as poor air quality measurements rise.

Pictured: Wildfires severely degraded air quality in the western United States and Canada on Tuesday, 3 August, 2021, with some sensors reporting hazardous air quality. Source: IQAir.

Wildfire smoke doesn’t respect seemingly great distances, political boundaries, or even oceans. Smoke from the 2020 western U.S. wildfires was detected in the atmosphere over Finland and Russia (10).

The United Nations World Meteorological Organization reported that smoke from Australia’s brushfires affected New Zealand, Chile, and Argentina in January, 2020 (11).

What’s in wildfire smoke

Wildfire smoke is made up of many elements such as gases and water vapor, but the chief among them is particulate matter (PM), including PM2.5 – particulates measuring 2.5 micrometers in diameter or less – and ultrafine particles (UFPs). Airborne particulate pollutants are the primary health hazard found in smoke.

Airborne pollutants found in wildfire smoke include:

• ultrafine particles
• PM2.5
• PM10
• carbon dioxide
• carbon monoxide
• nitrogen oxides
• volatile organic compounds (VOCs)

UFPs – particulate matter smaller than .01 micron in diameter – is the most dangerous airborne pollutant due to its small size. When inhaled, UFPs easily cross over from the lungs into the bloodstream and all other regions of the body.

Wildfire smoke health effects

Smoke can affect the human body in several adverse ways.

Health problems caused by wildfire smoke exposure can include:(12)(13)

• burning and irritated eyes
• congestion and runny nose
• scratchy throat
• headache
• shortness of breath
• aggravated asthma, COPD, bronchitis, and allergy symptoms
• worsened chronic heart and lung disease
• increased hospitalizations for respiratory illness

People with allergies and asthma are likely to experience more severe symptoms than the general public because their airways are chronically inflamed. Those individuals will find low level exposure to smoke likely to trigger symptoms.

The takeaway

Wildfire smoke will likely continue to pose a serious health threat in the years ahead. However, there are steps that can be taken to manage exposure to wildfire smoke pollution.

• Monitor air quality in real time to know how severely wildfire smoke is impacting the community.
• Avoid going outdoors when air quality is poor and the air is hazy.
• Close doors and windows to keep smoke from getting indoors.
• Use an air purifier for wildfire smoke to help filter outdoor smoke particles as they enter buildings.
• If you must go outdoors during wildfire events, wear an air pollution mask outdoors. Heart or lung damage can occur after even brief exposure to smoke.