E2A: Wildfire Smoke

Breathe Easy: Protecting Ourselves from Wildfire Smoke

Educational Tools and Posters for You and Your Clinic

Click on any thumbnails below or right-click ‘save as’ to download the educational material.

Bottom Line

Wildfire smoke is an increasingly important public health concern in Canada and around the world.
In Alberta, large wildfire events have significantly affected communities through poor air quality and prolonged smoke exposure. Evidence shows that wildfire smoke exposure increases respiratory symptoms, emergency department visits, hospitalizations, cardiovascular illness, and all-cause mortality.
As wildfire seasons become more frequent and severe, proactive preparation, patient education, and smoke-exposure reduction strategies are becoming increasingly important to help protect our health and support vulnerable populations.

Evidence

Current evidence shows that wildfire smoke exposure is associated with increased respiratory symptoms, worsening of chronic respiratory disease (particularly asthma and COPD), cardiovascular illness, emergency department visits, hospitalizations, and all-cause mortality. Evidence is strongest for short-term respiratory effects, while growing evidence suggests cardiovascular, reproductive, and longer-term health impacts may persist for weeks to months following major smoke events. Importantly, health effects may occur even at relatively low levels of smoke pollutant called Particulate Matter 2.5 (PM2.5) and may not increase linearly, meaning smaller increases at lower concentrations can still have clinically meaningful impacts.

A 2024 meta-analysis found that for every 1 µg/m³ increase in wildfire-specific PM2.5, there is:¹

All-cause mortality increased by 0.15%
Respiratory hospitalizations increased by 0.25%
Respiratory emergency department visits increased by 0.36%

Although these percentage increases may appear small, wildfire smoke events often involve much larger PM2.5 increases over several days, potentially resulting in substantial population-level impacts, particularly among higher-risk individuals and communities.

Canadian evidence further supports these findings. A British Columbia population-based study (2003–2010) found that every 10 µg/m³ increase in PM2.5 during wildfire season was associated with a 6% increase in salbutamol dispensations, reflecting worsening respiratory symptoms and asthma exacerbations. On severe smoke days, this increased to approximately 7%.²

Emerging evidence also suggests wildfire smoke may have persistent effects beyond the immediate smoke event. A large U.S. multi-state study reported increased risks of ischemic heart disease, arrhythmia, hypertension, pneumonia, asthma, and COPD that persisted for up to three months after wildfire exposure.³ Alberta-specific studies following the 2016 Fort McMurray wildfire also demonstrated ongoing respiratory and mental health impacts months after the event, particularly among evacuees, firefighters, and first responders.⁴ ⁵

Can Reducing Exposure Reduce Harm?

Although randomized trials are limited, evidence suggests that reducing wildfire smoke exposure can meaningfully reduce health risks. Rapid reviews and public health guidance support:⁶ ⁷ ⁸

Portable HEPA air cleaners, which can substantially reduce indoor PM2.5 concentrations
Cleaner indoor air spaces (e.g., libraries, recreation centres, filtered indoor environments)
Well-fitting respirators (N95/KN95) during unavoidable outdoor exposure
Air Quality Health Index (AQHI)-guided activity modification, particularly for higher-risk individuals

While more real-world effectiveness studies are still needed, current evidence strongly supports taking proactive measures to reduce exposure, particularly for people with asthma, COPD, cardiovascular disease, pregnancy, older age, or other vulnerabilities.

Eight Steps to Prepare for Wildfire Smoke in Your Community

Prepare Yourself (For patients and healthcare providers)

Here are practical steps to help you feel more prepared and better navigate wildfire smoke events.

1. Monitor air quality in real time

Download the WeatherCAN App for real-time air quality data based on the Canadian Air Quality Health Index (AQHI) and set notifications for dangerous levels.
Developed by Environment and Climate Change Canada (ECCC), WeatherCAN is Canada’s official weather application and a reliable source for weather and air quality information.

The app provides:

Real-time Air Quality Health Index (AQHI) data for your local community
Forecasts for over 10,000 locations across Canada
Health recommendations based on current air quality conditions
Once downloaded:
Set your location to receive AQHI information for your community (this can be updated anytime)
Turn on notifications and customize alerts based on AQHI thresholds that matter to you
Receive timely alerts when air quality reaches higher-risk levels, helping you make informed decisions to reduce exposure during wildfire smoke events

You may also use the IQAir app for additional air-quality information by clicking on this link here.

2. Use a portable air cleaner (PAC) with a HEPA filter

Portable air cleaners with HEPA filters can help reduce wildfire smoke particles indoors and work best when doors and windows are closed.

3. Prepare for wildfire smoke events

Have an emergency plan in place before smoke levels rise, especially if you are at higher risk (e.g., individuals with asthma or COPD, older adults, pregnant individuals, children, outdoor workers, or people with underlying health conditions). If you are a patient, your healthcare provider can help you create an emergency plan!
Identify backup locations with cleaner air (e.g., libraries, recreation centres, schools, friends’ or relatives’ homes with HEPA filtration or air conditioning)
Prepare emergency supplies, including medications you may need

4. Understand wildfire smoke and its health impacts

Learn more about:

a. Air Quality Health Index (AQHI) Basics
b. Wildfire Smoke Composition
c. Effects of Wildfire Smoke on Health

(All explained in detail in the deeper dive section below)

Prepare Your Patients and Your Clinic (For healthcare providers and clinic teams)

1. Prepare Your Clinic Environment

Display Air Quality Health Index (AQHI) information in waiting rooms (e.g., WeatherCAN on clinic TVs or screens)
Consider using portable air cleaners with HEPA filters in clinic spaces to help reduce smoke particles indoors
Become familiar with local “safe-air” spaces (e.g., libraries, recreation centres, and community facilities) where patients may be able to access cleaner air during wildfire smoke events

2. Identify Patients at Higher Risk

Use a climate-health lens when taking patient histories and identifying wildfire smoke-related risk factors (see the document “Using a Climate Health Lens in Patient Histories” in the Educational Tools section at the top).

Patients at higher risk may include:

Individuals with asthma, COPD, cardiovascular disease, diabetes
Older adults
Children & adolescents
Pregnant individuals
Immunocompromised individuals
Outdoor workers
First responders
Indigenous and remote communities

3. Support Patient Preparedness Through Action Plans

Complete an asthma action plan for high-risk patients before wildfire smoke events occur. Consider discussing ways to reduce smoke exposure, medications that should be readily available, and symptoms that may require medical attention.

Researchers in Washington State have developed a dedicated “Wildfire Smoke Action Plan for Children with Asthma”. It combines traditional asthma management with wildfire-specific actions. It is available here.

Also support all at risk patients in creating a more comprehensive emergency plan for severe smoke and wildfire risk (or other disasters), including the possibility of having to leave your home. The Government of Canada has an excellent tool to help you create your home emergency plan, you can access it by clicking here.

The City of Calgary also has an excellent preparedness website – preparing your business and household for emergencies: Get Prepared for Emergencies.

4. Contribute to Air-Quality Monitoring

Consider implementing an air monitor at your clinic. You can contribute to local and global air-quality monitoring efforts by hosting a personal, low-cost sensor and linking it to a public network such as IQAir’s Air Quality Community.

Why Does It Matter?

The Growing Impact of Wildfires in Canada

In 2023, Calgary experienced its highest recorded level of wildfire smoke, with 512 hours of smoke observed at the Calgary Airport (Government of Canada).

Although often considered a “natural” disaster, wildfires in Canada are occurring with greater frequency, intensity, and duration due to climate-related changes, including rising temperatures, drier conditions, prolonged drought, and increased lightning activity. These changes are contributing to larger and more severe wildfire seasons.⁹

Why Wildfire Smoke is Dangerous

Wildfire smoke contains a mixture of harmful pollutants, including fine particulate matter (PM2.5) which is the primary pollutant of concern. PM2.5 particles are small enough to travel deep into the lungs and enter the bloodstream, contributing to both short and long-term health effects. Research suggests wildfire-related PM2.5 may be up to 10 times more harmful than particulate matter from other pollution sources.¹⁰
¹¹

Health Impacts of Wildfire Smoke

Exposure to wildfire smoke has been associated with:¹ ¹⁰

Increased respiratory symptoms and worsening of conditions such as asthma and COPD
Increased cardiovascular and respiratory illness
More emergency department visits, clinic visits, and hospitalizations
Increased all-cause mortality
Pregnancy-related complications (this will be discussed in more details in the Wildfire Smoke & Pregnancy campaign)
Missed school and activities due to worsening respiratory symptoms, particularly among children

Mental Health Impacts of Wildfires

In addition to physical health effects, direct exposure to wildfire events may be associated with:

Post-traumatic stress disorder (PTSD)
Anxiety
Depression

Patients often describe wildfire experiences as distressing, disruptive, and difficult to forget.9,12

Why Preparation Matters

Wildfire smoke is often treated as a short-term event; however, its impacts can persist long after visible smoke clears. As wildfire seasons continue to intensify, preparing patients, communities, and healthcare systems is becoming increasingly important. While important knowledge gaps remain, current evidence highlights the need for proactive planning to reduce exposure and protect health.¹³

Scripts

Consider the following scripts to use with patients who are climate aware and one script (#4) to use for patients who you may feel may benefit from understanding the link between the climate change and increasing wildfires.

We're seeing more wildfire smoke these days, and it can affect your health. A few simple steps can help protect you and your family. Before you leave, please take a look at this poster for tips on staying safe during smoky days."

Wildfire smoke is becoming more common and can affect your breathing, heart, and overall health. Having a plan for smoky days can help keep you safe. Before you leave today, please take a look at this poster for simple tips to reduce smoke exposure."

Because wildfire smoke can affect your health more than most people, I’d like us to make a quick plan for smoky days. That way, you’ll know exactly what to do if air quality gets worse.

Let’s go over a few simple things—when to stay indoors, how to reduce smoke exposure, what symptoms to watch for, and when to use medications or seek care.”

Wildfire smoke can affect your breathing, heart, and overall health. Scientists have found that climate change, driven mainly by burning fossil fuels, is increasing the risk of wildfires. Having a plan for smoky days can help protect your health.

Before you leave, please take a look at this poster for simple ways to reduce smoke exposure and stay safe."

Deeper Dive:

The following three topics will be discussed below:

Air Quality Health Index (AQHI) Basics – How to use the index to improve health
Wildfire Smoke Composition
Effects of Wildfire Smoke on Health

AQHI- How to use the index to improve health

What is the Air Quality Health Index (AQHI)?

The AQHI represents the relative risk of the main air pollutants on human health, most notably PM2.5, in real-time. It ranges from a scale of 1 (LOW) to 10+ (VERY HIGH) and provides information to help guide exposure levels on an individual and community basis.

Why is the AQHI Important?

Air quality cannot always be judged by what you see or smell. During wildfire events, smoke may increase health risks even when the air does not appear visibly smoky. Checking the AQHI can help guide decisions about outdoor activities and when to take steps to reduce smoke exposure — particularly for people at higher risk, such as children, older adults, pregnant individuals, outdoor workers, and those with asthma or COPD.

The AQHI comes along with corresponding health advice on how and when to mitigate your exposure.

The infographic below summarizes recommended activity modifications according to AQHI levels and highlights differences between the general population and individuals at higher risk of health impacts.

Access this visual graphic on AT-RISK vs. GENERAL population by clicking the poster above. Sourced from AQHI – Activity Guide (Alberta Air Shed)

You can also find additional guidance on interpreting AQHI values and planning outdoor activities through the BCCDC Outdoor Events AQHI guide.

Wildfire Smoke Composition: A Unique Type of Air Pollution

Wildfire smoke is not the same as typical outdoor air pollution. Its composition can vary depending on what is burning, weather conditions, and where the smoke travels. As smoke moves through communities, it may pick up additional pollutants from urban environments, including emissions from vehicles, industrial areas, infrastructure, and contaminated soil.
Unlike many forms of air pollution, wildfire smoke can travel long distances, affecting air quality hundreds to thousands of kilometres away for days or even weeks after a wildfire begins. It may also temporarily alter the composition and concentration of background air pollutants, particularly fine particulate matter (PM2.5).¹ ¹⁰

Suggested Reading: Hidden Dangers of Urban Wildfire Smoke

What is Wildfire Smoke Made Of?

Wildfire smoke is a complex mixture of gases and particles, some of which may become more harmful through chemical reactions in the atmosphere.

Common components include:

Fine particulate matter (PM2.5): the primary pollutant of concern and the most studied component of wildfire smoke
Carbon monoxide (CO)
Nitrogen dioxide (NO₂)
Ozone (O₃) (formed secondarily through atmospheric reactions)
Volatile organic compounds (VOCs) and other gases
Toxic substances, including heavy metals and polycyclic aromatic hydrocarbons (PAHs)

For example, during the 2018 Camp Fire in Northern California, wildfire smoke contained elevated levels of contaminants from burned buildings and soil, including lead, with concentrations reported to be 50 times higher than the average air levels.¹²

What is PM2.5?

Particulate Matter 2.5 (PM2.5) refers to tiny particles in the air measuring 2.5 micrometres or smaller in diameter (≤2.5 μm). These particles are too small to see with the naked eye and may contain chemicals, toxins, metals, and other harmful substances.

To put this into perspective, PM2.5 particles are approximately 30 times smaller than the width of a human hair.

Because of their small size, PM2.5 particles can:

Remain suspended in the air for long periods of time
Travel deep into the lungs
Enter the bloodstream and affect multiple organ systems

For this reason, PM2.5 is considered the pollutant posing the greatest health concern during wildfire smoke events.⁷
Learn More: What is PM2.5? (IQAir)

Common Sources of PM2.5:

PM2.5 can come from many sources, including:

Wildfire smoke, smoke, and soot from burning materials
Vehicle emissions and fuel combustion
Power plants and industrial processes
Chemical reactions between pollutants in the atmosphere (e.g., sulfur dioxide, nitrogen oxides, and volatile organic compounds)

PM2.5 Exposure: What Levels Are Considered Safe?

The World Health Organization (WHO) 2021 Air Quality Guidelines recommend that annual average PM2.5 exposure should not exceed 5 μg/m³, as even low levels of exposure may affect health.¹¹

In Calgary, the average ambient PM2.5 concentration in 2024 was approximately 5 μg/m³. However, during wildfire season, PM2.5 concentrations can rise dramatically, with short-term spikes exceeding 90 μg/m³ in a single hour, and peak daily readings reaching substantially higher levels.¹⁴

Suggested Reading:2025 Alberta Airshed Report

Why PM2.5 May Be Harmful Even at Lower Levels: Surprising Facts!

Surprisingly, the relationship between PM2.5 exposure and health impacts is not always linear. Research suggests that even small increases in PM2.5 at lower concentrations may lead to meaningful increases in health risks, particularly for respiratory outcomes.¹⁵

Rather than health risks increasing proportionally at all exposure levels, some studies suggest the greatest increase in harm may occur at lower-to-moderate concentrations, before it begins to plateau at higher concentrations.

For example, a study by the BC Centre for Disease Control (BCCDC) found that emergency department visits for acute respiratory symptoms increased as PM2.5 levels rose during wildfire smoke events, particularly at lower exposure ranges.

Even when air quality does not appear visibly poor, wildfire smoke may still affect health. This highlights the importance of monitoring tools such as the Air Quality Health Index (AQHI) and taking protective measures early especially for individuals at higher risk.

Key Takeaway: Humans may be more vulnerable to the short and long-term effects of PM2.5 than expected, and health effects can occur even at relatively low levels of exposure.¹⁶

Read this article: The Public Health Paradox of Wildfire Smoke

Additional Information on Other Wildfire Smoke Pollutants:

Polycyclic Aromatic Hydrocarbons (PAHs): PAHs are a group of chemicals formed when materials such as wood, oil, coal, gas, or tobacco burn incompletely. Some PAHs, including benzo[a]pyrene, are known carcinogens and may contribute to adverse health effects.
Nitrogen Dioxide (NO₂): Nitrogen dioxide (NO₂) is a reddish-brown gas with a pungent irritating odour that can irritate the lungs and worsen respiratory symptoms. It contributes to ground-level ozone formation, acid rain, and has been linked to respiratory disease.
Ozone (O₃): Produced through chemical reactions of non-natural sources creating the secondary pollutant of ozone. It can travel long distances and contribute to large-scale air pollution events, particularly during hot weather and wildfire seasons.

Effects of Wildfire Smoke on Health: What Studies Show

Wildfire smoke is a complex mixture of fine particulate matter (especially PM2.5), gases, and organic compounds. The evidence base consistently links smoke exposure with acute respiratory morbidity and all-cause mortality, with growing evidence for cardiovascular impacts and medium-term effects lasting weeks to months after smoke events.

Below are key, policy relevant, peer-reviewed findings, followed by Alberta-specific evidence, evidence gaps and references.

Key, peer reviewed, findings:

Global/Canada 2023 wildfires (Nature 2025) estimated around 5,400 acute deaths in U.S. and Canada combined from short-term smoke spikes and around 82,100 additional premature deaths globally due to chronic exposure.¹⁷
Cost-effectiveness and analysis projects prevention of around 4,418 corticosteroid treated exacerbations, 643 emergency department (ED) visits, and 425 hospitalizations over 5 years; government rebates up to two thirds of device cost generally cost-effective.⁶

Alberta specific evidence:

Research from Alberta highlights both the short and longer-term health impacts of wildfire smoke exposure and wildfire-related events.

Approximately 102 days after the 2016 Fort McMurray wildfire, 10.1% of evacuees and workers reported a fire-related health condition, most commonly mental health concerns and respiratory symptoms.¹⁸
A cohort study of 1,234 firefighters using Alberta administrative health data found firefighters exposed to the wildfire had 2.56 times greater odds of developing new-onset asthma compared with matched controls (OR 2.56, 95% CI: 1.75–3.74). Persistent lung changes were also observed during follow-up.⁴
Short-term exposure during the 2016 Horse River wildfire was associated with reduced small airway function among first responders, particularly within the first three months following deployment.¹³
Environmental monitoring and public health assessments evaluated air and soil quality in Fort McMurray and surrounding communities, comparing findings with established human health guidelines.¹⁹
Provincial reports have documented significant PM2.5 increases during wildfire smoke events, highlighting important implications for air quality management and public health planning.²⁰
Alberta experienced one of its most severe wildfire seasons on record, with approximately 3.2 million hectares burned — roughly 15 times the typical annual amount — contributing to widespread smoke exposure and poor air quality across the province.²¹

Evidence gaps:

Although the health impacts of wildfire smoke are increasingly well understood, important knowledge gaps remain. Researchers are still working to better understand:

How different levels of wildfire smoke exposure affect health, particularly at very low and very high concentrations of PM2.5, where health risks may not increase in a predictable way.
The long-term health impacts of repeated wildfire smoke exposure, including potential risks for chronic disease and cancer.
Why some people are more affected than others, including the role of factors such as heat waves, housing quality, socioeconomic conditions, and access to cleaner indoor air.
How effective protective strategies are in real-world settings, including clean-air shelters, portable HEPA filtration, masks, and other interventions aimed at reducing smoke exposure.

Despite these uncertainties, current evidence strongly supports taking steps to reduce wildfire smoke exposure particularly for individuals and communities at higher risk.

Attributions

Webcopy created by Drs. Keiko Patterson, Sonja Wicklum, Clark Svrcek and Jennifer Obeid from the Department of Family Medicine, University of Calgary Cumming School of Medicine, January 2026.

References:

¹Gould CF, Heft-Neal S, Johnson M, Aguilera J, Burke M, Nadeau KC. Health effects of wildfire smoke exposure. Annu Rev Med. 2024;75:277-292. doi:10.1146/annurev-med-052422-020909.↩

²Elliott CT, Henderson SB, Wan V. Time series analysis of fine particulate matter and asthma reliever dispensations in populations affected by forest fires. Environ Health. 2013;12:11. doi:10.1186/1476-069X-12-11.↩

³Wei Y, Castro E, Yin K, et al. Medium-term exposure to wildfire smoke PM2.5 and cardiorespiratory hospitalization risks. Epidemiology. 2025;36(5):606-615. doi:10.1097/EDE.0000000000001881↩

⁴Cherry N, Barrie JR, Beach J, Galarneau JM, Mhonde T. Respiratory outcomes of firefighter exposures in the Fort McMurray fire: a cohort study from Alberta, Canada. J Occup Environ Med. 2021;63(9):775-784. doi:10.1097/JOM.0000000000002288.↩

⁵Belleville G, Ouellet MC, Lebel J, Ghosh S, Morin CM, et al. Psychological Symptoms Among Evacuees From the 2016 Fort McMurray Wildfires: A Population-Based Survey One Year Later. Front Public Health. 2021;9.↩

⁶Adibi A, Barn P, Shellington EM, et al. HEPA filters for preventing wildfire-related asthma complications: a cost-effectiveness study in British Columbia. Am J Respir Crit Care Med. 2024.↩

⁷Health Canada. Human health effects of wildfire smoke. Government of Canada; 2024.↩

⁸National Collaborating Centre for Environmental Health, National Collaborating Centre for Methods and Tools. Rapid review: indoor air filtration during wildfire smoke events. NCCEH; 2025.↩

⁹Polidori A, Papapostolou V, Collier-Oxandale A, Hafner H. Community in Action: A Comprehensive Guidebook on Air Quality Sensors. South Coast Air Quality Management District; 2021. Accessed July 2, 2025. Available from: http://www.aqmd.gov/aq-spec/special-projects/star-grant ↩

¹⁰Basilio E, Chen R, Fernandez AC, Padula AM, Robinson JF, Gaw SL. Wildfire smoke exposure during pregnancy: a review of potential mechanisms of placental toxicity, impact on obstetric outcomes, and strategies to reduce exposure. Int J Environ Res Public Health. 2022;19(21):13727. doi:10.3390/ijerph192113727.↩

¹¹World Health Organization. WHO global air quality guidelines: particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide. World Health Organization; 2021. Available from: https://www.who.int/publications/i/item/9789240034228 ↩

¹²California Air Resources Board. New analysis shows spikes of metal contaminants, including lead, in 2018 Camp Fire wildfire smoke. Accessed July 2, 2025. Available from: https://ww2.arb.ca.gov/news/new-analysis-shows-spikes-metal-contaminants-including-lead-2018-camp-fire-wildfire-smoke ↩

¹³Moitra S, Tabrizi AF, Fathy D, Kamravaei S, Miandashti N, Henderson L, et al. Short-term acute exposure to wildfire smoke and lung function among Royal Canadian Mounted Police officers. Int J Environ Res Public Health. 2021;18(22):11787. doi:10.3390/ijerph182211787.↩

¹⁴Government of Alberta. Air indicators—fine particulate matter. Alberta.ca. Published 2024. Accessed July 2, 2025. Available from: https://www.alberta.ca/air-indicators-fine-particulate-matter ↩

¹⁵Henderson S. The public health paradox of wildfire smoke. British Columbia Medical Journal. Published 2024. Accessed July 2, 2025. Available from: https://bcmj.org/bc-centre-disease-control/public-health-paradox-wildfire-smoke ↩

¹⁶Thangavel P, Park D, Lee YC. Recent insights into particulate matter (PM2.5)-mediated toxicity in humans: an overview. Int J Environ Res Public Health. 2022;19(12):7511. doi:10.3390/ijerph19127511.↩

¹⁷Zhang Q, Wang Y, Xiao Q, Geng G, Davis SJ, Liu X, et al. Long-range PM2.5 pollution and health impacts from the 2023 Canadian wildfires. Nature. 2025;645(8081):672-678. doi:10.1038/s41586-025-09482-1.↩

¹⁸Cherry N, Haynes W, Akhtar S, et al. Effects of the Fort McMurray wildfires on the health of evacuated workers: follow-up of 2 cohorts. CMAJ Open. 2017;5(3):E638-E645. doi:10.9778/cmajo.20170042.↩

¹⁹Alberta Environment and Parks. Horse River Wildfire Response: Environmental Monitoring and Science Division. Government of Alberta; 2018.↩

²⁰Landis MS, Edgerton ES, White EM, Wentworth GR, Sullivan AP, Dillner AM. The impact of the 2016 Fort McMurray Horse River wildfire on ambient air pollution levels in the Athabasca Oil Sands Region, Alberta, Canada. Sci Total Environ. 2018;618:1665-1676. doi:10.1016/j.scitotenv.2017.10.008.↩

²¹Alberta Biodiversity Monitoring Institute. Effects of 2023 Wildfires in Alberta: Supplementary Report. ABMI; 2023.↩