Wildfires Impact on Human Health and Safety Tips

Wildfires are no longer rare, seasonal disasters – in many regions they are now a yearly reality, with smoke drifting hundreds or even thousands of kilometres from the flames.

The World Health Organization estimates that the combined effects of outdoor and household air pollution are linked to about 7 million premature deaths every year worldwide, much of it driven by fine particulate matter such as PM2.5 that wildfire smoke can sharply increase. 

Recent research on Canada’s record 2023 wildfire season suggests that smoke from those fires alone contributed to roughly 87,000 premature deaths worldwide, showing how a single extreme season can become a global health event.

Understanding the health impact of wildfires – and learning how to use tools like PM2.5 sensors, portable CO2 monitors, and air cleaners – is becoming an essential part of protecting yourself, your family, and your community.

Why Are Wildfires Becoming More Frequent and Severe?

Wildfires are increasing in frequency, severity, and duration because hotter, drier conditions driven by climate change are colliding with accumulated fuels and expanding human activity in fire-prone landscapes.

Rising global temperatures, more frequent heat waves, and prolonged droughts dry out soils and vegetation, creating a larger and more combustible fuel load. In many regions, past fire-suppression policies have also allowed brush and dead trees to accumulate, making today’s fires burn hotter and spread faster.

At the same time, more people are living and working at the edges of forests and grasslands – the so‑called wildland–urban interface – which increases the chances that human activity will ignite fires and puts more homes, infrastructure, and lives in harm’s way.

These trends mean that even places that historically saw only occasional smoke may now experience repeated episodes of poor air quality each year.

How Do Wildfires Impact Air Pollution and Human Health?

Wildfire smoke is a dense mix of fine particles (especially PM2.5) and toxic gases that can irritate the eyes and lungs, worsen asthma and heart disease, and increase the risk of hospitalisation and premature death, especially on heavy smoke days.

Short-term health effects of wildfire smoke

Fine particles smaller than 2.5 micrometres (PM2.5) can travel deep into the lungs, bypassing many of the body’s natural defences. Short-term exposure to high wildfire smoke levels is consistently linked with spikes in emergency visits and hospital admissions for asthma attacks, chronic obstructive pulmonary disease (COPD) flare‑ups, bronchitis, pneumonia, and other respiratory problems.

People often notice symptoms such as coughing, wheezing, shortness of breath, chest tightness, sore throat, runny nose, headaches, burning eyes, and fatigue. Sensitive groups may experience these effects even when the air still looks relatively clear, because PM2.5 particles are too small to see.

A recent review of studies in Latin American cities found that wildfire-specific PM2.5 was associated with increases of roughly 1.7–7.7% in all‑cause, cardiovascular, and respiratory mortality for each 10 µg/m³ rise in exposure – a reminder that even short episodes can have serious consequences at the population level.

Several large studies also suggest that wildfire-derived PM2.5 may be more harmful to respiratory health than particles from other pollution sources, possibly because of its distinct chemical makeup.

Long-term health impacts of repeated smoke exposure

While the most visible impacts of wildfire smoke are short-term, growing evidence shows that repeated or chronic exposure can leave lasting marks on health. Long-term exposure to wildfire-related PM2.5 has been linked with increased risks of developing COPD, faster progression of existing lung disease, and possibly a higher risk of lung cancer.

Studies also suggest associations between wildfire smoke and cardiovascular diseases, including ischemic heart disease, arrhythmias, hypertension, and stroke, as well as adverse pregnancy outcomes such as preterm birth. 

Beyond the lungs and heart, the World Health Organization notes that PM2.5 from wildfire smoke is associated with impacts on the brain and nervous system, skin, gut, kidneys, eyes, and other organs, including potential cognitive effects.

Recent work also highlights the mental health dimension: wildfire smoke and disasters are linked to higher rates of depression, anxiety, post‑traumatic stress disorder (PTSD), substance use, and worsening of existing psychiatric conditions, especially when communities experience repeated seasons of smoke and evacuation.

Who Is Most at Risk from Wildfire Smoke?

Everyone can be affected by wildfire smoke, but some groups are at much higher risk of serious health impacts: children, older adults, pregnant people, outdoor workers, and anyone with asthma, COPD, heart disease, diabetes, or other chronic conditions.

Children breathe more air per kilogram of body weight than adults and their lungs are still developing, making them especially vulnerable. Older adults and people with pre‑existing heart or lung disease are more likely to experience severe symptoms, hospitalisation, or even death during heavy smoke episodes.

Pregnant people may face elevated risks of complications such as preterm birth when exposed to high levels of air pollution, including wildfire smoke, although the precise contribution of wildfires versus other sources is still being studied.

Wildfires also magnify existing inequalities: low‑income communities, Indigenous peoples, migrants, and those without access to clean indoor air or health care often face disproportionate exposure and have fewer options to relocate or create cleaner-air spaces.

What Are the Effects of Wildfires on the Environment and Climate?

Wildfires reshape landscapes by consuming vegetation, degrading soil and water, and releasing large amounts of greenhouse gases and black carbon that further warm the climate.

How do wildfires affect animals and ecosystems?

Intense fires can kill or injure wildlife directly, destroy nests and burrows, and remove food sources and shelter, forcing animals to flee or compete in new territories. Some habitats, such as rainforests and peatlands, may take decades or centuries to recover from severe burns.

At the same time, many ecosystems – from certain pine forests to some grasslands – evolved with regular, low‑intensity fires. These smaller burns can clear dense undergrowth, recycle nutrients, and create habitat mosaics that support biodiversity when managed carefully.

Climate‑driven megafires, however, often burn hotter and over larger areas than historic fires, overwhelming ecosystems’ ability to recover and increasing the risk of erosion, landslides, and invasive species.

How do wildfires affect communities and local economies?

Beyond smoke and immediate burns, wildfires damage homes, critical infrastructure, and local businesses, and can displace communities for months or years.

In the European Union, weather- and climate‑related extremes have caused an estimated EUR 822 billion in economic losses between 1980 and 2024, with recent years among the most costly; wildfires are a growing part of that picture.

In the United States, one analysis estimates that climate‑exacerbated wildfires may cost between 394 and 893 billion US dollars annually when health, infrastructure, and indirect economic impacts are fully counted.

Wildfires also leave deep psychological scars: studies of events such as the 2018 Camp Fire and other recent catastrophic blazes show elevated rates of PTSD, depression, and anxiety years after the flames are out.

How Can You Monitor Air Quality During Wildfire Season?

You can track wildfire smoke using public air quality indexes (AQI), low‑cost PM2.5 sensors, and portable air quality monitors – and CO2 monitors can help you understand how well‑ventilated an indoor space is, so you can balance keeping smoke out with avoiding stale, CO2‑heavy air.

Using AQI, PM2.5 sensors and portable monitors

Public AQI platforms such as AirNow, government monitoring networks, and community sensor maps provide near‑real‑time information about outdoor PM2.5 levels during wildfires. These tools help you decide when to stay indoors, when it might be safer to go outside briefly, and whether to cancel outdoor exercise or events.

Low‑cost PM2.5 sensors and portable air quality monitors are increasingly used in homes, schools, and workplaces to compare indoor and outdoor particle levels and to evaluate how well air cleaners and filters are working. Research shows that networks of such sensors can capture the sharp spikes in PM2.5 during wildfire events and help assess personal exposure.

Portable air quality monitors that measure PM2.5, volatile organic compounds (VOCs), temperature, and humidity can be carried between locations – for example, from home to work or to a gym – so you can choose spaces with cleaner air when you have options.

How do CO2 monitors fit into wildfire preparedness?

Carbon dioxide (CO2) monitors do not measure smoke particles, but they are a valuable proxy for how well a room is ventilated with fresh air. Because people exhale CO2, levels rise in crowded or poorly ventilated spaces and fall when more outside air is introduced.

Guidance from occupational health and public health agencies generally suggests that indoor CO2 levels consistently above about 1000–1500 ppm in occupied rooms indicate poor ventilation and should prompt action, such as reducing crowding, improving mechanical ventilation, or opening windows when outdoor air quality allows.

During intense wildfire smoke, people are often advised to close windows and reduce outdoor air intake to limit PM2.5 infiltration. This can cause CO2 to build up indoors. Using a portable CO2 monitor alongside AQI information lets you time short ventilation periods – for example, opening windows when outdoor smoke temporarily dips – so that carbon dioxide and other indoor pollutants do not accumulate excessively.

In workplaces, schools, and public venues, portable CO2 monitors can highlight rooms that are consistently stuffy and under‑ventilated, prompting building managers to adjust ventilation systems or occupancy levels. This supports both wildfire preparedness and broader goals of healthier indoor air.

What Can You Do to Protect Yourself from Wildfire Smoke?

The most effective protections are to reduce your exposure to smoke, clean the air you breathe, and plan ahead before fire season starts. Public health agencies around the world emphasise a combination of staying indoors when air quality is poor, using effective filtration, wearing appropriate masks when you must go outside, and monitoring air quality data.

At home: create a cleaner-air space

• Choose a room in your home to serve as a "clean room" during smoke events. Keep windows and doors closed, seal obvious gaps, and avoid activities that create additional indoor particles, such as smoking, burning candles, frying food, or vacuuming with a non‑HEPA vacuum.
• Use a portable air cleaner with a HEPA or equivalent high‑efficiency filter sized correctly for the room, or consider a well‑designed DIY Corsi–Rosenthal box if commercial units are unaffordable.
• If your home has a central HVAC system, ask a professional whether you can safely use filters rated MERV‑13 or higher, and set the system fan to run continuously during smoke events to maximise filtration.
• Use a PM2.5-capable air quality monitor in your clean room to see whether particle levels drop when you run your air cleaner. Pair it with a portable CO2 monitor so you can ensure CO2 levels do not stay very high for long periods; when outdoor smoke briefly improves, open windows for a short, intense ventilation burst.

On the go: masks, portable monitors, and planning

• Check the AQI before leaving home. If PM2.5 levels are high, postpone strenuous outdoor activities such as running or cycling, especially if you are in a sensitive group.
• If you must be outdoors during heavy smoke, wear a well‑fitting N95, KN95, or equivalent respirator. Cloth or simple surgical masks do not filter fine smoke particles effectively.
• Keep a supply of necessary medications (such as asthma inhalers) accessible, ensure they are in date, and have an action plan agreed with your health care provider for days when air quality is very poor.
• When possible, favour indoor spaces that filter and monitor their air – such as libraries or community clean‑air centres – over busy, poorly ventilated venues. A compact portable PM2.5 and CO2 monitor can help you compare different spaces in real time and choose the safest option available.
• If you live in a wildfire‑prone region, prepare a go‑bag with respirators, necessary medications, important documents, and basic supplies in case you need to evacuate quickly.

Living with Wildfire Smoke in a Warming World

Wildfires are no longer isolated natural disasters – they are a growing, climate‑driven public health emergency that affects air quality, ecosystems, economies, and mental health across entire regions and even continents.

Wildfire smoke’s fine particles and gases can damage virtually every organ system, with especially serious risks for children, older adults, pregnant people, outdoor workers, and anyone with heart or lung disease.

At the same time, you are not powerless. By understanding local wildfire risks, following air quality alerts, using air filtration, and making informed choices about when and where you spend time, you can substantially reduce your exposure.

Portable PM2.5 monitors and CO2 sensors are becoming practical tools for everyday life. They cannot replace public health warnings or medical advice, but they can give you a clearer picture of the invisible air around you – and help you act sooner to protect the people you care about.

‍

FAQ

1. What are the main health effects of wildfire smoke on humans?

Wildfire smoke can irritate the eyes, nose, and throat; trigger or worsen asthma and COPD; and increase the risk of heart attacks, strokes, and respiratory infections. On the worst smoke days, studies consistently find rises in hospital admissions and premature deaths, especially among vulnerable populations.

2. What are the short-term effects of wildfires on health and the environment?

Short-term, wildfires produce sharp spikes in PM2.5 and other pollutants that can make the air hazardous even far from the flames, while burning vegetation, damaging wildlife habitat, and contaminating soil and water with ash. People may experience acute breathing problems, chest pain, headaches, and psychological stress, particularly during evacuations.

3. What are the long-term health effects of wildfires?

Repeated exposure to wildfire smoke is linked to higher risks of chronic lung disease (including COPD), cardiovascular disease, adverse pregnancy outcomes, and possibly lung cancer. Long after the flames are out, many communities also face lasting mental health impacts such as PTSD, depression, and anxiety.

4. How do wildfires impact air pollution and human health globally?

Wildfire smoke can travel across borders and oceans, adding to background PM2.5 and ozone far from the fire zone. Canada’s 2023 wildfires, for example, are estimated to have contributed to about 87,000 premature deaths worldwide, underlining how smoke from one region can become a global health issue.

5. How do wildfires affect animals and ecosystems?

Severe fires can kill animals directly, destroy nesting sites, and fragment or eliminate habitat, while post‑fire erosion and invasive species further stress ecosystems. Some species and landscapes benefit from frequent, low‑intensity burns, but today’s large, hot megafires often exceed what these systems evolved to withstand.

6. What are the effects of a wildfire on communities?

Wildfires can destroy homes and infrastructure, disrupt livelihoods, and displace families for extended periods. They also strain health systems, worsen air quality for nearby and downwind communities, and are linked to long‑term mental health challenges and economic losses.

7. How do wildfires contribute to climate change?

When forests, peatlands, and grasslands burn, they release large amounts of carbon dioxide, methane, and black carbon into the atmosphere, adding to global warming. In some regions, repeated intense fires can turn ecosystems from long‑term carbon sinks into net carbon sources.

8. Can CO2 monitors detect wildfire smoke?

CO2 monitors do not measure smoke or PM2.5; they measure carbon dioxide from human breath and other combustion sources, mainly as an indicator of ventilation. During wildfires, CO2 monitors are most useful for showing when a room has poor fresh‑air supply so you can time ventilation breaks when outdoor smoke temporarily lessens.

9. Are portable air quality and CO2 monitors worth buying for wildfire season?

For many people, a good portable PM2.5 monitor plus a reliable CO2 monitor can be useful tools: they help you see whether your air cleaner is working, compare different indoor spaces, and understand when rooms are under‑ventilated. They do not replace official AQI alerts or medical care, but they can make invisible risks more tangible and support better everyday decisions.

10. How can I protect children, older adults, or people with asthma during wildfire smoke events?

Check air quality forecasts regularly, keep them indoors in a clean‑air room during heavy smoke, and use HEPA filtration where possible. Ensure medications (such as inhalers) are available and up to date, and consult their health care providers about action plans for poor‑air days; if symptoms worsen, seek medical attention promptly.

‍