Image courtesy of Climate Visuals

TL;DR — Wildfires have a severe impact on air quality and, consequently, on human health. While wildfire smoke’s damage can vary depending on its composition and density across an area, research shows that it may not only have short-term damage but perhaps also a cumulative negative impact on human health. However, by recognizing the need for real-time air quality monitoring to collect data and understand pollution exposure during wildfires, we can protect public health.

Wildfires as a global issue

Wildfires have grave consequences as a major issue around the globe. While wildfires can cause damage to human and environmental health in a variety of ways, the air pollution from wildfire smoke itself accounts for a significant portion of wildfires’ lasting impacts.

Globally, wildfire smoke is estimated to cause over 339,000 premature deaths a year – far more than those who lose their lives directly in these blazes”

— European Commission

According to research from Stanford, wildfire smoke not only negatively affects air quality during wildfires but also negates decades of clean air gains because of the extreme pollution levels that people are exposed to.

We have seen wildfires grow in intensity and frequency in recent years as part of our changing climate — making it highly important that we both understand the impacts of wildfire smoke and work to mitigate its negative impacts.

Understanding the impact of wildfire smoke on air quality

Wildfire smoke significantly degrades air quality around where the fire is burning and can also affect the air hundreds or thousands of miles away as the smoke travels.

With large fires, the smoke can rise many kilometers into the stratosphere and spread across entire regions, causing air pollution in areas far away from where the flames actually were”

— European Commission

Wildfire smoke is composed of a variety of dangerous air pollutants, including gaseous pollutants like carbon monoxide, hazardous air pollutants like polycyclic aromatic hydrocarbons (PAHs), and particle pollution, along with water vapor. 

Particulate matter air pollution, especially fine particulate matter (PM2.5) is responsible for a large component of the detrimental health impacts associated with wildfire smoke, and research on the impacts of PM primarily serves as the basis for our current scientific understanding of wildfire smoke exposure. Read our air quality measurements series blog focusing on PM here to learn more about the pollutant's impacts.

The variation in air pollution due to a wildfire depends on the fire’s severity and proximity as well as whether the fire burned in a more rural or inhabited area.

[The components of wildfire smoke] differ depending on what material is feeding the flames. Smoke from fires that burn through poison oak and poison ivy may contain traces of irritants from those plants. Smoke can also pick up chemicals from plastic and other humanmade materials when wildfires burn through cities or housing developments”


This can also help explain why the air quality impacts of prescribed or controlled burns tend to be less severe than those of unprescribed wildfires.

Because wildfire smoke contains a mixture of different pollutants and can vary in its composition — such as according to what types of materials were primarily burned in the fire — its health outcomes can also vary widely.

One key health outcome is the way that wildfire smoke exposure increases the risk of cardiovascular and respiratory-related effects in response to wildfire smoke exposure.

As wildfire smoke density increases, so too does the relative risk for both cardiovascular and respiratory effects as an outcome of smoke exposure. (Image source: US EPA, adapted from Wettstein et al. 2018)

Fine particulate matter particles act as respiratory irritants and exposure to high concentrations can result in:

  • Persistent coughing
  • Phlegm
  • Wheezing
  • Difficulty breathing
  • Transient reductions in lung function
  • Pulmonary inflammation
Particle pollution may also affect the body’s ability to remove inhaled foreign materials, such as viruses and bacteria, from the lungs. Short-term exposures (i.e., days to weeks) to fine particles are associated with increased risk of exacerbation of pre-existing respiratory and cardiovascular disease, as well as premature mortality”


Some research also shows additional negative effects due to cumulative exposure to wildfire smoke, but these studies have been mostly relegated to wildland firefighters whose exposure may not represent that of the general population. Thus, more research is needed.

The table above displays known outcomes of wildfire smoke exposure, with the most existing evidence showing the outcome of short-term exposures. However, as devastating wildfires become more frequent in our world today, we may start to better understand the impacts of cumulative short-term exposure and long-term exposure to wildfire smoke. (Image source: US EPA)

It is also important to note that these negative health outcomes do not affect all individuals equally. Research shows that wildfire smoke exposure may disproportionately impact:

  • Children and older adults
  • Those with cardiovascular or respiratory disease
  • Those who are pregnant
  • Those who work outdoors
  • Those of lower socioeconomic status

Read our health impacts deep dive blog here to learn more about the multitude of ways that air pollution impacts human health.

The effects of recent wildfires on air quality in the United States and Canada

While wildfires are especially prevalent in certain regions, such as the western United States, pollution from wildfires can impact areas all over the globe.

Notable wildfires have occurred in U.S. and Canada over the past decade. Just recently, Canadian wildfires are still burning and have severely impacted air quality across Canada, the U.S., and beyond.

The image above from NASA illustrates just how significantly wildfire smoke can move across the globe. Smoke from the Canadian wildfires traveled across the Atlantic Ocean and is seen nearing Portugal and Spain in this satellite image, showing just how global one wildfire’s impacts can be. (Image source: CBS News)

Other devastating fires in recent years include the 2021 Dixie Fire and the 2020 August Complex Fire in California. The Dixie Fire burns more than 463,000 acres and destroyed or threatened tens of thousands of structures. The August Complex Fire burned 1,032,648 acres.

The importance of real-time air quality monitoring for wildfire season

The significance of having air quality monitoring in place during wildfires cannot be understated. 

You can’t manage what you can’t measure — without knowing the actual air quality impacts from wildfire smoke, it is very difficult to know exactly what levels of harmful pollutants people are breathing in and how they can safely reduce their exposure.

Real-time monitoring enables both a timely response and public health protection.

It is essential to have multiple monitoring points as part of a hyperlocal, high-resolution network. Because wildfire smoke concentration can change rapidly during a fire, data must be collected frequently.

Wildfire smoke and associated air pollutant concentrations can also change due to terrain in different areas.

Terrain also affects smoke concentrations. For example, as the sun warms mountain slopes, air is heated and rises, bringing smoke and fire with it from lower elevations affected by smoke. After sunlight passes, the terrain cools and the air descends, creating a down-slope airflow that can alter the smoke dispersal pattern. Daily cycles can help predict repeating patterns of smoke exposures in communities”


Having monitoring points further away from the area immediately impacted by the fire is crucial because of wildfire smoke’s ability to travel thousands of miles, as seen above.

Smoke from wildfires can travel thousands of miles, harming people who don’t live directly in wildfire-prone areas”

— UCLA Newsroom

The role of air quality data in decision-making and emergency planning

Having a dense air quality monitoring network that collects high-resolution data is a vital part of effective decision-making during times of high air pollution such as wildfires.

Brightline Defense, an environmental justice non-profit organization based in San Francisco, deployed low-cost sensors in communities that have long experienced poor air quality, such as the South of Market (SoMa) neighborhood. These sensors captured the impacts of the devastating 2020 wildfire season on the air quality experienced in this area.

To learn more about Brightline Defense’s air quality monitoring network, read our customer story here.

Boulder, Colorado experienced a devastating wildfire known as the Marshall Fire in 2021 that destroyed over 1,000 homes and spread over thousands of acres. After the fire, residents’ air quality concerns grew, and Boulder County Public Health decided to deploy a low-cost sensor network to better capture the impacts and supply residents with real-time data.

Residents also had concerns about the impacts of air pollution from the debris removal process. 

The air quality monitoring network provided access to real-time data and delivered alerts to residents in partnership with the city of Denver’s Love My Air program. Read more about Boulder County Public Health’s air quality monitoring network here.

Read our blog here to learn more about different projects’ innovative use of low-cost sensors to collect data and drive decision-making during wildfires.

Protecting vulnerable populations through real-time air monitoring

People are not affected equally by air quality events such as wildfires, and it is important to determine and understand the air pollution levels that may be experienced by different groups surrounding the location of a fire.

This is why local, high-resolution data is greatly important — only having data from regional air quality monitors does not truly tell us the exposure faced by different communities.

Having timely alerts should air quality reach a harmful level is one key step. 

With timely alerts, individuals in areas with wildfire smoke can avoid doing strenuous activities or exercising outdoors, going outdoors altogether in some cases, and taking other preventative measures like those listed here to protect their health.

A variety of platforms can be used, such as AirNow, to disperse this information.

Tools such as the Air Quality Index (AQI) can also be very useful to easily translate the meaning of different air pollution levels and any activities that must be avoided due to the risk.

Graphics like the one above help to disperse air quality information and key practices that individuals should take to protect themself during periods of wildfire smoke, which can be vital in reducing harm, illness, and death associated with the fire. (Image source: California Air Resources Board)

The need for action: Wildfires, air quality, and public health

Wildfire smoke has severe impacts on human health, both immediately during the fire as well as following this initial exposure.

This is why it is crucial to build resilient air quality monitoring networks and input effective systems to help disperse air quality information to protect public health and reduce smoke exposure.

With our changing climate, wildfires are only becoming more frequent, and many now occur outside of the traditionally thought of “wildfire season”, meaning it is more important than ever to learn how to protect human and environmental health.

Read our blog on the link between wildfires and climate change — and what it means for air quality and human health in the long term — to learn more.

Interesting in measuring air quality during wildfire season to better understand exposure and protect public health? Learn more about air quality monitoring for wildfire smoke here and how our wildfire smoke emergency response kit can be used for effective emergency response. Additionally, watch our Wildfires, Smoke and Air Quality Webinar here to learn more about building an effective and resilient air quality monitoring network for fire season.