Understanding Fire Smoke's Pollution Impact And Severity

Wildfires are a significant cause of pollution, spreading harmful emissions and particles across vast distances and negatively impacting air quality. The smoke released during wildfires contains a mixture of gaseous pollutants, hazardous air pollutants, water vapour, and particle pollution. These particles, often no larger than one-third the diameter of a human hair, can infiltrate deep into the lungs, triggering severe health issues, including asthma attacks, heart attacks, and strokes. The impact of wildfire smoke is not limited to proximity, as it can travel thousands of miles, affecting individuals far from the fire's source. Climate change is contributing to more intense and prolonged fire seasons, exacerbating the challenge of maintaining outdoor air quality standards. Addressing this issue requires a multifaceted approach, including reducing greenhouse gas emissions and improving air monitoring systems and public health programs.

Particle pollution

PM2.5, or fine particles, are particles generally 2.5 micrometres in diameter or smaller, and they represent the main pollutant emitted from wildfire smoke, comprising approximately 90% of the total particle mass. These particles are so small that they can enter and lodge deep in the lungs and may even enter the bloodstream. This can affect every organ in the body and has been associated with premature death. Ultrafine particles are generally classified as having diameters of less than 0.1 micrometres. Coarse particles (PM10-2.5) are particles with diameters larger than 2.5 micrometres and smaller than or equal to 10 micrometres. They are primarily generated from mechanical operations such as construction and agriculture, but a small percentage is present in wildfire smoke.

A growing body of scientific evidence links exposure to wildfire smoke to various adverse health effects, with fine particles from wildfire smoke of greatest concern. Research has shown that vulnerable populations, including the elderly, children, people with pre-existing respiratory or cardiovascular disease, pregnant people, and outdoor workers, are at an increased risk of health effects from wildfire smoke. Studies of children in California found that those who breathed smoky air during wildfires experienced more coughing, wheezing, bronchitis, and colds, and were more likely to need to go to the doctor or hospital for respiratory causes, especially asthma. In addition, particle pollution can trigger asthma attacks, heart attacks, and strokes.

Wildfire smoke can spread air pollution not only in nearby areas but also thousands of miles away, causing breathing difficulties even in healthy individuals. Climate change is fueling longer and more intense fire seasons, leading to an increase in smoky conditions and contributing to total pollution levels. As a result, it will become more challenging to attain outdoor air quality standards and ensure clean air for all.

Gaseous pollutants

The chemical complexity of wildfire smoke makes it very different from typical industrial pollution. The quantity and composition of gaseous emissions from fires vary depending on factors such as the amount and type of fuel, meteorology, and burning conditions. For example, emissions from fossil fuel combustion contribute to the cycle of climate change and extreme wildfires. As CO2 emissions accumulate in the atmosphere, the risk and intensity of wildfires increase, further contributing to the release of gaseous pollutants.

One of the key challenges in understanding the impact of fires on air quality is the variability in emissions from fire to fire. This variability gives rise to uncertainties in determining the exact impact of individual fires. However, satellite-borne instruments that detect aerosol plumes and gaseous pollutants have provided valuable data on the air quality impacts of fires. These instruments offer daily coverage of almost the entire United States, aiding in the understanding of the chemical transformations that wildfire smoke undergoes in the atmosphere.

The criteria pollutants most relevant to wildland fire emissions include PM2.5, O3, and CO. While CO from fires is rarely a concern to the public, it can affect wildland firefighters, and recent studies have analysed exposure risks. Smoke plumes from wildland fires have been found to exceed EPA standards for both PM2.5 and O3, highlighting the health risks associated with exposure to gaseous pollutants.

Health effects

Smoke from fires is a serious health concern. It is composed of a mixture of gaseous pollutants, hazardous air pollutants, water vapour, and particle pollution. Particle pollution, or "particulate matter", is a general term for a mixture of solid and liquid droplets suspended in the air. These particles can be as small as one-third the diameter of a human hair and can enter and lodge deep in the lungs.

The health effects of smoke from fires are far-reaching and can be serious, even for healthy individuals. Exposure to smoke can cause breathing difficulties and trigger respiratory problems such as coughing, wheezing, bronchitis, colds, and asthma attacks. It can also lead to pulmonary inflammation and persistent coughing, phlegm, and difficulty breathing. Fine particles from smoke are of particular concern as they can be inhaled and enter the bloodstream, causing damage to vital organs such as the heart and lungs. This can increase the risk of heart attacks, strokes, and respiratory issues. Even short-term exposure to fine particles has been associated with an increased risk of exacerbating pre-existing respiratory and cardiovascular diseases, as well as premature mortality.

Children, older adults, and individuals with pre-existing conditions such as heart disease, diabetes, asthma, COPD, bronchitis, or other lung diseases are especially vulnerable to the health effects of smoke. Studies have shown that children who breathe smoky air during wildfires experience increased respiratory issues and are more likely to require medical attention. Additionally, pregnant people and those who exercise or work outdoors are also considered at-risk groups.

Smoke from fires can also have more immediate health effects, such as headaches, nausea, dizziness, and sinus, throat, and eye irritation. In high concentrations, exposure to certain gases in smoke, such as carbon monoxide, can lead to premature death. Furthermore, there is growing evidence of potential long-term neurological effects, with links being made between wildfire smoke and an increased risk of dementia and Alzheimer's disease.

It is important for individuals to take precautions to protect themselves from the harmful effects of smoke. This includes avoiding smoky areas, limiting physical exertion when exposed to high levels of smoke, and wearing masks to reduce exposure to fine particles and gases.

Climate change

Wildfires are drastically increasing and causing more damage to people and the environment across borders. According to the EU Commission, the 2022 and 2023 wildfire seasons were among the five worst on record. In 2024 alone, wildfires and vegetation fires generated around 1,940 megatonnes of carbon monoxide. Wildfires release a range of pollutants into the atmosphere, including black carbon, carbon monoxide, nitrogen oxides, and particulate matter. These pollutants can combine with existing air pollution, further increasing the harmful effects of smoke on human health and the environment.

Smoke from wildfires contains fine particles (PM2.5) that are approximately 2.5 µm in diameter or smaller and make up about 90% of the total particle mass. These fine particles are of significant health concern as they can enter the airways, lodge in the lungs, and trigger asthma or heart attacks. A growing body of scientific evidence links wildfire smoke exposure to various adverse health effects, including respiratory and cardiovascular issues. As climate change progresses, the probability of wildfires is expected to increase, making it crucial to understand the health consequences of exposure to wildfire smoke.

Wildfire smoke can travel great distances and impact the health of individuals far from the fire locations. For example, the smoke from Canada's 2023 fire season more than doubled the country's previous annual record for fire-related air pollution, affecting cities in the US and even across the Atlantic in Europe. Similarly, the 2020 wildfires in California, which included some of the state's largest and most destructive fires, threatened to undo nearly two decades' worth of emission reductions from power plants.

Air quality

Smoke from fires is a mixture of gases and fine particles produced when wood and other organic materials burn. The main pollutant in smoke is particle pollution, which is a mix of tiny solid and liquid particles suspended in the air. These particles can be grouped into two main categories: coarse particles (PM10-2.5) and fine particles (PM2.5). Coarse particles are generally larger than 2.5 micrometres and smaller than or equal to 10 micrometres, while fine particles are generally 2.5 micrometres or smaller.

Fine particles are the main pollutant emitted from wildfire smoke, comprising approximately 90% of the total particle mass. These particles are of the greatest health concern as they can get into the eyes and respiratory system, causing health problems such as burning eyes, a runny nose, and illnesses such as bronchitis. Fine particles can also aggravate chronic heart and lung diseases and have been linked to premature deaths in people with these conditions. Larger, more frequent, and intense wildfires are a growing public health problem, contributing to reduced air quality for people living nearby or downwind.

The smoke from fires can spread thousands of miles away, degrading air quality and creating hazardous conditions in areas far from the source. A 2021 study found that wildfire smoke is responsible for over 33,000 deaths annually across 43 countries, with many of these deaths occurring in cities far from the fires. In addition to the immediate health impacts, smoke from fires can also affect weather patterns. For example, tiny particles called aerosols that are released during a fire can impact cloud formation and precipitation.

To protect yourself from the harmful effects of smoke, it is recommended to stay indoors, close windows, and use air conditioning or air purifiers to maintain good air quality inside. When smoke levels are high, avoid activities that burn, such as using fireplaces or gas stoves, and avoid smoking or burning candles. If you have asthma or other lung diseases, follow your doctor's advice and medication plan, and seek medical attention if symptoms worsen.

To monitor air quality in your area, you can check the Air Quality Index (AQI) provided by organizations like AirNow or the U.S. EPA. These sources provide information on the current air quality and offer guidance on protecting yourself during periods of poor air quality.

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