Air Pollution's Wildfire Smell: What Does It Mean?

Wildfires are a significant source of air pollution, which can have severe health consequences. Smoke from wildfires contains a mix of gases, particles, and chemicals that can cause respiratory and cardiovascular issues, especially in vulnerable individuals. The smoke can carry a range of smells, from the familiar campfire scent to a burnt plastic odor. While the campfire smell is caused by the burning of trees and leaves, the burnt plastic smell is due to chemical reactions between UV rays and smoke compounds. As wildfire smoke impacts air quality, it is crucial to protect indoor environments and take precautions to reduce exposure, especially for children, older adults, and those with heart or lung conditions.

Wildfire smoke contains a mix of gases, particles and chemicals

Wildfire smoke is a mix of gases, particles, and chemicals. It is a health concern, especially for those with pre-existing health conditions. The particles in wildfire smoke are primarily generated from combustion-related activities, such as wildfires, and their small size allows them to easily penetrate homes and buildings, increasing indoor particle concentrations. These particles can be grouped into two main categories: coarse and fine particles.

Coarse particles, also known as PM10-2.5, have diameters larger than 2.5 micrometers and up to 10 micrometers. While they are mainly produced by mechanical operations like construction and agriculture, a small percentage is present in wildfire smoke.

Fine particles, or PM2.5, are generally 2.5 micrometers in diameter or smaller. They represent the main pollutant emitted by wildfire smoke, making up about 90% of the total particle mass. These fine particles are of the greatest health concern as they can be inhaled deep into the lungs and may even enter the bloodstream, potentially impairing vital organs. This is particularly dangerous for individuals with cardiovascular or respiratory diseases, older adults, children, pregnant women, outdoor workers, and those of lower socioeconomic status.

The chemical composition of wildfire smoke can vary depending on factors such as the types of trees burned and the combustion temperature. This variation in composition may contribute to the differential health impacts observed. For example, recent toxicological studies suggest that wildfire particulate matter may be more toxic than equal doses of ambient PM2.5. As such, it is important to understand the specific health effects of wildfire smoke to implement effective air quality policies.

Additionally, particle pollution, or "particulate matter," is a general term for a mixture of solid and liquid droplets suspended in the air. It is a significant component of wildfire smoke and a principal public health threat. These particles can be composed of various substances, including acids (e.g., sulfuric acid), inorganic compounds (e.g., ammonium sulfate), organic chemicals, soot, metals, soil, or dust particles.

To reduce exposure to wildfire smoke, it is recommended to stay indoors with windows and doors closed, use air conditioning or air purifiers, and limit activities that can worsen indoor air quality. In some cases, evacuating the area may be necessary to ensure safety.

The health effects of breathing in wildfire smoke

Wildfire smoke is a complex mixture of gases, particles, and chemicals. The particles in wildfire smoke are primarily fine particles (also known as PM2.5), which are generally 2.5 micrometres in diameter or smaller. These fine particles are of the greatest health concern as they can travel deep into the lungs and may even enter the bloodstream. Ultrafine particles, which are generally classified as having diameters of less than 0.1 micrometres, are also present in wildfire smoke.

Individuals at greater risk of health effects from wildfire smoke include those with cardiovascular or respiratory diseases, older adults, children, pregnant women, outdoor workers, and those of lower socioeconomic status. People with chronic conditions such as asthma, Chronic Obstructive Pulmonary Disease (COPD), diabetes, chronic kidney disease, or heart disease are also at higher risk of experiencing health effects from breathing in wildfire smoke.

To reduce exposure to wildfire smoke, it is recommended to stay indoors with windows and doors closed if possible. Using an air conditioner or a portable air cleaner can also help improve indoor air quality. If staying indoors is not an option, wearing a well-fitting N95 or KN95 mask, taking frequent breaks, and adjusting work or exercise schedules to avoid the worst air conditions can help reduce the potential health impacts of breathing in wildfire smoke.

How to identify if there is a fire nearby

Wildfire smoke is a mix of gases, particles, and chemicals. The particles in wildfire smoke are primarily fine particles (PM2.5), which are generally 2.5 micrometres in diameter or smaller. These fine particles can easily penetrate homes and buildings, increasing indoor particle concentrations and potentially causing serious health issues, especially for those with pre-existing health conditions.

• Visible signs: During a wildfire, the concentration of particles in the air can increase to the point that particle pollution becomes visible to the naked eye. Look out for signs such as a haze or smoke in the distance, or an orange or reddish tint to the sky.
• Smell: Wildfire smoke has a distinct, acrid odour that can be noticeable even far from the source. If you smell something akin to burning wood or vegetation, it could be a sign of a nearby fire.
• Hearing: Listen for emergency vehicle sirens or loudspeakers. If there is a fire nearby, you may hear fire engines, police cars, or helicopters heading to the scene.
• Alerts and news: Stay informed by following local news channels, radio stations, and social media accounts. Local officials and news sources will provide updates and alerts about active fires in your area. Websites like InciWeb and the Fire Enterprise Geospatial Portal (EGP) provide information about wildland fire emergencies and incidents.
• Air quality: Monitor your local outdoor air quality using resources like AirNow.gov. During a wildfire, smoke and ash can severely impact the air quality, making it unhealthy to breathe. If you notice a sudden deterioration in air quality, it could be an indication of a nearby fire.
• Personal observations: If you live in an area with a high wildfire risk, it is important to stay vigilant. Keep an eye out for any signs of fire or smoke in your immediate surroundings, such as smoke plumes, embers, or glowing horizons.

Remember, fires can spread quickly, and your safety is the top priority. If you suspect a nearby fire, don't hesitate to evacuate or seek help.

Reducing exposure to smoke indoors

Wildfire smoke is a mix of gases, particles, and chemicals that can cause temporary health issues like eye, nose, and throat irritation, trouble breathing, or chest pain. Particle pollution is the main component of wildfire smoke, and these particles can easily penetrate homes and buildings, increasing indoor particle concentrations. Here are some ways to reduce exposure to smoke indoors:

Stay Informed and Prepare

Follow local news, official websites like AirNow, or your state air quality website for up-to-date information on active fires or wildfire smoke events. If you live in an area with a high wildfire risk, take steps to prepare for fire season, especially if you have children, older adults, or individuals with heart or lung disease in your household.

Stay Indoors and Limit Outdoor Air Entry

When advised to stay indoors, keep windows and doors closed to minimize the entry of smoke and particles from outdoors. Use fans and air conditioning to maintain a cool temperature. If you don't have air conditioning, consider visiting a library, grocery store, or public building to stay in a cooler and cleaner indoor space.

Use Air Filters and Masks

Consider investing in a non-ozone-producing air purifier or a high-efficiency particulate air (HEPA) filter to improve the air quality in your home. Ensure that the device is appropriately sized for the space you intend to use it in. Keep a supply of N95 respirator masks, which are effective against particulate matter, and wear them when necessary to protect your lungs.

Limit Indoor Air Pollutants

Avoid activities that can worsen indoor air quality, such as frying or broiling foods, smoking or vaping, vacuuming, burning candles or incense, or using a fireplace. Reduce the use of toxic chemicals, and opt for eco-friendly products that don't off-gas, such as mattresses and pillows.

Maintain Good Ventilation

Use mechanical ventilation devices such as bathroom or kitchen fans that vent to the outdoors. If possible, utilize heating, ventilation, and air conditioning (HVAC) systems with a fresh air intake to improve indoor air circulation. Regular cleaning and thorough ventilation are also important after a fire to remove residual smells and improve air quality.

The health effects of particle pollution

Particle pollution is the main component of wildfire smoke. It is a complex mixture of solids and aerosols composed of small droplets of liquid, dry solid fragments, and solid cores with liquid coatings. These particles may contain inorganic ions, metallic compounds, elemental carbon, organic compounds, and compounds from the earth’s crust. The size of the particles is directly linked to their potential for causing health issues.

Particles less than 10 micrometers in diameter are the most concerning as they can penetrate deep into the lungs and may even enter the bloodstream. These particles are known as PM2.5 and are the main pollutant emitted from wildfire smoke, comprising approximately 90% of the total particle mass. They are responsible for reduced visibility or haze.

Exposure to PM2.5 has been linked to a variety of adverse health effects, including respiratory symptoms such as irritation of the airways, coughing, and difficulty breathing. It can also cause lung inflammation and tissue damage. Short-term exposures of up to 24 hours have been associated with premature mortality, increased hospital admissions for heart or lung causes, acute and chronic bronchitis, asthma attacks, emergency room visits, and restricted activity days. These health effects are primarily reported in infants, children, older adults, and individuals with pre-existing heart or lung diseases.

In addition to the health effects of PM2.5, larger particles (known as PM10) also pose risks. PM10 includes dust from construction, landfills, agriculture, wildfires, industrial sources, wind-blown dust, pollen, and fragments of bacteria. Exposure to PM10 can lead to similar health issues as PM2.5, particularly in vulnerable individuals with heart or respiratory conditions, such as asthma or COPD.

To protect yourself from the health effects of particle pollution during wildfire events, it is important to monitor air quality and follow local recommendations. Staying indoors with windows and doors closed, using air conditioning or air purifiers, and limiting activities that worsen indoor air quality can help reduce exposure. In some cases, evacuation may be necessary to ensure your safety.

Frequently asked questions