As parts of the world are experiencing the impact of wildfire smoke first-hand, tens of millions of people in North America have been forced to confront dangerous air quality levels. The cause? Intense wildfires ravaging across Canada, particularly Quebec, where 160 fires are actively burning.

As forests burn, large volumes of smoke are released into the atmosphere, impacting air quality locally and often hundreds, even thousands, of miles away. From Toronto to New York, vast metropolitan areas have been shrouded in an ominous orange haze, briefly earning them the dubious distinction of having the worst air quality worldwide.

So what are the mechanisms behind smoke dispersion and the implications for air quality and human health?

How does wildfire smoke spread?

Smoke from wildfires consists of a mixture of gases and microscopic particles produced when organic matter burns. The spread of smoke is primarily dictated by weather patterns and atmospheric conditions.

When wildfires ignite, smoke is released and can ascend to high altitudes due to the heat of the fires. This smoke can then travel great distances, carried by wind currents. It’s not uncommon for wildfire smoke to cross state lines, oceans, and even continents. For instance, smoke from the 2020 US West Coast wildfires was observed over Northern Europe, illustrating the transcontinental reach of such events.

Smoke composition and its effects on air quality

Wildfire smoke is composed of carbon dioxide, carbon monoxide, water vapor, and particulate matter. Of these, particulate matter—specifically PM2.5, or particles with diameters that are 2.5 micrometres and smaller—is the greatest concern for air quality and health. PM2.5 particles are small enough to be inhaled into the deepest parts of the lungs and even into the bloodstream, causing various health problems.

High concentrations of these particles significantly degrade air quality, creating hazy conditions and reducing visibility. This can result in an Air Quality Index (AQI) that exceeds safe levels for humans and animals.

Impact on human health

Exposure to wildfire smoke can lead to a range of health effects, some immediate and others potentially long-term. These can range from minor symptoms like coughing and difficulty breathing, to more severe issues such as exacerbating chronic heart and lung diseases. People with asthma or other respiratory conditions, the elderly, and children are particularly vulnerable.

How far can wildfire smoke travel?

The extent of smoke dispersion is dependent on the size of the fire and prevailing weather patterns. In some instances, smoke from severe wildfires in western North America has been reported to affect air quality on the East Coast. In 2019, smoke from Australian bushfires circumnavigated the globe, returning to its origin – a clear demonstration of the far-reaching effects of these fires.

Mitigating the impact

As our climate changes and the incidence of large-scale wildfires potentially increases, understanding and mitigating the impact of wildfire smoke becomes crucial. Measures include improving forecasting of smoke spread, raising public awareness of the health risks, and implementing strategies to reduce the incidence and severity of wildfires.

Furthermore, individuals can take action by staying informed about the AQI in their area, especially during wildfire season, and taking necessary precautions like staying indoors and using air purifiers during periods of poor air quality.

IFSJ comment

The smoke from wildfires can have a profound and far-reaching impact on air quality, traveling great distances and impacting the health of people far removed from the fires themselves. As we grapple with the reality of an ever-changing climate, it becomes increasingly necessary to understand and address this smoky consequence of wildfires.