Cross-Border Smoke: Canadian Wildfires Fuel Air Pollution Surge in US Cities

Canadian Wildfires. Credit | REUTERS
Canadian Wildfires. Credit | REUTERS

United States: Amidst the discourse of air quality, nations find themselves entwined in a shared fate. A recent revelation highlights the infiltration of wildfire smoke from Canada into major urban centres across the United States during 2023.

According to the latest World Air Quality Report from IQAir, a pioneering Swiss entity in air quality technology, residents of the United States were bestowed with relatively cleaner air in comparison to 75 percent of the 134 countries and territories under scrutiny. Nevertheless, the report unveils a disquieting reality: a significant portion of the United States grapples with air pollution levels almost twice the thresholds deemed acceptable by the esteemed World Health Organization (WHO). While the overall prevalence of unhealthy air witnessed a marginal increase from the preceding year, certain locales, exemplified by Milwaukee, endured a staggering surge of up to 50 percent.

Notably, the report identifies Canadian wildfire emissions as a primary catalyst behind many such surges, overshadowing the conventional culprits of climate deterioration, such as the fossil fuel industry, according to

The protracted exposure to air pollution stands as a formidable menace, contributing to an estimated 8 million fatalities annually worldwide while intricately intertwining with an array of health afflictions spanning respiratory ailments to malignancies. Studies underscore the detrimental impact of heightened air pollution on academic performance, evidenced by diminished student test scores and its correlation with a surge in emergency room admissions due to cardiac complications.

Christi Chester Schroeder, an authoritative voice in air quality science at IQAir, underscores the imperative of treating air quality akin to meteorological forecasts, advocating for vigilant monitoring before engaging in prolonged outdoor activities.

Drawing from a corpus of data culled from over 30,000 monitoring stations worldwide, IQAir’s report delineates the annual pollution averages predicated on the quantification of PM2.5, referring to particulate matter measuring 2.5 micrometers or smaller. These minuscule, imperceptible particles pose a grave health hazard upon inhalation, permeating both pulmonary and circulatory systems. WHO guidelines stipulate an annual threshold of 5 micrograms of PM2.5 per cubic meter of air, a benchmark exceeded nearly twofold in the United States.

Throughout the annals of 2023, the country grappled with an average PM2.5 concentration of approximately 9.1 micrograms per cubic meter of air, with metropolitan hubs such as Washington, DC, and New York City bearing the brunt of exacerbated pollution levels. The report unveils a stark escalation in pollution levels during summer, as soaring temperatures and stagnant atmospheric conditions converge to foster pockets of noxious air. Instances abound wherein PM2.5 levels in cities like Washington, DC, and Chicago surged beyond twofold, eclipsing WHO guidelines by over fivefold. Columbus, Ohio, clinched the ignominious title of the most polluted city for the second consecutive year, as per

However, amidst the prevailing gloom, a glimmer of hope emerges for the United States as discernible progress in forest fire containment translates into a milder fire season and discernibly cleaner air along the West Coast vis-à-vis antecedent years. Cities like Portland, Oregon, witnessed a notable 40 percent reduction in PM2.5 levels, whereas Los Angeles experienced a 10 percent decline. Of the top 25 populous cities in the nation, Las Vegas boasts the most pristine air quality.

Schroeder underscores the theme of transboundary haze, emblematic of smoke’s transcontinental sojourns. Canada’s torrid encounter with the worst wildfire conflagration in history occasioned the generation of voluminous soot-laden plumes, traversing national borders to shroud New York City in an ochre shroud and adversely impact air quality as far south as Florida.

Joel Thornton, an erudite luminary in atmospheric chemistry at the University of Washington, avers the unparalleled severity of Canada’s conflagrations in the previous year, attributing it to an alarming confluence of increasingly arid and warm climatic conditions. The ensuing ramifications portend an exacerbation of wildfires, constituting a harbinger of impending perils.

Canada Wildfires Fuel Air Pollution. Credit | REUTERS
Canada Wildfires Fuel Air Pollution. Credit | REUTERS

Recent actions of the Environmental Protection Agency (EPA) evidence a concerted impulse to perform air pollution reduction, with its primary manifestation in the transition from the annual PM2.5 standard from 19.1 microns per cubic meter of air to 9. Although that draft standard was a step forward compared to the WHO’s guidelines, advocates expect more extensive and real changes. Partisans in the Biden administration predict at least 4.500 avoided deaths each year, an enormous financial saving for healthcare costs as well. Hence, the EPA has upgraded the Air Quality Index, that is, the color-coded scale, designed for a user-friendly interface, providing information about air pollution from “good” to “hazardous”.

However, experts like Thornton caution against undue optimism, contending that wildfire occurrences imperil the realization of EPA benchmarks, thereby compromising the strides made under legislative frameworks like the Clean Air Act. A recent study elucidates the deleterious impact of wildfire smoke, undercutting nearly a quarter of the progress in air quality since the turn of the millennium.

Presently, the EPA abstains from factoring wildfire-induced pollution spikes in its regulatory calculus, invoking an “Exceptional Event Rule” that exempts natural calamities from distorting environmental metrics. With the advent of warmer climes and the imminent onset of fire season, strategic interventions in fire management emerge as indispensable safeguards against conflagrations and their concomitant airborne perils.


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