Veterinarians and air pollution: Rethinking what we’ve learned in a burning world

For decades, when veterinarians thought about air quality in the spaces where animals live and work, their mental checklist was short and specific: reduce dust, minimize ammonia, and ensure proper ventilation. Air quality was largely considered a barn-management issue, most relevant to high-density livestock housing or indoor kennel spaces. Tools of the trade, namely fans, bedding management, and cleaning schedules, were designed to keep air clear of irritating gases and particulate matter from manure, feed, and bedding. This made sense for the context in which most veterinarians worked and for the dominant air pollution risks recognized at the time.

But the world is changing and so is the air that our patients breathe. In the past decade, wildfires have become more frequent, more intense, and more destructive. Canada has been particularly vulnerable to wildfire activity, fueled by the changing climate. Canada is warming at twice the rate of the global average (1), leading to the expansion of the wildfire season, with fires igniting earlier and burning later in the year (2). The 2023 season was the worst Canada has experienced since comprehensive data reporting, with more than 12 000 fires burning over 17 million hectares (3). The current (2025) wildfire season has become the second-worst (4), with final data anticipated to be released at the conclusion of the season. Although fire destruction tends to be regional, wildfire smoke travels thousands of miles from its source, blanketing urban, suburban, and rural communities. For veterinarians, this shift means that the air quality risks most of us learned about in veterinary school are no longer sufficient to guide our clinical thinking or health messaging.

Wildfire smoke is a complex mixture of gases, volatile organic compounds, and fine particulate matter (PM_2.5). These fine particles are small enough to penetrate deep into the lungs, enter the bloodstream, and trigger systemic inflammation. Unlike larger dust particles that irritate the upper respiratory tract and are relatively easy for the body to clear, PM_2.5 bypasses these defenses. The result is a cascade of potential health effects: exacerbation of asthma and bronchitis, cardiovascular strain, impaired immune function, and even neurological impacts (5). Both short- and long-term exposure to PM_2.5 increases the risk of premature death. During the 2023 wildfires, 98% of Canadians experienced daily mean PM_2.5 concentrations exceeding World Health Organization recommended limits, with smoke persisting for 5 consecutive months (6). This exposure is estimated to have caused 1300 acute deaths and 8300 chronic deaths across the country. These findings underscore that air pollution is one of the most serious and widespread environmental public health threats of our time (7).

Although evidence from human medicine is compelling and animal studies are accumulating, much remains unknown. Documented effects include cardiopulmonary and neurologic changes in companion animals, immune suppression and reduced productivity in livestock, and worsening of respiratory signs and slower performance times in racehorses (8). These emerging data underscore both the vulnerability of animals to wildfire smoke and the critical research gaps that must be addressed to understand impacts and identify effective protective strategies, across species.

The shift to include PM_2.5 as a primary air quality threat requires rethinking our diagnostic and preventive strategies. Traditional air quality assessments in veterinary settings, including measuring ammonia concentrations in barns, checking bedding moisture, and monitoring for dust, are not enough. Instead, veterinarians must become familiar with using tools such as the Air Quality Index (AQI), understanding thresholds for concern, and interpreting particulate matter data. This involves educating ourselves, our clients, and staff on what “unhealthy” air means, how to recognize it, and what practical measures to take when wildfire smoke is present. It is also important to consider monitor placement and limitations if the nearest reporting station is distant or separated by a geographic barrier such as a mountain range. Where this occurs, veterinarians can advocate for installing supplemental monitors, for example PurpleAir¹, in areas that house animals (e.g., barns and dairies), or where animals are exercised or concentrated (e.g., racetracks).

The systemic effects of PM_2.5 mean veterinarians must think, and look, beyond respiratory health. We should be alert to subtle cardiovascular changes after prolonged smoke exposure, consider how poor air quality may exacerbate underlying conditions, and include air quality history in patient case workups. Anticipating these impacts also means preparing for surges in clinical demand during pollution events. Recent evidence suggests a 30 to 40% increase in sick pet appointments when baseline PM_2.5 concentrations below 5 μg/m³ increase to 40 to 50 μg/m³ (9). For performance animals, such as sport horses or working dogs, veterinarians should counsel clients on reduced exercise tolerance during and after smoke events. In production animals, smoke exposure may affect feed intake, reproductive performance, milk yield, and other indicators of productivity, which should be carefully monitored.

This expanded understanding also changes preventive measures that we recommend. For PM_2.5, solutions require both indoor and outdoor adaptations: modifying exercise schedules, advising clients on sealing barns or homes during heavy smoke days, or even installing high-efficiency air filters with a MERV rating of at least 11 to capture smoke and smog. In many cases, we must acknowledge that the only effective mitigation is reducing exposure altogether by relocating the animals themselves, an often costly or logistically challenging step, but one that may prevent serious health consequences.

Finally, this shift is not only about updating facts, but also about updating habits. Veterinarians who routinely check the AQI before scheduling outdoor work, who advise clients on smoke exposure risks during fire season, and who proactively monitor at-risk patients are operationalizing this new knowledge. These habits need to be taught, reinforced, and normalized. The transition will require continuing education programs, integration of climate and air pollution content into veterinary curricula, and development of clinical guidelines specific to wildfire smoke exposure.

Yet focusing only on mitigation at the point of care is not enough. The increasing intensity and frequency of wildfires are not inevitable acts of nature; they are driven by a combination of climate change, unsustainable land-use practices, and inadequate infrastructure resilience. Although veterinarians are not policymakers, they are trusted professionals who hold a unique position at the intersection of animal, human, and environmental health. This gives the profession both the credibility and the responsibility to speak up about broader environmental drivers of health issues that we see in practice.

Advocating for climate action is not outside the scope of veterinary medicine; rather, it is central to its future. Reducing greenhouse gas emissions, promoting sustainable land management, and supporting policies that build climate resilience are all interventions that ultimately protect the animals we serve. By lending our voices to climate policy discussions, collaborating with other health professionals, and modeling environmentally responsible practices in our own workplaces (10), veterinarians can address the problem at its source rather than only treating its consequences.

In conclusion, it’s time for our profession to move beyond the outdated binary comparison of “clean air” versus “dusty, ammonia-laden air.” Wildfire smoke is not merely a respiratory irritant; it is a complex environmental hazard with systemic consequences. It also reflects the broader planetary crisis driving these events. By re-examining what we learned about air quality in veterinary school, aligning our approach with the realities of a changing climate, and engaging in climate advocacy, we can protect the animals in our care, the people who depend on them, and the ecosystems that sustain us all. This is not only good medicine, but also the ethical path forward for a profession dedicated to health in all its forms.