Letter from Canada: Global warming and wildfire smoke pollution emerging as major threats to respiratory health

Like in many parts of the world, Canada has seen a dramatic increase in the number and size of wildfires over the last several summers, with deleterious effects on health, ecosystems and indigenous communities. The summer of 2023 was Canada's most destructive wildfire season ever recorded, with at least 6623 fires destroying over 18.4 million hectares of land (Figure 1).1 This shattered the previous record of 7.6 million hectares burned in 1989 and is more than six times the 10-year average of 2.5 million hectares. Increasingly devastating wildfire seasons are predicted, as the scale of the damage caused by wildfires has been on the rise for several decades. Indeed, the government of Alberta, Canada recently announced the start of the 2024 wildfire season to be 10 days earlier than the usual March 1 start. The intensified threat of wildfires is undoubtably related to global climate change and the commensurate record high temperatures dry forest conditions. In recent years, the annual average temperature in Canada has increased at roughly twice the global rate and last year Canada experienced its warmest summer in over 80 years. Wildfire smoke contains many pollutants that impact respiratory and cardiovascular health, including airborne particulate matter, carbon monoxide and polycyclic aromatic hydrocarbons. In Canada, wildfires are associated with increases in outpatient and emergency department (ED) visits and admissions for respiratory conditions, particularly in children. The far-reaching effects of Canadian wildfire smoke was felt hundreds of kilometres away, with smoke blanketing the northeastern United States, resulting in increased asthma-related ED visits in New York City and other major centres in the United States. Wildfire smoke has led to increasing use of rescue inhalers in patients with asthma and chronic obstructive pulmonary disease (COPD) and increased physician visits for lower respiratory tract infections. In addition to its effects on the respiratory system, wildfire smoke pollution has deleterious effects on numerous other aspects of health including an increased risk of lung cancer, cardiovascular disease, mental health and all-cause mortality. There has been a global focus on climate change and the role that healthcare plays in this emerging challenge. Inhalers are an important contributor to climate change, with pressurized metered dose inhalers (pMDIs) accounting for the greatest greenhouse gas emissions among all inhalers. Nearly 6 million people in Canada carry a diagnosis of asthma or COPD, and most are prescribed at least one inhaler. Though pMDI contributions to societal emissions are modest, pMDIs alone contribute 3.1% of emissions in the United Kingdom's National Health Service. In 2023, the Canadian Thoracic Society released a statement on reducing inhaler-related greenhouse gas emissions.2 It describes five goals in reducing the use of pMDIs, namely, 1. Improved objective testing of airways disease to reduce unnecessary inhaler use, 2. Improved adherence to guideline-directed care to avoid the overuse of short-acting bronchodilators, which are overwhelmingly prescribed as pMDIs, 3. Ensuring appropriate MDI technique to optimize disease control, 4. Prioritizing dry powder inhalers over pMDIs and 5. Educating patients about proper disposal of used inhalers through recycling and incinerating programs. More thoughtful consideration about inhaler choice and disposal is one way that Canada hopes to reduce greenhouse gas emissions to net zero by 2050. Despite advances in reducing exposure and improving therapeutic options, lung cancer remains the leading cause of cancer death in Canada. Most cases of lung cancer are diagnosed at an advanced stage, at which time treatment options are limited. Lung cancer screening in at risk populations with low dose computed tomography (LDCT) has been shown to detect more cases of early-stage lung cancer and to reduce both lung cancer mortality and all-cause mortality.3 Prospective data from The Pan-Canadian Early Detection of Lung Cancer Study confirmed that lung cancer screening was cost-effective for healthcare systems, with an estimated a cost savings of $6.65M by screening eligible residents for 3 years in the province of Alberta alone. In 2016, The Canadian Task Force on Preventive Health Care recommended screening adults aged 55–74 with a 30 pack-year smoking history who currently smoke or quit less than 15 years ago with LDCT annually, for three consecutive years. Subsequently, 9 of the 10 Canadian provinces have initiated lung cancer screening programs for high-risk individuals. Screening has been fully implemented in British Columbia and Ontario since 2022 and two other provinces have begun pilot projects. An interim analysis from the first pilot study in Ontario showed a lung cancer detection rate of 1.7% of high-risk individuals, with 71% of these considered to be early-stage I or II cancers.4 Canada, like many G20 countries, faces challenges with projected physician workforce planning, both in primary care and in generalist specialist care. The issue is most pronounced in rural areas in all regions of the country and, to address this challenge, several Canadian medical schools have implemented modern pedagogical curricula rooted in generalism. Residency speciality training in Canada has also been adapted through an initiative called competency by design (CBD). CBD is based on the model of competency-based medical education, which aims to enhance learning and assessment by facilitating clear learning objectives, longitudinal mentorship and earlier detection of knowledge gaps. This strategy ensures that physicians graduate with the necessary competencies to meet local needs. Residency and fellowship training is divided into stages, each with their own learning objectives, called entrustable professional activities (EPAs). Each EPA must be directly observed, and feedback given in person or through an electronic portfolio prior to advancing to the next stage. This allows for longitudinal coaching that facilitates performance improvement, as well as identifying knowledge gaps. Trainees also have a designated mentor, whom they meet with regularly to ensure that they are progressing accordingly and to address any concerns. At scheduled intervals during training, a competency committee provides feedback and recommendations regarding promotion of the trainee to the next stage of residency training. Respiratory healthcare in Canada, as in many other parts of the world, faces several challenges but, through ongoing research, evolving health learning systems, advances in medical education and the national leadership of our accrediting bodies and professional organizations, we are increasingly well positioned to deal with these challenges in the years ahead. None declared.

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