Clean air shelters: A climate-adaptive measure to protect children’s respiratory health during wildfire events

THE EVOLVING THREAT OF POOR AIR QUALITY

Poor air quality is increasingly recognized as a significant threat that may especially impact disadvantaged children and communities. Over the next years and decades, climate change is expected to increase the likelihood of injury, disease, and death in part due to more frequent and intense heat waves, with a disproportionate impact on marginalized communities (1). As a result of the evolving climate crisis, Canada is likely to experience more frequent wildfires, resulting in severe environmental, economic and health consequences (1). Wildfire smoke is a complex mixture of particulate matter and gaseous pollutants. Fine particulate matter (PM_2.5) and volatile organic compounds (VOCs) found in smoke reach the alveoli in the lungs and smaller particles can directly enter the circulatory system, driving systemic inflammation with negative cardiorespiratory and central nervous system impacts (2). Even in communities far downwind from a fire, poor air quality due to wildfire smoke can lead to significant health effects including emergency department visits, hospital admissions, and deaths, often due to cardiorespiratory ailments (3).

CHILDREN ARE AT INCREASED RISKS OF ADVERSE HEALTH OUTCOMES DUE TO WILDFIRE SMOKE

Even short-term exposure to wildfire-related PM_2.5 is associated with increased risk of mortality (2). Children are at greater risk of the adverse health effects of air pollution due to behavioural, environmental and physiological factors: their lungs, organs and brains are still developing, they have smaller airways and more rapid breathing, and they often spend more time playing outdoors (4). While the specific mechanisms involved in risk exposure are complex, there is clear evidence that wildfire smoke poses significant risks to children’s health (5). Previous research has shown that paediatric asthma visits increase with wildfire events, as do visits for eye, throat, and nose symptoms, and lower respiratory symptoms such as wheezing (5,6). Emerging evidence indicates that wildfire smoke may also increase children’s susceptibility to respiratory viral infections and pneumonia (5).

HOW DO WE OFFSET THE THREATS FROM WILDFIRE SMOKE?

Recent research supports the effectiveness of indoor air filtration systems to reduce wildfire smoke exposure and improve indoor air quality and other jurisdictions in the USA and Australia have already started to investigate community clean air shelter strategies for wildfire events. The US Centers for Disease Control and Prevention (CDC) has outlined numerous high-quality studies which found beneficial impacts of implementing high-efficiency particulate air (HEPA) filtration devices to reduce circulating air pollutants that are prevalent in wildfire smoke in indoor environments (7). For example, the CDC summarized evidence from a study looking at the air quality in homes in British Columbia that were impacted by wildfire smoke 2004–2005. In approximately 90% of homes, indoor PM_2.5 was significantly lower when supplied with a HEPA filter. This is consistent with other reviews concluding that portable air cleaners can lower PM_2.5 exposure to benefit respiratory health during wildfire events, as indicated by a reduction in markers of airway inflammation, lessened impacts on lung function, blood pressure, and airway mechanics, and improved asthma symptoms in children (8,9).

Given the increasing number of wildfire smoke impacted days Canadian children are facing, as well as individual strategies to avoid exposures, community preparedness and public education are important considerations (10). Community planning and guidance should include information on:

• How to select and use HEPA with high Minimum Efficiency Reporting Values (MERV) ratings,

• Evaluation and upgrading of air circulation systems,

• Building control (e.g., closed/sealed doors and windows),

• Air conditioning, given that wildfire smoke and extreme heat events co-occur with increasing frequency,

• Outdoor event closures, and

• Prioritization of high-risk settings like schools and childcare centres, and considering school closures.

Public education should include information on:

• The importance of avoiding outdoor smoke exposures,

• How to minimize smoke exposure in homes, vehicles, and other spaces,

• Decision making strategies when health risks from heat and smoke are in conflict; for example, in the absence of air conditioning, when to open windows to circulate cool air versus when to keep them closed to reduce smoke exposure, and

• Information on when it may be appropriate to relocate.

SCHOOLS AS CLEAN AIR SHELTERS

Children, regardless of socioeconomic status, spend much of their time in school. Due to the global climate crisis that has already resulted in more frequent and longer-lasting heat events, wildfire season in North America now has considerable overlap with the school year, both in spring and fall. In many communities, schools may double as community centres where people gather outside of school hours. In some communities, particularly rural and remote locations which may be disproportionately affected by wildfire smoke, schools may be one of the only public buildings where community members can take refuge during disasters such as severe air quality degradation from wildfire smoke. Indoor air filtration and ventilation strategies in schools, specifically HEPA air cleaners or filters with higher MERV ratings, show promise in reducing children’s exposure to harmful fine particulate matter exposure. By advocating for high-quality air filtration in schools, paediatricians, parents, and communities can support critical access to clean air, provide a wildfire smoke-free clean air shelter, and improve equity in access to clean air for children of all social groups. This has the potential to mitigate increased health risks to disadvantaged children and improve health outcomes for all people within and across communities.

FUNDING

This work was not funded. LM was partially supported by a University of Alberta Women and Children’s Health Research Institute (WCHRI) Postdoctoral Fellowship Grant, which provided salary support. This funding organization was not involved in any aspect of the conduct, analysis, or manuscript preparation of this study; WCHRI takes no responsibility for the conduct or results of this manuscript.

POTENTIAL CONFLICT OF INTEREST

AH is a member of the editorial board. Another editor was assigned to handle the peer review of this manuscript. Outside the context of this manuscript, she also reports two CIHR Team Grants, a grant from the Lung Association of Alberta, one from the Alberta Medical Association and one from the Environmental Health Foundation of Canada as well as support from the American Thoracic Society and the Canadian Paediatric Society for travel costs. AH is also the past President of the Canadian Paediatric Society Section of Environmental Health (2021-2023) and a past Member of the American Thoracic Society Environmental Health Policy Committee (2019-2022). None of this support was used to generate this manuscript. There are no other disclosures. All three authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

AUTHOR CONTRIBUTIONS

TW contributed to the conception and design, drafted the initial manuscript, revised the work for critically intellectual content, and has approved the final version of the work. LEM contributed to the design of the work, drafted and revised the manuscript, revised the work critically for intellectual content, and has approved of the final version of the work. AH contributed to the conception and design of the work, revised the manuscript critically for intellectual content, and has approved of the final version of the work. All authors agree to be accountable for all aspects of the published content.