Respiratory Outcomes of Firefighter Exposures in the Fort McMurray Fire: A Cohort Study From Alberta Canada

Systematic review of impacts of occupational exposure to wildfire smoke on respiratory function, symptoms, measures and diseases

BACKGROUND

Wildfire smoke contains numerous hazardous air pollutants which pose serious health risks to humans. Despite this, there has been a limited focus on the assessment of the acute physiological and longer-term respiratory effects of wildfire exposure on firefighters and other emergency workers. Therefore, we undertook a systematic review of the evidence about the respiratory impacts of occupational wildfire smoke exposure among wildfire fighters (WFF).

METHODS

Eligible studies from Medline, Embase and Scopus databases were included if they described the relationship between wildfire exposure and respiratory function, symptoms, measures and diseases amongst emergency personnel or firefighters who had responded to wildfires.

RESULTS

Twenty-six articles met the inclusion criteria. 24 out of 26 (22 out of 23 moderate/high quality) studies provided evidence of adverse respiratory effects, including reduced lung function, increased airway dysfunction and airway inflammation, upper and lower respiratory tract symptoms and increased asthma incidence related to wildfires or prescribed burns exposure among WFF and police responders. Fourteen out of 19 studies showed statistically significant declines in spirometry measures of lung function (mostly short-term studies). Two studies using complex lung function tests showed a significant effect on peripheral airway function.

DISCUSSION

This review found a convincing body of evidence that occupational exposure to wildfires or prescribed burns has both acute and possibly longer-term respiratory effects among WFFs and some other emergency personnel. Given that these events are increasing, more needs to be done to identify those most at risk and mitigate these risks.

The Effect of Wildfires on Asthma and Allergies

Climate change is a major driver of the frequency and severity of wildfires caused by extended periods of drought and hotter, drier weather superimposed on the legacy of fire suppression in the Mountain West of the United States. In recent years, increased wildfire smoke has negated the improvements in air quality made by clean energy transitions. Wildfire smoke is a complex mixture of gases and solids, a chief constituent of which is fine particulate matter (PM2.5). Exposure to PM2.5 is associated with adverse respiratory outcomes, including exacerbations of asthma and chronic obstructive pulmonary disease. In the face of increasing wildfire smoke exposures, it is critical that adaptation and mitigation strategies be put in place to minimize health effects. Individual strategies include modifying behavior and creating clean air spaces in homes to avoid wildfire smoke exposure. Community strategies include regulations promoting fire-resistant buildings and landscaping; establishing wildfire monitoring and alert systems; providing safe clean spaces where individuals can minimize wildfire smoke exposure and find evacuation routes; and creating health care response teams. Mitigation to prevent wildfires includes forest management and establishing monitoring systems and protocols to control forest fires in the wildland urban interface before they increase in size and intensity. Research into understanding the mechanism by which wildfire smoke mediates adverse health effects can inform guidelines to mitigate its health effects further.

Wildfire Smoke: Health Effects, Mechanisms, and Mitigation

Wildfires are becoming more frequent and intense on a global scale, raising concerns about their acute and long-term effects on human health. We conducted a systematic review of the current epidemiological evidence on wildfire health risks and a meta-analysis to investigate the association between wildfire smoke exposure and various health outcomes. We discovered that wildfire smoke increases the risk of premature deaths and respiratory morbidity in the general population. Meta-analysis of cause-specific mortality and morbidity revealed that wildfire smoke had the strongest associations with cardiovascular mortality (RR: 1.018, 95% CI: 1.014-1.021), asthma hospitalization (RR: 1.054, 95% CI: 1.026-1.082), and asthma emergency department visits (RR: 1.117, 95% CI: 1.035-1.204) in the general population. Subgroup analyses of age found that adults and elderly adults were more susceptible to the cardiopulmonary effects of wildfire smoke. Next, we systematically addressed the toxicological mechanisms of wildfire smoke, including direct toxicity, oxidative stress, inflammatory reactions, immune dysregulation, genotoxicity and mutations, skin allergies, inflammation, and others. We discuss wildfire smoke risk mitigation strategies including public health interventions, regulatory measures, and personal actions. We conclude by highlighting current research limitations and future directions for wildfire research, such as elucidating the complex interactions of wildfire smoke components on human health, developing personalized risk assessment tools, and improving resilience and adaptation strategies to mitigate the health effects of wildfires in changing climate.

Respiratory Diseases Associated With Wildfire Exposure in Outdoor Workers

Wildfires, including forest fires, bushfires, and landscape fires, have become increasingly prevalent, fueled by climate change and environmental factors and posing significant challenges to both ecosystems and public health. This review article examines the relationship between wildfires and respiratory diseases in outdoor workers, with a main focus on airway disease. In addition to the expected effects of direct thermal respiratory injuries and possible carbon monoxide poisoning, there are associations between wildfires and upper and lower respiratory effects, including infections as well as exacerbations of asthma and chronic obstructive pulmonary disease. A few studies have also shown an increased risk of new-onset asthma among wildfire firefighters. Outdoor workers are likely to have greater exposure to wildfire smoke with associated increased risks of adverse effects. As wildfires become increasingly prevalent globally, it is crucial to understand the various dimensions of this association. Furthermore, this review addresses preventive measures and potential interventions to alleviate the airway burden on individuals during and after work with wildfires events.

"Air That Once Was Breath" Part 2: Wildfire Smoke and Airway Disease - "Climate Change, Allergy and Immunology" Special IAAI Article Collection: Collegium Internationale Allergologicum Update 2023

BACKGROUND

Population growth and climate change have led to more frequent and larger wildfires, increasing the exposure of individuals to wildfire smoke. Notably, asthma exacerbations and allergic airway sensitization are prominent outcomes of such exposure.

SUMMARY

Key research questions relate to determining the precise impact on individuals with asthma, including the severity, duration, and long-term consequences of exacerbations. Identifying specific risk factors contributing to vulnerability, such as age, genetics, comorbidities, or environmental factors, is crucial. Additionally, reliable biomarkers for predicting severe exacerbations need exploration. Understanding the long-term health effects of repeated wildfire smoke exposures in individuals with asthma and addressing healthcare disparities are important research areas.

KEY MESSAGES

This review discusses the need for comprehensive research efforts to better grasp wildfire smoke-induced respiratory health, particularly in vulnerable populations such as farmworkers, firefighters, pregnant women, children, the elderly, and marginalized communities. Effective mitigation would require addressing the current limitations we face by supporting research aimed at a better understanding of wildfire smoke-induced airway disease.

Clearing the Air: Understanding the Impact of Wildfire Smoke on Asthma and COPD

Wildfires are a global natural phenomenon. In North America, wildfires have not only become more frequent, but also more severe and longer in duration, a trend ascribed to climate change combined with large fuel stores left from modern fire suppression. The intensification of wildfire activity has significant implications for planetary health and public health, as exposure to fine particulate matter (PM2.5) in wildfire smoke is linked to adverse health effects. This review focuses on respiratory morbidity from wildfire smoke exposure. Inhalation of wildfire PM2.5 causes lung injury via oxidative stress, local and systemic inflammation, airway epithelium compromise, and increased vulnerability to infection. Wildfire PM2.5 exposure results in exacerbations of pre-existing asthma and chronic obstructive pulmonary disease, with an escalation in healthcare utilization, including emergency department visits and hospitalizations. Wildfire smoke exposure may be associated with asthma onset, long-term impairment of lung function, and increased all-cause mortality. Children, older adults, occupationally-exposed groups, and possibly women are the most at risk from wildfire smoke. Future research is needed to clarify best practices for risk mitigation and wildfire management.

Factors by which global warming worsens allergic disease

Increased use of fossil fuels has led to global warming with concomitant increases in the severity and frequency of extreme weather events such as wildfires and sand and dust storms. These changes have led to increases in air pollutants such as particulate matter and greenhouse gases. Global warming is also associated with increases in pollen season length and pollen concentration. Particulate matter, greenhouse gases, and pollen synergistically increase the incidence and severity of allergic diseases. Other indirect factors such as droughts, flooding, thunderstorms, heat waves, water pollution, human migration, deforestation, loss of green space, and decreasing biodiversity (including microbial diversity) also affect the incidence and severity of allergic disease. Global warming and extreme weather events are expected to increase in the coming decades, and further increases in allergic diseases are expected, exacerbating the already high health care burden associated with these diseases. There is an urgent need to mitigate and adapt to the effects of climate change to improve human health. Human health and planetary health are connected and the concept of One Health, which is an integrated, unifying approach to balance and optimize the health of people, animals, and the environment needs to be emphasized. Clinicians are trusted members of the community, and they need to take a strong leadership role in educating patients on climate change and its adverse effects on human health. They also need to advocate for policy changes that decrease the use of fossil fuels and increase biodiversity and green space to enable a healthier and more sustainable future.

Asthma and landscape fire smoke: A Thoracic Society of Australia and New Zealand position statement

Landscape fires are increasing in frequency and severity globally. In Australia, extreme bushfires cause a large and increasing health and socioeconomic burden for communities and governments. People with asthma are particularly vulnerable to the effects of landscape fire smoke (LFS) exposure. Here, we present a position statement from the Thoracic Society of Australia and New Zealand. Within this statement we provide a review of the impact of LFS on adults and children with asthma, highlighting the greater impact of LFS on vulnerable groups, particularly older people, pregnant women and Aboriginal and Torres Strait Islander peoples. We also highlight the development of asthma on the background of risk factors (smoking, occupation and atopy). Within this document we present advice for asthma management, smoke mitigation strategies and access to air quality information, that should be implemented during periods of LFS. We promote clinician awareness, and the implementation of public health messaging and preparation, especially for people with asthma.

Perceptions of lung function surveillance in urban firefighters

BACKGROUND AND OBJECTIVE

Workplace health and safety (WHS) is an important responsibility falling on both employers and employees and is most effective when the perspectives of all stakeholders are considered. This study aimed to explore the facilitators and barriers to a voluntary workplace lung function surveillance program from the perspective of urban firefighters and describe their perceptions of its value.

METHODS

Using a qualitative, descriptive methodology, firefighters who had participated in a longitudinal lung function surveillance study were invited to participate in semi-structured interviews. Purposeful, maximum variation sampling was used to achieve diversity in those firefighters invited to participate. We used inductive content analysis to identify themes.

RESULTS

Interviews with 15 firefighters identified 3 main themes: (i) practical experience of surveillance (administration, communication, workplace culture change, convenience, acceptability, and appeal); (ii) value of surveillance (lung health efficacy and control, social support, workplace management support/motivations, contribution to global firefighter health); and (iii) contribution of surveillance to health (occupational risk, relevance in the context of total health, workability, and fitness and future value).

CONCLUSION

Practical and psychosocial facilitators and barriers to providing lung function surveillance in the fire service were identified. In addition to the personal benefits of detecting adverse lung health and allowing for medical intervention, factors known to positively influence firefighter workplace wellbeing, such as providing peace of mind, feedback on good work practices, motivation to utilize control measures, management commitment to health, and providing data to assist with global knowledge were valued aspects of longitudinal lung function surveillance.

The Effects of Wildfire Smoke on Asthma and Allergy

PURPOSE OF REVIEW

To review the recent literature on the effects of wildfire smoke (WFS) exposure on asthma and allergic disease, and on potential mechanisms of disease.

RECENT FINDINGS

Spatiotemporal modeling and increased ground-level monitoring data are allowing a more detailed picture of the health effects of WFS exposure to emerge, especially with regard to asthma. There is also epidemiologic and some experimental evidence to suggest that WFS exposure increases allergic predisposition and upper airway or sinonasal disease, though much of the literature in this area is focused more generally on PM2.5 and is not specific for WFS. Experimental evidence for mechanisms includes disruption of epithelial integrity with downstream effects on inflammatory or immune pathways, but experimental models to date have not consistently reflected human disease in this area. Exposure to WFS has an acute detrimental effect on asthma. Potential mechanisms are suggested by in vitro and animal studies.

In vitro data for fire pollutants: contribution of studies using human cell models towards firefighters' occupational

Firefighters are the principal line of defense against fires, being at elevated risk of exposure to health-relevant pollutants released during fires and burning processes. Although many biomonitoring studies exist, only a limited number of human in vitro investigations in fire risk assessment are currently available. In vitro studies stand out as valuable tools to assess the toxicity mechanisms involved following exposure to fire pollutants at a cellular level. The aim of the present review was to contextualize existing in vitro studies using human cell models exposed to chemicals emitted from fire emissions and wood smoke and discuss the implications of the observed toxic outcomes on adverse health effects detected in firefighters. Most of the reported in vitro investigations focused on monocultures respiratory models and exposure to particulate matter (PM) extracts collected from fire effluents. Overall, (1) a decrease in cellular viability, (2) enhanced oxidative stress, (3) increased pro-inflammatory cytokines levels and (4) elevated cell death frequencies were noted. However, limited information remains regarding the toxicity mechanisms initiated by firefighting activities. Hence, more studies employing advanced in vitro models and exposure systems using human cell lines are urgently needed taking into consideration different routes of exposure and health-related pollutants released from fires. Data are needed to establish and define firefighters' occupational exposure limits and to propose mitigation strategies to promote beneficial human health.

The Health of Firefighters Deployed to the Fort McMurray Fire: Lessons Learnt

Introduction: Firefighters were working in exceptionally difficult conditions during the Fort McMurray/Horse River fire in May 2016. Methods: From mid-May, we recruited firefighters from 13 fire services as they returned from the fire. In October 2016 we extended recruitment to all Alberta-based firefighters deployed to the fire. In December 2017-May 2018 we sent a first online follow-up: this concentrated on mental health supports. The second follow-up, in October 2018-January 2019, included screening scales for respiratory ill-health and PTSD. All three contacts included visual analogue scales for chest symptoms and the Hospital Anxiety and Depression Scale. We estimated exposure to PM2.5, and calculated an exposure mitigation index from reports of respiratory protective equipment (RPE). Results: We recruited 1,234 firefighters and examined the relation of respiratory symptoms to estimated particulate exposure. The relation was strong immediately post fire but weakened over time. We found less chest tightness and cough in those whose RPE in the first week mitigated exposure by at least 10%. We examined the relation between particulate exposure and mental ill-health from screening questionnaires and found those with high exposure (reflecting the ferocity of the fire) had poorer mental health scores. Firefighters reporting their "worst moment during the fire" was life threatening were more anxious at second follow-up. Overall both anxiety and depression scores increased at successive contacts, more so in those with mental ill-health recorded in physician billing records before the fire. Discussion: The results from this study overall suggest on-going fire-related health effects in a substantial minority of firefighters, similar to those reported in the longitudinal follow-up of firefighters after the collapse of the World Trade Centre. Self-reports of both respiratory symptoms and mental ill-health were strongly related, soon after the fire, to estimated particulate exposures. Anxiety increased over time since the fire in those who felt their life or safety had been threatened, underlining the need for ongoing support. Our conclusions about the benefits of rapid research relate particularly to the collection of biomarkers of exposure as quickly and widely as possible, and the establishment of a nominal list of participants before they are too widely dispersed.