Sustained Effects on Lung Function in Community Members Following Exposure to Hazardous PM2.5 Levels from Wildfire Smoke

Abstract

Background: Extreme wildfire events are becoming more common and while the immediate risks to susceptible populations (i.e. elderly, asthmatics) are appreciated, the long-term health effects are not known. Historically, wildfire smoke exposure studies have consisted almost exclusively of retroactive health reports, including emergency department visits, hospital admissions, provider visits with emphasis on specific ICD codes. In 2017, the Seeley Lake, MT area experienced unprecedented levels of wildfire smoke from July 31 to September 18, with a daily average of 220.9 mg/m3. The aim of this study was to provide health assessments in the community as temporally close to the fires as possible and evaluate potential adverse health effects with multiple visits over two years. Additionally, the members of the community of Thompson Falls, MT were evaluated in 2018 as a comparison, due to their Northern Rockies location and 5-fold less smoke exposure during the same time period.Methods: Using the IPHARM (Improving Health Among Rural Montanans) infrastructure and experience to perform mobile health screenings, the Seeley Lake community was visited following the fires. The study resulted in the recruitment of a cohort (n=95, average age: 63 years), for a rapid response screening activity shortly following the wildland fire event, and two follow-up visits in 2018 and 2019. Results: The community experienced 35 of 49 days with >150 mg/m3 of PM2.5 which fell within the range of the Environmental Protection Agency designation of “very unhealthy”. Analysis of spirometry data found a significant decrease in lung function (FEV1/FVC ratio: forced expiratory volume in first second/forced vital capacity) and a more than doubling of participants that fell below the lower limit of normal (13.2% in 2017 to 41.7% in 2018) one year following the wildfire event, and remained decreased two years (35.9%) post exposure. In addition, observed FEV1 was significantly lower than predicted values. Conclusion: These findings suggest that wildfire smoke can have long-lasting effects on human health. As wildfires continue to increase both here and globally, understanding the health implications is vital to understanding the respiratory impacts of these events as well as developing public health strategies to mitigate the effects.

Disproportionate Impacts of Wildfires among Elderly and Low-Income Communities in California from 2000–2020

“…Another key finding in our study was that Census tracts with a higher fire frequency and greater proportions of burned area had substantially higher proportions of older (age > 65) residents. This is an important finding given that it may be more difficult for such residents to expeditiously evacuate during a wildfire, and because this age group is particularly vulnerable to health-related impacts of short-term wildfire smoke exposure [ 38 , 39 , 40 ] given their higher prevalence of pre-existing lung and heart diseases and due to important health-protective physiologic processes that decline with age [ 38 ].…”

Impact of recent catastrophic bushfires on people with asthma in Australia: Health, social and financial burdens

“…Importantly, it is likely that these catastrophic fires will have long‐term health effects 2 . Exposure to woodsmoke may cause long‐lasting lung and airway injuries and contribute to the progression to irreversible airflow limitation 6 …”

“…2 Exposure to woodsmoke may cause longlasting lung and airway injuries and contribute to the progression to irreversible airflow limitation. 6 The findings highlight the need for effective primary and secondary preventative measures in people with asthma. Monitoring for long-term respiratory consequences is essential to quantify and qualify the extent of the impact and use this information to explore preventive measures.…”

Risk and burden of hospital admissions associated with wildfire-related PM2·5 in Brazil, 2000–15: a nationwide time-series study

“…15 Emerging evidence shows that even shortterm exposures to high concentrations of PM 2•5 from wildfires can trigger adverse health outcomes including coughing, asthma, heart attacks, stroke, decrease in lung function, hospital admissions, and premature death. [16][17][18] For asthma, a review study summarised that health outcomes related to wildfire PM 2•5 were more severe than those from typical mixture PM 2•5 . 19 Compared with the vast literature on the health effects of total PM 2•5 generally, the health effects of wildfirerelated PM 2•5 are much less thoroughly explored, although they are an important issue in Brazil.…”