Air filters cost effective for wildfire-related asthma problems in some areas
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Key takeaways:
- Depending on the rebate amount for air filters, some regions in British Columbia did achieve cost-effectiveness.
- Use of air filters could prevent poor asthma outcomes from wildfire smoke exposure.
In British Columbia, a rebate of $100 for an air filter that lowers indoor smoke concentrations was deemed cost effective in multiple regions, according to results published in American Journal of Respiratory and Critical Care Medicine.
“The [British Columbia] government launched a new initiative in June 2023 to provide 8,000 publicly funded air conditioning units to low-income and medically vulnerable individuals,” Amin Adibi, MSc, research scientist and PhD student at the University of British Columbia, and colleagues wrote.
“Our results suggest that a similar program should be implemented for HEPA filter air cleaners to mitigate the impacts of extreme wildfire events in [Health Service Delivery Areas (HSDAs)] with recurrently high wildfire smoke exposure,” Adibi and colleagues continued.
In this study, the researchers assessed individuals living in British Columbia, Canada, to determine if government rebates for HEPA filters are cost effective over 5 years (2018-2022) when considering asthma control, exacerbation severity and mortality in a Markov model, all of which are complications linked to wildfire smoke.
Researchers informed their model with wildfire smoke PM2.5 concentrations from a preexisting Canadian model, as well as relevant literature.
The cohort was divided according to HSDA (n = 16) to find out how costs and quality-adjusted life-years (QALYs) changed with different rebates.
Within the total cohort, researchers observed a wide range of average daily wildfire-related smoke concentrations (2.5 μg/m3 to 410.6 μg/m3). Each of the 16 HSDAs had different smoke concentrations from year to year.
Assuming continuous use of the HEPA filter, each individual had costs of $83.34 and QALYs of 0.0011.
The incremental cost-effectiveness ratio varied across the 16 HSDAs ($40,509 to $89,206 per QALY), and the average ratio came out to be $74,652 per QALY, according to researchers.
Researchers further found a wide cost-effectiveness probability range (0.1%-74.8%) when analyzing the 16 HSDAs.
Over the 5-year period, researchers observed projected prevention of three adverse outcomes related to asthma with use of HEPA filters: 4,418 fewer exacerbations that need systemic corticosteroids, 643 fewer ED visits and 425 fewer hospitalizations.
An incremental cost-effective ratio under the willingness-to-pay threshold ($50,000 per QALY) was achieved by 14 HSDAs when given a $100 rebate, whereas only one HSDA (Kootenay Boundary) achieved this when given a full rebate. Of the HSDAs, Kootenay Boundary was the most wildfire-prone, according to researchers.
In all HSDAs, researchers noted that a full rebate plus operation of HEPA filters was not cost effective when daily PM2.5 was over 25 μg/m3; however, a $30 rebate plus operation was cost effective in four HSDAs.
“To the best of our knowledge, this is the first cost-effectiveness analysis of a government-sponsored HEPA filter rebate program designed to prevent wildfire smoke-related asthma exacerbations and improve asthma control,” Adibi and colleagues wrote.