Canadian wildfires increase asthma reliever use by almost 500%

Key takeaways:

• The Digihaler system collects and reports objective data on inhaler use.
• Findings suggest a causal relationship between air pollution from wildfires and short-acting beta 2 agonist reliever use.

ANAHEIM, Calif. — The wildfires in Canada in May and June 2023 were associated with short-term increases in asthma reliever use, according to a poster at the American College of Allergy, Asthma & Immunology Annual Scientific Meeting.

These increases reflect worse symptoms among patients with asthma, Autumn F. Burnette, MD, assistant professor in the division of allergy and immunology at Howard University Hospital, said during her presentation.

“Air pollution by wildfire smoke has been associated with asthma symptom worsening and exacerbations and an increased number of visits to the emergency department,” Burnett said. “This summer’s wildfires had a severe impact on air quality in the North and Northeast United States.”

For example, smoke from these wildfires triggered air quality alerts for approximately 128 million Americans by the evening of June 7. Also, ED visits associated with asthma were 17% higher than expected overall on days with wildfire smoke between April and August 2023.

The researchers noted a need to better understand the impact that this air quality can have on densely populated metropolitan areas, especially in relation to asthma symptoms. Also, the researchers cited the potential for digital technologies to aid asthma self-management as well as understand the impacts of environmental pollution.

Further, Burnette said, the high use of short-acting beta 2 agonist (SABA) reliever medication indicates worsening asthma. The Maintenance and Reliever Digihaler System (Teva Pharmaceuticals) can collect objective data on usage and inhalation parameters and aid patients in self-management.

These devices transmit data wirelessly to a mobile application that synchronizes with a digital health platform that stores and presents data to a clinician-facing web-based dashboard.

The researchers conducted a retrospective analysis of these data from 14 patients who used the Digihaler at least once between May 28 and June 17, 2023, while located in cities that were affected by the wildfires.

“Air quality index data at the corresponding locations were obtained from a public website,” Burnette said. “Average air quality index at the locations of patients included in the analysis exceeded 100, corresponding to unhealthy conditions in the period from June 6 to June 8.”

Specifically, average air quality index scores included 123 on June 6, which is considered unhealthy for sensitive groups, and 183 on June 7 and 163 on June 8, which are considered unhealthy for everyone.

The researchers also compared these data with individualized baseline average daily usage from week 1, defined as May 28 through June 3, and week 3, defined as June 11 through June 17.

“During [the wildfire] period, average SABA reliever usage across the cohort peaked at almost 500% of each individual’s baseline usage,” Burnette said.

Burnette said these findings strongly suggest a causal relationship between air pollution associated with wildfires and increased reliever use reflecting worsening asthma symptoms.

“Data from the Digihaler system can provide valuable insight into the impact of localized environmental events such as wildfires on individual disease status and could support preemptive clinical intervention,” Burnette said.

These data may help engage cross-sector partners and inform municipal policy as well, the researchers continued, in addition to the development of evidence-based early warning systems for events such as these wildfires, which are likely to occur more frequently.

Using digitally captured SABA data, the researchers noted, collaborators in Louisville, Kentucky, already have recommended enhancing the tree canopy, zoning for air pollution emission buffers, truck routing and a community asthma notification system.

“Data such as those presented here therefore have significant potential to benefit public health in the future,” Burnette said.