Prescription Inhaler Fills Surged During West Coast Fires This Year
Key takeaways:
During weeks that West Coast regions experienced poor air quality due to fires, fills for short-acting beta agonist inhalers increased by about 30%.
Across all three states we looked at (Washington, Oregon, and California), average fine particulate matter concentration was three times worse in regions that experienced poor air quality.
Those who’ve had long-term exposure to air pollution from fires may be more at risk of dying from COVID-19 if they become infected with the virus.
Amidst the thick of the COVID-19 pandemic, 2020 also brought massive fires and dangerous air quality to much of the western half of the country. But even though much of the population was able to stay inside, close their windows, and hide from the smoke, some people were forced to turn to prescription medications to fare this fire season.
New research from GoodRx observing air quality’s effect on prescription fills for inhalers shows just how much these fires may have impacted some. In fact, in areas with poor air quality, fills for short-acting beta agonists, which are used for quick relief or prevention of asthma or COPD, were about 30% higher than they would have been without the fires.
In this analysis, the GoodRx Research team observed the relationship between air quality and weekly fill rates for short-acting beta agonists in three western states — California, Washington and Oregon — from July 5 to September 30. This analysis uses PM 2.5 (fine particulate matter pollution) data as a measure of air quality, which is the primary pollutant in fire smoke and can pose the most significant risk to a person’s health.
Fires, air quality, and inhaler fills
This year, California, Oregon, and Washington saw a large number of fires. California had over 9,000 fire incidents this year resulting in over 4 million burned acres, and Oregon had over 2,000 fires and over 1 million burned acres. Similarly, Washington suffered from 16 major fires and over 700,000 burned acres.
Most of these fires occurred between July and September, and during this time we observed increased fill rates for short-acting beta agonists (SABAs). On average, there was a 28% increase in fill rate for SABA drugs during weeks in which regions experienced poor air quality. The largest observable spike was in the first week in September, when most of the fires occurred.
Much of this increase in fills can be explained by the air quality in the regions near large fires. By the end of August, and well into September, we saw a steady increase in PM 2.5 levels for regions reporting poor air quality due to fires. And on September 13, particulate matter concentrations for regions with fires were three times as high as regions without fires. That day, while particulate matter concentration averaged 100 μg/m3 in areas with fires, which is considered very unhealthy, some regions saw PM 2.5 levels reaching well into 400 μg/m3. More on that below.
Overall, fills for SABA drugs tracked closely to air quality. In fact, on September 13, we saw the worst average air quality this summer, and the largest fill rate for short-acting inhalers.
Air quality, state by state
It’s clear that there is a strong relationship between fires, air quality, and fills for inhalers. But some areas suffered more than others. Regions in central California and Oregon saw dangerously poor air quality, which most certainly affected inhaler fills.
California
In California, the region with the highest PM 2.5 reported was in Mammoth Lakes, California, with concentration around 405 μg/m3. This region was surrounded by two of the largest fires, the Creek Fire and the SCU (Santa Clara Unit) Lightning Fire. Regions with poor air quality are highlighted on the map below (scroll over for zip code), and the fires are circled.
Oregon
Sisters, Oregon reported the highest PM 2.5 concentration in the state with 313 μg/m3. This region was particularly close to the Holiday Farm Fire and surrounded by the other three top fires. Regions with poor air quality are highlighted on the map below (scroll over for zip code), and the fires are circled.
Washington
For Washington, the regions near Spokane reported the highest PM 2.5 concentration of 221 μg/m3. This reporting area was closest to the Whitney Fire. Regions with poor air quality are highlighted on the map below (scroll over for zip code), and the fires are circled.
Health effects of fires, poor air quality, and smoke
The fine particles from the smoke can infiltrate deep into the lungs and cause several health problems, including burning eyes and runny nose, as well as aggravate chronic heart and lung diseases.
Poor air quality from fires can have compounding effects on those who live nearby, who may suffer from the elevated PM 2.5 levels. Some may have to seek care and be treated with SABA drugs for their breathing difficulties and symptoms. Those who already have asthma or lung disease will be even more at risk of having severe complications from exposure to poor air quality.
On top of that, those who have had long-term exposure to high PM 2.5 levels may be more at risk of dying from COVID-19 if they become infected with the virus. A study conducted at the Harvard T.H. Chan School of Public Health found that counties with higher historical PM 2.5 levels also saw higher county-level COVID-19 mortality rates. The study adjusted for other possible confounding variables; however, the researchers found that a small increase in long-term exposure to PM 2.5 leads to a large increase in the COVID-19 death rate.
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Co-contributors: Lauren Chase, Amanda Nguyen, PhD, Jeroen van Meijgaard, PhD, Diane Li, Jennifer Tran, PharmD, RPh
Methodology:
Effect of poor air quality on fill rate for short-acting beta agonists:
The effect of poor air quality was estimated using the following differences-in-differences model with reporting area and week fixed effects. The poor air quality indicator variable is equal to 1 when the weekly average PM2.5 concentration exceeds 55.4 µg/m3, which is the threshold for an unhealthy PM2.5 concentration.
ln(Fill rater, t) = β1(1 if poor air quality__r, t)+θr+δt+εr,t
where reporting area r∈{Albany, …, Willits}
and time t∈{week beginning 07/05/2020, …, week beginning 09/27/2020}
Supplemental table:
Air quality data:
Using the AirNow API at Airnow.org, we acquired historical daily peak air quality index (AQI) observations for PM2.5 from July 5, 2020, to September 30, 2020 in the states of California, Oregon, and Washington. Observations are given by reporting area as designated by the EPA, with each reporting area mapping to multiple zip codes near that area. The AQI was then converted into PM2.5 concentration using the AQI equation. Any AQI values above 500 were considered “beyond the index” and topcoded to an AQI of 500. Finally, daily values were aggregated into weekly averages by reporting area.
Fill rate:
Using a representative sample of U.S. prescription fills, we calculated the weekly share as the number of fills for short-acting beta agonists divided by the number of fills of all drugs, after removing drugs with a seasonality component in filling patterns. We excluded any fills in reporting areas that did not meet our claim count threshold. The weekly share was gathered on zip code level and then mapped to the corresponding reporting areas.
Short-acting beta agonists: albuterol, Accuneb, levalbuterol, Proair, Proventil, Ventolin, Xopenex, Xopenex HFA
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