Patients With Asthma, Comorbid Allergy Are More Susceptible to PM2.5 and Ozone

air pollution
Investigators used electronic medical records to examine the relationship between ambient PM2.5 and ozone concentrations with acute asthma visits (office, urgent, emergency, and hospitalization).

Particulate matter ≤2.5 μm in diameter (PM2.5) and ozone exert negative effects on patients with asthma, with even greater negative effects observed in patients with asthma and a comorbid allergy. This is according to study results published in the Journal of Exposure Science & Environmental Epidemiology.

Researchers reviewed electronic medical records of children and adults with 1 or more diagnosed asthma visit at a single health facility from January 2011 to June 2017. It used medical records to identify patients with asthma with an allergic comorbidity (n=24,337) and without an allergic comorbidity (n=25,495). A centralized monitor provided data on daily 24-hour average PM2.5, 8-hour maximum ozone, and mean temperature in the study area.

During the study period, the average daily 24-hour PM2.5 concentration was 7.1 μg/m3. There were significant differences in the adjusted odds ratios (aORs) for the 3-day moving average PM2.5 (P =.05) comparing visits in patients with asthma and an allergic comorbidity (aOR 1.10; 95% CI, 1.07-1.13) vs visits in patients with asthma but without an allergic comorbidity (aOR 1.05; 95% CI, 1.02-1.09).

There were also significant differences in the aORs for 3-day moving average ozone (P =.04) comparing visits for patients with asthma and an allergic comorbidity (aOR, 1.08; 95% CI, 1.02-1.14) vs visits in patients with asthma but without an allergic comorbidity (aOR, 1.00; 95% CI, 0.98-1.05). Patients with asthma and an allergic comorbidity also had higher aORs for air pollution and asthma visits vs patients with asthma but without an allergic comorbidity.

A limitation of the study was the inability of the researchers to identify allergic comorbidities directly, which may have resulted in misclassification of some patients.

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The researchers wrote that if patients with asthma and “with the allergic phenotype are more susceptible to air pollution exposures, awareness of this relationship can be integrated into behavioral management.”


Rosenquist NA, Metcalf WJ, Ryu SY, et al. Acute associations between PM2.5 and ozone concentrations and asthma exacerbations among patients with and without allergic comorbidities [published online February 24, 2020]. J Expo Sci Environ Epidemiol. doi:10.1038/s41370-020-0213-7