Patterns of asthma symptoms and perceptions of harm from seasonal atmospheric events in rural western Montana

To characterize the frequency of and relationship between self-reported asthma symptoms and physician-diagnosed asthma, identify seasons associated with heightened symptoms, and describe the influence of seasonal atmospheric events and ambient environmental factors on asthma symptoms and perceptions of harm, a seven-county region of Western Montana was surveyed, utilizing a two-stage sampling method. Respondents were queried concerning asthma-related history, symptoms, and environmental concerns. Of 2,790 respondents, 12% reported physician-diagnosed asthma. Eighteen percent reported one or more and 9% reported two or more asthma-related symptoms. Over 70% of asthmatics reported worsened asthma symptoms during wildland-fire smoke exposure. Of those reporting summer as the season they experienced the greatest breathing problems, 81% reported breathing problems from wildland-fire smoke (p < 0.01). Of those reporting worsened symptoms in fall or winter, 61% reported breathing problems during winter inversions (p < 0.001).