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Abstract Air pollution is a pervasive environmental health hazard with the potential to worsen respiratory health outcomes, including asthma exacerbations. The impact of PM2.5 on asthma exacerbations among rural populations is not well understood. Our analysis used a retrospective, time-stratified, case-crossover study design to examine the relationship between PM2.5 and asthma exacerbations. We included asthma exacerbations that occurred January 1, 2019-June 30, 2022, among residents of seven rural counties in Wisconsin with a PM2.5 air monitor. We also used PM2.5 data collected by the Wisconsin Department of Natural Resources and weather data available from the National Oceanic and Atmospheric Administration (NOAA). Further, we used conditional logistic regression to assess the association between asthma exacerbations and lagged PM2.5 levels, adjusting for maximum daily temperature. We found PM2.5 levels (µg/m3) 2 days prior to exacerbation were significantly associated with asthma exacerbations (hazard ratio 1.184; 95% confidence interval [1.051, 1.344]). Our study demonstrated an increased hazard of asthma exacerbations with higher levels of PM2.5 in rural populations. These findings highlight the need for further research and efforts to mitigate the effects of air pollution in rural areas.
Keywords: asthma, respiratory health, air pollution, PM2.5, rural health
Introduction
Asthma is a prevalent chronic lung disease that affects approximately 1 in 10 children (Centers for Disease Control and Prevention [CDC], 20234) and 1 in 7 adults in Wisconsin (CDC, 2023b). Asthma symptoms can be triggered by tobacco smoke, dust mites, pests, mold, pets, and outdoor air pollution (CDC, 2024). Outdoor air pollution varies by geography (Strosnider et al., 2017) and is influenced by seasonal weather patterns (Winquist et al., 2014). PM, is one of the most ubiquitous pollutants and has been shown to exacerbate asthma symptoms. Multiple epidemiological studies have demonstrated that PM, , levels are positively correlated with asthma symptoms (Berhane et al., 2016), emergency department visits (Romieu et al., 1996), hospitalizations (Zheng et al., 2015), and mortality (Atkinson et al., 2014).
Our studys aim was to investigate the association between PM, , and asthma exacerbations in rural areas of Wisconsin because most previous studies have focused on urban centers. Assessing time-varying pollutant exposures on asthma exacerbations can be challenging, however, particularly when working with administrative data...