Association of the daily ratio of FEV1 to FVC with the real-time exposure level to indoor PM2.5 and C02 after controlling for other risk factors in adult non-smoking refractory asthmatics in urban areas of South Korea: Results from Environmental Health St

摘要

Background As acute exacerbations of refractory asthma (RA) can be fatal, it is important to recognize the risk factors with consideration that the immune system may undergo continuing change by age among adults and adult asthmatics tend to stay indoor. We evaluated the associations between variation in daily exposure levels to indoor air quality, and daily changes in lung function (FEV1/FVC ratio) of RA sufferers, after controlling for total immunoglobulin E (IgE) levels, smoking status, and seasonality. Methods We analyzed sensing technology based spirometry data from refractory asthmatics whose mean FEV1/FVC ratio is lower than < 80%, lived in Seoul or Kyunggi Province, South Korea , and attended hospital between 2016 and 2017 with multiple exacerbations. We constructed mixed model using the data clustered within each patient. Results We analysed 1100 episodes data relating to 25 never-smoking patients. After adjusting for sex, age, body mass index (BMI), and total IgE level, a unit increase in concentration of particles <2.5 urn (PM2.5), or C02 concentration on Lag 0, reduced the FEV1/FVC ratio by 0.1% (95% confidence interval [CI]: 0.0-0.4%). Patients living in house with high damp scores (3 and 4) showed lower ratio than the others (1 and 2). Conclusions This study demonstrated that reduction in pulmonary function in adult asthma patients were potentially associated with acute exposure to increased indoor PM2.5, C02 and damp levels with irrespective to total IgE level.