Evaluation of the impact of exposure to air pollution change on variation of lung function among refractory asthmatics in urban areas of South Korea

摘要

In this study, we examined the association of variation of lung function (FEV1/FVC) with the change of air pollution level among refractory asthmatics living in metropolitan cities of South Korea, Seoul, Incheon or Bucheon. We retrospectively studied the spirometry data of adult patients, aged 19-87 years, who had been registered since 2005. All subjects were followed for a minimum of 2 years in an asthma cohort from the Genome Research Center for Allergy and Respiratory Diseases, Soonchunhyang University Bucheon Hospital, South Korea. The diagnosis of asthma was based on the Global Initiative for Asthma (GINA) guidelines. In our study, we included only the 82 patients living in the metropolitan city of Seoul, Incheon or Bucheon, South Korea, who presented at the Soonchunhyang Hospital between 2005 and 2015 with multiple episodes of exacerbations. Our final data comprised 2310 episodes from 214 RA nonsmoking patients whose ratio of FEV1 divided by FVC was < 80%. We constrained an "episode" to have a frequency no greater than one visit per month to avoid attributing follow-up visits to new independent episodes. Air pollution measurements were obtained from the national ambient monitoring station located closest to each patient's home address. Multilevel model analyses were conducted using the SAS 9.1 package. The data stratified by season and smoking status showed that in multi-pollutant models with smoking RA patients, in winter, a 1°C decrease in ambient temperature and a 1 ppb increase in SO2 concentration significantly decreased lung function (FEV1/FVC) on Lag3 and Lag4 after controlling for other explanatory variables: 0.3 % for temperature and 2.0% for SO2. Exposure to temperature drops and increased sulfur dioxide concentrations are positively associated with decrease of lung function during winter with 3 or 4 day lags.