title: Hourly differences in air pollution on the risk of asthma exacerbation.
abstract: We investigated the association between hourly differences in air pollution and asthma exacerbation in Korea using asthma-related emergency department data and verified seasonality and demographic modifiers with an hourly temporal resolution. We applied time-stratified case-crossover adjusted for weather and influenza; the lag was stratified as 1-6, 7-12, 13-18, 19-24, 25-48, and 49-72 h. Odds ratios (95% confidence interval) per interquartile range increase were 1.05 (1.00-1.11) after 1-6 h for PM10-2.5 and 1.10 (1.04-1.16) after 19-24 h for O3. Effect size was 1.14 (1.06-1.22) at a 1-6 h lag in spring for PM10-2.5, and 1.25 (1.03-1.51) at a 25-48 h lag in winter for O3. O3 effects were age- and low socio-economic status-modified at a 7-12 h lag [1.25 (1.04-1.51)]. Increased PM10-2.5 and O3 increased the risk of asthma exacerbation; the effect of PM10-2.5 was most immediate.
authors.affiliation: Department of Biostatistics and Epidemiology, Graduate School of Public Health, Seoul National University, Seoul, South Korea. Electronic address: kimjayeun@gmail.com.
authors.forename: Jayeun
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Biostatistics and Epidemiology, Graduate School of Public Health, Seoul National University, Seoul, South Korea; Institute of Health and Environment, Seoul National University, Seoul, South Korea. Electronic address: hokim@snu.ac.kr.
authors.forename: Ho
authors.initials: H
authors.lastname: Kim
authors.affiliation: Seoul Metropolitan Government Research Institute of Public Health and Environment, Seoul, South Korea. Electronic address: jungk719@seoul.go.kr.
authors.forename: Jung
authors.initials: J
authors.lastname: Kweon
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000032:analysis; D001249:Asthma / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007251:Influenza, Human / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D010126:Ozone / Q000032:analysis*; D052638:Particulate Matter / Q000032:analysis*; D056910:Republic of Korea / Q000453:epidemiology; D012306:Risk; D012621:Seasons; D012923:Social Class; D013997:Time Factors; D014887:Weather; D055815:Young Adult
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D010126:Ozone
keywords: Air pollution; Asthma; Case-crossover; Effect modification; Emergency department