title: Particulate matter modifies the association between airborne pollen and daily medical consultations for pollinosis in Tokyo.
abstract: Pollen from Japanese cedar (sugi) and cypress (hinoki) trees is responsible for the growing prevalence of allergic rhinitis, especially pollinosis in Japan. Previous studies have suggested that air pollutants enhance the allergic response to pollen in susceptible individuals. We conducted a time-stratified case-crossover study to examine the potential modifying effects of PM2.5 and suspended particulate matter (SPM) on the association between pollen concentration and daily consultations for pollinosis. A total of 11,713 daily pollinosis cases (International Classification of Diseases, ICD-10, J30.1) from January to May, 2001-2011, were obtained from a clinic in Chiyoda, Tokyo. Daily pollen counts and the daily mean values of air pollutants (PM2.5, SPM, SO2, NO2, CO, and O3) were collected from monitoring stations across Tokyo. The effects of pollen were stratified by the level of PM2.5 and SPM to examine the interaction effect of pollen and particulate pollutants. We found a statistically significant interaction between pollen concentration and PM2.5/SPM. On days with a high level of PM2.5 (>95th percentile), an interquartile increase in the mean cumulative pollen count (an average of 28 pollen grains per cm(2) during lag-days 0 to 5) corresponded to a 10.30% (95%CI: 8.48%-12.16%) increase in daily new pollinosis cases, compared to 8.04% (95%CI: 7.28%-8.81%) on days with a moderate level of PM2.5 (5th-95th percentile). This interaction persisted when different percentile cut-offs were used and was robust to the inclusion of other air pollutants. A similar interaction pattern was observed between SPM and pollen when a less extreme cut-off for SPM was used to stratify the effect of pollen. Our study showed the acute effect of pollen was greater when the concentration of air particulate pollutant, specifically PM2.5 and SPM, was higher. These findings are consistent with the notion that particulate air pollution may act as an adjuvant that promotes allergic disease (i.e. pollinosis).
authors.affiliation: Department of Human Ecology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; Department of Anthropology, University of Washington, Box 353100, Seattle, WA 98195-3100, USA. Electronic address: moe@humeco.m.u-tokyo.ac.jp.
authors.forename: Shoko
authors.initials: S
authors.lastname: Konishi
authors.affiliation: Environmental Epidemiology Section, Center for Environmental Health Sciences, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki, 305-8506, Japan.
authors.forename: Chris Fook Sheng
authors.initials: CF
authors.lastname: Ng
authors.affiliation: Department of Human Ecology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Andrew
authors.initials: A
authors.lastname: Stickley
authors.affiliation: Nishihata Ear, Nose and Throat Clinic, 2-10-1 Yuraku-cho, Chiyoda-ku, Tokyo, 100-0006, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Nishihata
authors.affiliation: Department of Human Ecology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Chisa
authors.initials: C
authors.lastname: Shinsugi
authors.affiliation: Environmental Epidemiology Section, Center for Environmental Health Sciences, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki, 305-8506, Japan.
authors.forename: Kayo
authors.initials: K
authors.lastname: Ueda
authors.affiliation: Center for Regional Environmental Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba-City, Ibaraki 305-8506, Japan.
authors.forename: Akinori
authors.initials: A
authors.lastname: Takami
authors.affiliation: Department of Human Ecology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Chiho
authors.initials: C
authors.lastname: Watanabe
mesh_terms: D000328:Adult; D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000706:statistics & numerical data; D000485:Allergens / Q000032:analysis*; D004784:Environmental Monitoring; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D052638:Particulate Matter / Q000032:analysis*; D011058:Pollen; D012017:Referral and Consultation / Q000706:statistics & numerical data; D006255:Rhinitis, Allergic, Seasonal / Q000453:epidemiology*
chemical_list: D000393:Air Pollutants; D000485:Allergens; D052638:Particulate Matter
keywords: Air pollution; Allergy; Particulate matter; Pollen; Pollinosis