Distributions and Characteristics of Ambient Fungal Spores and Their Effects on Asthma Attack

Background and Objective：The prevalence of asthma is increasing in many countries worldwide, including Taiwan. Fungal sensitization is an important risk factor for severe asthma, and also plays an important role in asthma seasonality. Comparing to the enor-mous diversity of the Fungal Kingdom, current knowledge on fungal allergy is very limited. Inadequate standardization of fungal extract used in skin and specific immuno-globulin E test further hamper the clinical awareness of fungal sensitization and lead to a severe underestimation of the prevalence of mold allergy. Fungal spores are the most common component being evaluated in epidemiological study. The study aimed to in-vestigate distributions and characteristics of ambient fungal spores, the relationships between ambient fungal levels and environmental factors and the correlation of temporal trends between fungal spore concentrations and emergency room visits for asthma.
Method：We have completed documenting ambient fungal spores from April to De-cember 2013 on the roof of Gutting Elementary School near an EPA air pollution moni-toring station. By using the Burkard seven-day volumetric spore trap to monitor the lev-els of ambient fungal spores, we investigated characteristics of ambient fungal spores and the health effects to human. Melinex tape was mounted on microscope slide with 10％ Mowiol and stained with glycerin jelly. Samples were identified under microscope at a 800x magnification using the longitudinal traverse method to obtain average daily concentrations (spores m-3). Complete daily meteorological data were retrieved from Central Weather Bureau-Taipei station. Daily air pollutants were retrieved from Taiwan Environmental Protection Administration monitoring station-Gutting station. Emergency room visits for asthma were retrieved from National Taiwan University Hospital (NTUH). We used descriptive statistics to present composition, distributions and tem-poral variation of ambient fungi. Fungal categories were grouped into three groups by principal component analysis. After using simple linear regression to get the variables significantly associated with fungal concentrations, put them into multiple regression to examine the relationships between ambient fungal spores and environmental factors. A time-stratified approach for the case-crossover technique and a conditional logistic re-gression were used to evaluate the associations between asthma-related emergency room visits and the levels of airborne fungal spores.
Result：A total of 275 samples was examined in this study. The most prevalent fungi were ascospores, basidiospores, Aspergillus/Penicillium, Cladosporium, smuts, Periconia, Fusarium and Arthrinium, which were present in more than 70% of the samples. In general, many fungal spores showed seasonal patterns during the study period. By multiple regression analysis, we found that most of fungal species were significantly positively associated with temperature and negatively associated with wind speed. Daily emergency room visits for asthma attack in National Taiwan University Hospital were 1.8 cases/day. After adjusting some confounders, asthma-related emergency visits in children aged from 5 to 15 years old were positively related to ascospores by conditional logistic regression (OR = 1.45; 95% CI = 1.15 to 4.57, for per IQR increment of 1223 spores/m3).
Conclusion：The most prevalent fungal spores in Taipei were ascospores, basidiospores, Aspergillus/Penicillium, Cladosporium. Meteorological factors and air pollutants ap-peared to affect ambient levels of fungal spores. High ambient levels of fungal spores might be related to emergency room visits due to asthma in children.