Influence of meteorological condition during rainstorm periods on the ambient concentrations of fungi in Bangkok, Thailand

Meteorological conditions change substantially during rainstorms, potentially affecting ambient concentrations of fungal spores. Exposure to ambient fungal spores during rainstorm periods may result in adverse health outcome such as thunderstorm asthma and allergic symptoms. This study investigated the ambient concentrations of culturable fungi during rainstorms period in Bangkok, Thailand. Using a single-stage impactor, air samples were collected between October and November 2017, when Thailand was struck by three major tropical cyclones: Typhoon Khanun, Typhoon Damrey, and Typhoon Kirogi. Fungal colonies were counted and identified according to their morphology. Meteorological data were obtained from the Thai Meteorological Department. Multiple regression analysis, performed to determine the associations between fungal concentrations and meteorological parameters, revealed a mean fungal concentration of 1,230 ± 1,136 CFU/m³ (n = 60). Fungal concentrations increased before the rainstorm arrival and decreased during the downpour rain. The fungal genera Cladosporium sp., Penicillium sp., and Aspergillus sp. were commonly observed but less than nonsporulating fungi, which accounted for more than 68% of all colonies. Fungal concentrations were positively associated with meteorological parameters, namely temperature, relative humidity, and maximum wind speed (R² = 0.58, p < 0.05). Considerable changes in daily weather conditions during rainstorm periods strongly affected the fungal concentrations. Future studies should collect relevant hospital admission and more fungal monitoring data to determine the associations between fungal exposure during rainstorm periods and adverse outcomes.