Seasonal variation of airborne allergenic fungal spores in ambient PM₁₀—a study in Guwahati, the largest city of north-east India

Fungal spores in ambient particulate matter (PM) is one of the major constituents which can adversely affect human health. For the first time, an investigation was conducted for 1 year at a residential region in north-east India to study the seasonal variation of PM₁₀-associated fungal spore concentration and their diversity. Using fine particulate sampler, samples were collected at 12 h intervals for 1 week of every month during July 2016–June 2017. Twelve-hour averaged PM₁₀ concentration was 79.74 μg/m³ and 103.47 μg/m³ during day and night time, respectively. Fungal spore concentration was 126 (54–294) CFU/m³ during day time and 107 (55 to 161) CFU/m³ during night time. Seven individual genera of fungal spores, namely Aspergillus, Penicillium, Cladosporium, Fusarium, Curvularia, Rhizopus, and Non-sporing isolates, were identified. Strong correlations between the Cladosporium and Penicillium (R = 0.83) and Cladosporium and Aspergillus (R = 0.82) were observed, which are well-known asthma allergens. Penicillium (30%), Fusarium (41%), and Aspergillus (25%) were the dominant fungi species in winter, monsoon, and summer seasons, respectively. Fungal spore concentrations peaked during summer and were least during monsoon. Fungal concentrations were negatively correlated with precipitation (R = − 0.25). Fungal counts had more significant positive correlation with temperature in non-rainy samples (R = 0.80), compared to negligible correlation (R = − 0.16) in all samples.