Fern spore and pollen airspora profile of Singapore

Monitoring atmospheric fern spore and pollen loads in Singapore was initiated in June 1990. Aside from the more numerous fungal spores, fern spores and pollen grains made up 6.2–8.6% and 4.4–5.4% of the total airspora sampled, respectively. The most frequently encountered fern spores, in descending order, were those of Nephrolepis auriculata, Dicranopteris linearis, Stenochlaena palustris, Asplenium nidus, Pteridium aquilinum, and Dicranopteris curranii. For pollen grains, the most frequently encountered, in descending order, were Elaeis guineensis, Casuarina equisetifolia, Acacia auriculiformis, Kyllingia polyphylla, Podocarpus, and Poaceae pollen grains. Seasonal patterns for individual fern spore or pollen types were discernible despite the relatively uniform tropical climate in Singapore. The fern spore and pollen calendar for the period 1991–1995 was compared to that of 2005–2006 as a follow-up study to keep abreast with the rapidly changing landscape of Singapore. Diurnal patterns showing a late morning to afternoon peak period were seen in fern spores, while the peak period was in the morning for pollen types studied with the exception to oil palm pollen. Additionally, association between fern spore and pollen counts and local meteorological conditions were also analyzed and found to be highly correlated. This study has thus identified the fern spores and pollen airspora components, and determined the calendars, as well as diurnal profiles of the Singapore airspora and provides invaluable information for allergy studies by highlighting the trigger sources present in the environment.