We are in the months of the year with the lowest pollen concentrations in Cape Town. Despite this, Cupressus pollen is appearing in the atmosphere in low concentrations as it begins its pollen release cycle. Fungal spores soar on sunny days following rain, but are composed largely of basidispores (includes mushrooms) and ascospores.
Fungal spore levels are moderate as ascospores increase after rain. Small spikes for basidiospores (includes mushrooms) and Cladosporium were seen during the past week. Tree and grass pollen concentrations were low but moderate concentrations were observed again for weed pollen as Parietaria completed its pollen release cycle.
Parietaria is a weed from the family Urticaceae. Parietaria concentrations are steadily rising in Cape Town. Current heavy rain will have washed this pollen from the air, but it will reach its highest concentrations in the last week of May and decrease in early June. Tree and grass pollen concentrations were low. Fungal spore levels were similarly low, despite small peak on sunny days for basidiospores, ascospores and Cladosporium.
Frequent rain during the recent sampling period removed pollen and fungal spores from the air. On sunny days following rain, ascospores, basidiospores and Cladosporium concentrations increased. The weed, Parietaria is flowering and moderate concentrations were seen on sunny days.
The autumn weather has set in with intermittent rain, longer nights and some clear, calm days. Pollen concentrations in the categories of trees, grasses and are all low, but some low concentrations for grasses and weeds such as Myrica were seen. Fungal spores are moderate as basidiospore (mushroom) appear in the atmosphere in response to the cooler temperatures and increased humidity.
Fungal spore concentrations increased in response to a little rain and cooler temperatures with early morning dew. Cladosporium increased but no significant concentrations were recorded. Alternaria levels were moderate. Weed levels are increasing as we move into autumn and Myricaceae concentrations are increasing. Tree and grass pollen concentrations were low.
Pollen and fungal spore concentrations reverted to their earlier low levels as no rain fell during the sampling period ending 12 March. After the rain that occurred yesterday in some areas of Cape Town, fungal spore levels are expected to increase, especially Alternaria, Cladosporium and ascospores.
The recent rain increased fungal spore production. Alternaria and Cladosporium levels increased sharply to allergenic levels. Tree and grass pollen levels are low, but week pollen is increasing.
The rain during this sampling week affected the bioaerosols by sharply increasing the concentrations of fungal spores and pollen in the atmosphere. Significant Alternaria concentrations were seen and Epicoccum, Rusts ascospores and Cladopsorium concentrations increased. Moderate concentrations were consistently seen for Chenopod, or goosefoot weed.
Fungal spore levels will probably remain high following yesterday’s thunderstorm. Weed pollen will increase as autumn approaches.
The drought conditions have resulted in very dry air with low pollen and fungal spore concentrations. In some areas of Cape Town, light rain has fallen at times and there has been an immediate response in the Alternaria and Cladosporium concentrations. Cladosporium spores are scant, despite increases but Alternaria is a dry air spore and spores quickly after rain. The Alternaria concentrations at the Observatory sampling site this week were just below the significant level.