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.
Extremely low levels of pollen and fungal spores were seen during the recent sampling period. Low levels for trees, grasses and weeds were present in the atmosphere. The fungal spore levels are usually low in January, but the drought has further depressed the concentrations.
The tree, grass and weed pollen concentrations were all low during the past sampling week. Rain at the end of the preceding sampling week impacted on the fungal spores and moderate levels of Alternaria were seen. The fungal spore load was generally low.
Pollen concentrations in the tree, grass and weed categories have been consistently low. Fungal spore levels have been generally low but increased after rain on Sunday 7 January. Cladosporium and Alternaria levels increased and while these concentrations did not breach the significant threshold, the small peaks should be noted.
The abrupt change of weather that the Cape has been experiencing has favoured the increase in fungal spores. Moist, cool days followed by warm dry weather has seen sharp increases in Alternaria, and Cladosporium concentrations. Grasses are low on days of rain becoming moderate on warm days. Weed levels are low, but Chenopodiaceae (fat hen) erica, English Plantain and dandelion are pollinating now. Tree levels have decreased to low levels but Cypress, pine, gum, olive, plane and oak are still present in the atmosphere in low concentrations.
The recent cold and rainy weather reduced the grass counts, but moderate grass concentrations were seen. Tree and weed pollen counts were low. Sunshine after rain increased fungal spore counts and Cladosporium increased but remained below the significant threshold. Alternaria counts were high. For further information on pollen and allergies see: www.lunginstitute.co.za (Allergy and Immunology Unit)
Rain during the last sampling week has removed pollen and fungal spores from the air. This should bring relief to hay fever sufferers. The grass counts are moderate. Tree pollen concentrations are waning, but moderate levels of olive are present in the atmosphere. Weed pollen levels remain low. Fungal spore levels are low but have increased and the Alternaria level is close to the threshold level.