Spring has arrived and the pollen season is now in full swing. Grass and tree pollen levels are currently high. We know this, not only because seasonal hay fever sufferers are sneezing, but because in Cape Town we have weekly pollen monitoring. Pollen is identified and counted in the research laboratory of the University of Cape Town’s Lung Institute and posted on the website. The pollen count is also updated each week at www.pollensa.co.za. UCT has been monitoring pollen in different areas of Cape Town for more than 20 years. If there is one thing that we have learnt is that each pollen season is different! The pollen count changes each week and every year, so that it is very important to monitor pollen for each new season, rather than using pollen counts from previous years because weather patterns, like rain, wind, temperature and humidity, directly affect pollen in the air.
Figure 1 below shows how the grass count varies with each year in response to weather patterns.
Grass counts decrease in drought years and increase after good rainfall.
Grass pollen counts started to increase from mid-September this year and high grass pollen counts are currently being posted. The start of the grass pollen season changes every year and grass pollen levels usually continue through to January, but high counts have been recorded as late as May. This is because there are many grass species that flower at different times of the year. Grasses flower according to daylight hours. Some begin to flower when day/night hours are equal lengths, while other grass species flower when daylight exceeds darkness.
Weed pollen is not as significant in South Africa as it is in North America and Europe where the major weed, ragweed, is found. However, large areas of South Africa have not been monitored, so it is possible that weeds in some areas do produce high weed pollen counts.
Not all pollen triggers symptoms of seasonal allergy. It is the wind pollinated plants that are allergenic as they release large numbers of pollen grains into the atmosphere. Brightly coloured flowers and flowering trees are usually insect pollinated and the pollen from these plants seldom triggers allergic reactions. Low pollen counts from insect pollinated plants are found in the atmosphere.
There are numerous websites that forecast pollen and fungal spore levels in the air in South African cities, but they are largely ’fake pollen counts’ and may misinform the public. Many of these websites make inaccurate predictions or include plants like ragweed that are not found in abundance in South Africa and have not so far been seen in Cape Town pollen counts. There is an urgent need to expand pollen monitoring to the other major cities in South Africa, to provide accurate up to date information. The UCT Lung institute is looking for interested commercial sponsors to assist in setting up monitoring in Johannesburg, Pretoria, Durban and Bloemfontein. If you have ideas or are interested in supporting this valuable initiative please contact Prof Jonny Peter at Jonny.Peter@uct.ac.za.
There are a number of clinical benefits for allergy sufferers and their doctors, to ascertain accurate, up to date pollen monitoring. The first is the identification of the offending pollen that is triggering symptoms. Is it a grass or a tree pollen? If so which one? Knowing what you are breathing in can help direct allergy testing to find the culprit and save costs. Second, up to date counts allow patients with known symptoms to schedule their outdoor activities, thus avoiding certain weeks in the summer for outdoor picnics for instance, or ensuring adequate antihistamines are packed. Athletes with pollen allergies can better plan training schedules with good monitoring.
The Allergy Foundation of South Africa supports the call for national pollen monitoring and also provides allergy sufferers with updated pollen information at www.allergyfoundation.co.za. For more information on pollen allergy see http://www.allergyfoundation.co.za/patient-information/en/allergens/pollen-allergy/