South Africa's first pollen calendars show when hayfever season hits your city

Hayfever affects up to 30% of South Africans, but until now there was little local data on when pollen seasons start and end. The South African Pollen Monitoring Network has now produced the country's first five-year pollen calendars, covering seven cities. Grass is the main culprit everywhere. People living inland are hit hardest: in Bloemfontein and Kimberley, grass pollen seasons last about eight months, while Durban and Gqeberha see fewer than 100 days. Exotic garden trees add heavily to pollen levels in cities, from cypress in Cape Town to mulberry in Pretoria. The calendars could help doctors diagnose allergies and help sufferers start treatment early..By Trevor Hill, Andriantsilavo Hery Isandratana Razafimanantsoa*.For some South Africans, the beginning of the flower season is met not with the joys of spring but rather with a sniffy nose, itchy eyes and a cacophony of sneezing.In South Africa, allergic rhinitis (hayfever) affects an estimated 20% to 30% of the population – children and adults. Asthma affects around 20% of children and 10% of adults. Air pollution can worsen asthma and eczema symptoms and cause eczema.Most people recognise that pollen, despite being invisible to the naked eye, is a dominant airborne allergen driving conditions like hayfever. Sufferers are acutely aware that pollen in the air changes seasonally, depending on what is flowering.But South Africans still know too little about when pollen seasons begin and end, or how they differ across the country. This is because there’s been very little consistent, long-term pollen monitoring. Without local records showing when different plants release pollen, it’s hard for doctors to identify what is causing a patient’s allergy. People with allergies are also left guessing when to start taking medicines that could prevent their symptoms.Now, a pioneering scientific initiative is changing that. The South African Pollen Monitoring Network, set up seven years ago, sourced equipment and built research teams in different cities. The network has now produced South Africa’s first five-year pollen calendars for several different natural regions. These calendars show which plants release pollen in each region, when they release it and how pollen levels change during the year.Previously, pollen was measured in only a few African cities, and researchers used different methods, making it difficult to compare the results. The new network uses the same method to collect pollen from the air at all its sites. However, many pollen grains look so similar that scientists can identify only the plant family, such as grasses, rather than the exact species.The network covered inland grassland sites in Johannesburg and Bloemfontein, and savanna sites in Pretoria and Kimberley. Its coastal sites represented fynbos in Cape Town, the Indian Ocean coastal belt in Durban and Albany thicket in Gqeberha..We found that grass was the most common pollen everywhere, Bloemfontein had the highest overall pollen levels, Johannesburg had the most tree pollen, and Kimberley the most grass pollen.This research is important because these calendars could help doctors diagnose and manage allergies and support warnings about periods of high pollen exposure.The pollen causing allergies in inland cities.Over five years, South African Pollen Monitoring Network researchers identified 103 types of pollen across seven South African cities. Grass produced the most pollen and was the main cause of pollen allergies. Inland cities had much higher pollen levels than coastal cities, and their grass pollen seasons lasted for more than 200 days a year.Bloemfontein (grassland biome): highest total amount of pollen recorded over a year, mainly because of its high levels of grass and tree pollen. Grass released pollen for an average of 246 days each year – about eight months.Kimberley (savanna biome): highest average concentration of grass pollen, with an open, grassy landscape and a grass season lasting, on average, 247 days a year.Johannesburg (grassland biome): highest average tree pollen, probably due to its large “urban forest” of planted exotic trees.Pretoria (savanna biome): high tree pollen counts, dominated by the exotic Morus (mulberry) tree, which contributed 25% to the total pollen catch.Coastal citiesIn contrast to the inland cities, coastal cities recorded lower overall pollen loads and shorter grass seasons, often under 100 days a year. This difference is likely due to coastal rainfall washing the pollen out of the atmosphere, combined with strong coastal winds..Cape Town (fynbos biome): the longest tree pollen season in the country, lasting 297 days a year, starting early in July. The pollen profile is dominated by exotic trees, with Cupressaceae (cypress) accounting for 30% of the five-year average, followed by Myrtaceae (eucalyptus) at 11%, and Pinus (pine) at 9%.Durban (Indian Ocean coastal belt): low overall pollen catch, with the shortest grass season in the study, lasting just 71 days and starting late in summer.Gqeberha (Albany thicket biome): lowest overall annual pollen load among all seven cities, alongside the shortest tree (116 days) and grass (92 days) seasons.Climate change impact on pollen allergiesBetween 2019-2021 and 2022-2024, pollen levels fell across most regions. Grass pollen nearly halved, while tree pollen doubled in inland cities. Researchers now need to examine whether rainfall, weather, flowering seasons or changes in land use caused this shift.Climate change may play a part by changing pollen levels and seasons. It can also increase the risk of “thunderstorm asthma”. During some storms, moisture bursts grass pollen into tiny pieces that winds push towards the ground. When inhaled, they can cause sudden and dangerous asthma attacks.What this means for allergic patientsFor people suffering from hay fever or asthma, calendars tailored to South Africa’s specific regions can act as an early warning system. Knowing exactly when pollen season starts lets patients begin preventive treatments, such as antihistamines or nasal sprays, before their symptoms start.The new data revealed surprising allergy triggers. For instance, birch tree pollen, a major cause of hay fever in the northern hemisphere, was detected across South Africa where it is an ornamental, non-indigenous tree planted in gardens..Read more:. Climate change is making allergy season longer, more intense: Lisa Jarvis.The general public may underestimate the dominant role of exotic trees in driving pollen load in big cities like Cape Town, Johannesburg and Pretoria. This finding should feed into decisions about what to plant.What needs to happen nextFive years of pollen data show why year-round monitoring matters for public health. Researchers want to extend monitoring into rural areas and include pollen warnings in the national health system. They also hope to use DNA testing to identify allergy-causing plants that look identical under a microscope.For now, the calendars help South Africans see which pollen is in the air, when levels are highest and when they may need to take precautions..*Trevor Hill: Professor, Department of Geography, University of KwaZulu-Natal*Andriantsilavo Hery Isandratana Razafimanantsoa: Postdoctoral Research Fellow at the UCT Lung Institute, University of Cape Town.This article was first published by The Conversation and is republished with permission..Sign up for your early morning brew of the BizNews Insider to keep you up to speed with the content that matters. 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South Africa's first pollen calendars show when hayfever season hits your city

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