Hooray for spring. The mornings are warmer, the days are longer, the birds are singing and the flowers are blooming. But it’s also the time of year for runny noses, itchy eyes and sneezing fits. So while some of us are heading out for picnics to enjoy the gorgeous blossoms and watch those adorable ducklings do laps, hayfever sufferers are racing to their nearest pharmacy to stock up on tissues, antihistamines and nasal spray. Otherwise known as seasonal allergic rhinitis, hayfever affects about 15 per cent of Australians. But is spring really the worst time for hayfever across Australia? Is it the wattle? Not necessarily, says Associate Professor Janet Davies, from Queensland University of Technology’s School of Biomedical Sciences. Many of us associate hayfever with pollen from trees that come into flower in late winter and early spring (we’re looking at you wattle). But wattle may be unfairly maligned in the allergy blame game, Professor Davies says. She says allergy tests rarely confirm wattle is what sets off hayfever for most people. What happens to wattle pollen when it leaves the wattle flowers doesn’t support the notion either – it’s too heavy to travel very far. “We see those beautiful trees in flower and then when you look under those trees you will see a carpet of yellow, because the wattle pollen is very heavy and it just falls down essentially,” she says. On the other hand, grass pollen our most common outdoor airborne allergen doesn’t fall straight down; it gets carried on wind and can travel vast differences. And grasses flower at different times of the year in different parts of the country. So what’s pollen? Pollen is the microscopic grains produced by the male parts of the plant when it flowers. These need to be carried to the female parts of the plant, in order to reproduce. Pollen grains are typically spread by birds, bees or wind. Davies says flowering plants, which are more visually interesting to birds, bees and insects, tend to produce less pollen and the pollen needs to be carried directly from one plant to another. Other plants, including grasses, rely on wind to spread their pollen, and these tend to produce larger amounts of pollen that can travel vast distances. The Australasian Society of Clinical Immunology and Allergy says plants producing windborne pollen are a more significant cause of hayfever, and can affect people who are a long way from the source. “We don’t have a uniform pollen season,” says Professor Davies, whose research focuses on grass pollen allergies. “We have different types of grasses in different places [within Australia] and they have different drivers for production of the pollen in the air.” So if you live in south-eastern parts of the country, you may find you are sneezing at different times of the year to your cousins in Queensland, Northern Territory or Western Australia. Temperate grasses, especially ryegrass, are the most common causes of hayfever in New South Wales, ACT, Victoria, parts of Western Australia and Tasmania, and these tend to pollinate in late spring. “Ryegrass is the predominant grass pollen for patients who have allergies in Melbourne, for instance, but the further south you go, the later the start of the season. Tasmania will have a later pollen season, a later start and season peak, than Sydney or Melbourne.” Head to the northern parts of Australia and you’re more likely to find sub-tropical grasses, including Bermuda grass, Bahia grass or Johnson grass, and the peak pollen season for these can vary considerably. In Darwin, pollen peaks during the dry season in May and June, while Brisbane’s peak pollen season starts in January. “They can [create] a prolonged grass pollen season; into January, February, March and April. In fact, in Brisbane for the last three years, February has been the peak [time for] grass pollen in the air.” If you happen to live in a place that has both types of grasses Adelaide, Canberra and Sydney then you’re looking at more than one peak in grass pollen. One is when the temperate grasses flower in spring, then other peaks occur when the subtropical grasses have their turn in summer and early autumn. As well, these grasses are all around us in our cities and towns and planted for feed in rural areas. For instance, “Bermuda grass, which is sometimes called couch grass, is used in courting, ovals and lawns and golf courses”. So while you can reduce the amount of grass pollen you’re exposed to by not letting your lawn go to seed, “you can’t necessarily mow the whole council verge or your neighbours place or the wasteland beside the railway track or stop pollen blown on the wind from other places”. Professor Davies has been leading a team of researchers who are building the first national Pollen Monitoring Network (AusPollen) which will provide daily pollen counts for several of Australia’s capital cities. (While Melbourne and Sydney have had a long-running pollen count on 1 October, Melbourne, Canberra and Sydney will start counting with the network. Brisbane will also be on board within months.) The purpose of the pollen count is to help those with hayfever be able to identify days when the pollen count is high. “This will allow us to count the pollen in the air and give a short-term forecast of what the likely pollen count will be in the next one to seven days,” Professor Davies says. “[So they may decide] maybe today is the day to be aware and pay attention to how I am feeling and take some preventative action.” Sufferers may for instance choose to remain indoors in the first half of the day, as pollen is released in the morning. But Professors Davies points out pollen can travel vast distances on winds. “The main source of the pollen, we believe, is outside the urban areas. So even if it is released early in the morning, it’s picked up by the wind and delivered to people in cities throughout the day.” Taking over-the-counter antihistamines or using a nasal spray is another option for many suffers. “But if you have persistent or severe symptoms, you should see your GP in the first instance and they may send you on to an allergy specialist to try and understand what triggers your symptoms. And [the specialist] may also prescribe additional preventative therapy.” It’s caused by an allergic reaction to pollens (especially wind-born pollens from grasses, weeds and trees) as well as moulds, animal fur and house dust. Pollen and other ‘allergens’, irritate the lining of the sensitive nasal passages, inflaming them and causing them to secret fluids. They cause sneezing and a runny or blocked nose. They can also cause other allergic conditions like watery eyes, itchiness and asthma. An allergy is a very specific immune mediated response involving a particular type of immune factor called IgE antibodies. When people become sensitised to an allergen their immune system makes an IgE antibody that can recognise that allergen, priming them to react when they are exposed to that allergen again.
ABC Health News, 23 September 2015 ;http://www.abc.net.au/news/ ;