Asthma and pollen
In spring and summer most of us like to spend plenty of time outdoors. However, for many people with asthma, the high pollen levels in the air at those times of the year can bring on asthma symptoms.
What is pollen?
Pollen is the mass of tiny grains produced by a plant for the purpose of fertilisation. Some brightly coloured plants such as wattles have a small amount of relatively heavy, sticky pollen that is spread by birds or insects. Other plants such as weeds, grasses and various trees have smoother, lighter pollen and lots of it. These plants use the wind to spread their pollen, and it is this type of pollen that is a problem for many people with asthma.
How does pollen affect asthma?
Pollen is a common trigger of asthma and produces its effect by means of an allergy. Pollen is thus known as an ‘allergen’, which is an essentially harmless substance that sparks off an abnormal (‘allergic’) reaction in susceptible people. In the case of asthma, the lungs are affected, bringing on the typical asthma symptoms of wheeze, cough, chest tightness and difficulty in breathing.
Your allergy to pollen can mean you may also get the symptoms of hay fever (so-called ‘seasonal allergic rhinitis’) — watery and itchy eyes, sneezing, runny or blocked nose, and itchy ears, mouth and throat — which may also benefit from treatment.
When is pollen a problem?
Pollen causes more of an impact in Australia during summer than at other times of the year. However, in the warm northern regions of Australia, grass pollens can cause problems all year round for people with asthma.
The pollen season occurs when plants and trees have flowers. Some plants will shed large amounts of pollen in the early spring, for example, introduced, European street trees such as the London plane; others will shed throughout spring and summer, for example, grasses such as ryegrass and the weed Paterson’s curse; while others can be a problem for most of the year, for example, she-oaks (native pine trees) and the weed plantain.
Intact pollen grains carried by the wind may irritate your nose and sinuses to cause hay fever symptoms. However, when the air is humid or it rains, the pollen grains absorb moisture from the air and break apart to release tiny starch granules. These particles are allergens and are small enough to be breathed into the small airways of your lungs, and can bring on asthma symptoms. ‘Thunderstorm asthma’ is a term used to describe the rise in the number of people with asthma symptoms around the time of a thunderstorm.
It is also thought that these broken-up pollen grains stick to the exhaust particles from diesel engines, to create particles that are more easily breathed into the lungs.
So high levels of pollen in the air, as occur in the spring and summer, rain, and high levels of exhaust fumes can mean a high-risk day for people who have pollen-induced asthma.
In the warmer months, most television weather forecasts include a pollen count for the day that is based on the average number of pollen grains measured per cubic metre of air. Pollen count may be described as low, medium, high or extreme.
The main culprits in Australia
Most of the plants that cause pollen-induced asthma in Australia are introduced species and include:
- ryegrass — used as a pasture species and in lawns — and other exotic (that is, introduced) grasses that produce a large amount of pollen that can be blown long distances in the wind;
- many exotic trees such as elm, oak, ash and birch; and
- weeds such as Paterson’s curse, plantain and ragweed.
The pollen of some native species, such as native pine trees (she-oaks) and white Cypress pine, can also trigger asthma symptoms.
How to manage the impact of pollen on your asthma
If your asthma seems to be triggered by pollen, you can try the following measures to reduce your pollen exposure; however, research has not yet shown whether this approach effectively controls asthma symptoms.
- Find out which type of pollens can be a problem in your area and aim to avoid them. Many grass pollens contain similar elements, so having a grass-pollen allergy can mean you will have symptoms in response to several different grasses, not just one.
- Check the weather forecast on TV or in the newspaper for the predicted pollen count and plan your day accordingly.
- If possible, try to stay indoors and close the doors and windows on high-pollen, windy days.
- Get to know the times of day that are worse for your asthma during the pollen season. In rural areas, for example, the evening — between 5pm and 6pm — can be the time of day with the greatest amount of pollen in the air. In other areas, the morning may be worse and should be a time when you try to stay indoors.
- Consider having a low-allergen garden incorporating low-allergen plants and shrubs and a lawn or ground cover that needs infrequent or no mowing. Low-allergen plants tend to be those that are pollinated by insects or birds, rather than by wind, and include many native trees and shrubs.
Several strategies that don’t involve avoiding pollen may also be helpful.
- Make sure your asthma is as well controlled as possible by seeing your doctor before the pollen season gets under way. Ask about adjusting your preventive medicine for the likely increased exposure you will have to pollens over the coming months.
- Also ask your doctor about having your pollen allergy confirmed with a skin-prick test or blood tests called RASTs.
- Monitor your peak flow regularly using your peak flow meter, and follow your asthma action plan to adjust your medicine as instructed when your asthma control drops.
- Immunotherapy (repeated injections of very small amounts of pollen allergen over several years to desensitise you) may be a possibility for some people with pollen allergy; ask your doctor.
Last Reviewed: 03 September 2007
