Pollen is a fine powder produced by the male flowers of seed plants when they reproduce (pollination). It travels from one flower to another with birds, insects, and the wind.
Some flowering plants, including wattle trees, produce small amounts of pollen which are spread by birds and insects.
Other plants such as pasture grasses and weeds rely on wind to spread their pollen. These pollens are produced in large amounts and can travel long distances.
Most of the pollens that cause allergies are produced by airborne pollen from northern hemisphere grasses, trees and weeds:
Several types of weeds with highly allergenic pollen have been introduced to Australia and New Zealand, including:
Symptoms are caused by the body's immune system response to inhaled pollen, resulting in chronic inflammation of the eyes and nasal passages. Many people who have these symptoms refer to it as hay fever, but the correct term is allergic rhinitis.
Allergic rhinitis symptoms include:
Allergic rhinitis can increase the risk of people developing sinusitis.
For some people, pollen can directly trigger asthma as well as allergic rhinitis. When pollen granules come into contact with water, starch granules are released that are small enough to be breathed deep into the airways. This causes allergic rhinitis and what is known as thunderstorm asthma in some people.
People who wheeze during spring and/or summer should see their doctor for advice.
In Australia, the amount of pollen particles in the air (also known as pollen count) is lower on the east coast where most winds come from the sea, and where there is protection from westerly winds by the Great Dividing Range. The pollen count is usually higher on the Victorian south coast because most winds are from the north, carrying pollen from the northerly grasslands. In South Australia and Western Australia, the pollen count can vary according to the wind.
Pollination times vary with the plant variety and its location. Trees usually pollinate in late winter and early spring.
Grasses flower next, and the weed 'Plantain' flowers from August through to May.
The main grasses growing in the northern coastal areas are subtropical and mostly flower in January, February, and March. Allergenic grasses in the southern part of Australia are mostly Northern hemisphere grasses, with the main flowering period from October to December.
A history should be taken of the timing of symptoms, identifying plants and trees that grow in the area. It is also helpful to know if symptoms improve when away on holiday.
Once the person’s allergy history has been recorded, skin prick tests using allergens found around their home and work should be done. Blood allergen specific immunoglobulin E (IgE) tests may also be required. Test results should be interpreted by a doctor trained in allergy who will consider the person’s medical history.