Melbourne Pollen Count - Frequently Asked Questions

What is pollen?
Pollen contains the plant's male gametes.  The closest analogous cell type in a human is male sperm.

Why is there pollen in Melbourne's air?
Plants are immobile and so cannot go searching for suitable mates the way animals do. To ensure their gametes reach receptive females, plants have developed many ways of distributing their pollen.  Some species use the wind to carry pollen between plants. These plants have very simple, dry flowers that do not secrete the nectar that attracts birds and insects.  Wind-borne pollen can drift considerable distances.  Pine pollen, for instance, can be carried hundreds of kilometres. But, then pine pollen has wings that serve as floats! Pollen of wind-dispersed species such as rye grass, the major source of pollen in Melbourne's air in the late spring and early summer, is relatively small in size, (usually <30 micrometers), has smooth outer surface, and is relatively dry and powdery. A number of factors, such as wind speed, humidity, down gradient, etc., determine how far such pollen will travel.  Other plant species use insects and birds to carry their pollen between plants.  These plants produce pollen that is larger in size (>30 micrometers), has extensive surface ornamentation, contains high levels of water, and also has a sticky surface. These pollen are also heavier and sometimes occur in clumps. They have less chance of drifting any distance on the wind.

Can you recommend any medication for my allergies?
The Melbourne Pollen Count does not offer medical advice.  Please consult your doctor to discuss proper treatment of your allergy symptoms.

How are pollen counts done?
We use an air-sampling device called a Burkard spore trap to capture airborne pollen on a glass slide, where it can be stained with a dye and counted using a microscope.  During the season, a slide is removed from the trap at the same time each day and counted twice.  The first counts all types of pollen and the second just the grass pollen (which has a distinctive shape).  Our daily pollen count is a report of grass/all kinds of pollen (as grains per cubic metre of air) caught in the trap in the previous 24 hours.  Our pollen forecast is based on this count and on the weather forecast for the next 24-hr period.

Why is pollen counting only done over spring and summer?
We usually begin reporting in October, when grasses start flowering and there are measurable amounts of grass pollen in the air.  By the middle of summer when the grass has died off, there are again minimal amounts of amount of grass pollen in the air.  During the grass pollen season the count is done daily and the information distributed through various media outlets.

How many pollen-counting stations are there in Victoria?
The only station currently operating in Victoria is at the University of Melbourne.  Other capital cities have their own pollen count stations.

What factors affect the daily pollen count?
A number of factors affect the count, including daily fluctuations in temperature, wind conditions, humidity and precipitation, and of course the biology of the plants themselves.  Many plants flower in the morning so concentrations of airborne pollen are usually highest between 5 a.m. and 10 a.m.

Weather conditions also affect pollen levels. The biggest factors affecting pollen counts are wind, and humidity.  Melbourne's worst pollen days are characterised by hot northerly winds that bring pollen in to the city from pastures in the surrounding countryside.  When the air is humid, such as during or after it rains, pollen that is small, light and dry and easily spread by wind, becomes heavy with moisture and can't travel as far.

Is the pollen season the same from year to year?
Not exactly.  The beginning and end of the grass pollen season depends on the previous year's weather (how much grass is growing) and current weather (how much grass is flowering).

Where can I find the daily pollen count and why don't you put it on this site?
The daily count and forecast are not available on our webpage because very few people even know this site exists. The pollen count does however get posted on the Asthma Victoria website (http://www.asthma.org.au/). We also supply it each day of the pollen season to key media outlets in Melbourne. You can find the daily count and forecast by watching the Channel 9 evening news, reading the Herald Sun and Age, or by tuning in to radio station 3AW."

Where can I get historical data (past pollen counts, etc.)?

Files of pollen counts for the past several seasons can be downloaded from the count data page.