Spores of molds and pollens of plants are the most common airborne allergens that can cause hay fever, asthma, and other allergic reactions. Depending on where you live and the time of the year and the weather conditions, the type and number of pollens and molds in the air we breathe vary. There is where pollen and mold counts come in handy.
Only certified agencies can count pollen and mold levels in the air. The American Academy of Allergy, Asthma and Immunology (AAAAI), in cooperation with the National Allergy Board (NAB) provides official figures on pollen and mold counts. Their data is based on data collected by more than 85 counting stations all over the US.
How does pollen and mold counting work?
The Saint Louis County Health Services tells us the following:
Counters use air sampling equipment to capture airborne pollen and mold. Recently, the Environmental Health Laboratories switched from using a rotorod impaction device to using a Burkard slit-type volumetric spore trap. The rotorod sampled only at specific time intervals while the Burkard is able to continuously sample over a 24 hour period. The device is mounted on the roof of a centrally located County building away from any obstructions. It uses suction to pull air through a slit-type opening. Inside the slit is a greased, flat surface (a collection tape) that advances in increments over time. This greased surface collects any particles that are sucked in with the air. How are pollen and mold counted? The collection tape is removed from the sampling device and brought to the laboratory. Here it is stained and prepared for analysis. The sample can then be magnified 400 times to count the pollen grains. For some mold spores, the sample must be magnified 1000 times to be seen and counted. Using the exposure time, the volume of air sampled, and the number of pollen grains or mold spores counted, calculations can be made to determine the number of particles per cubic meter of air sampled. This is the number reported by the laboratory.
How can you use these counts in managing your allergies?
The AAAI has come up with recommended definitions of low, moderate, high and very high concentration levels of molds and pollens. These levels represent outdoor exposures only. Based on these levels, comparison between different areas and regions can be done. These counts are also useful in the management and treatment of allergies due to airborne allergens.
Other resources on airborne allergens: