Outdoor Allergen Exposure

Outdoor allergen exposure, particularly pollen, and to a lesser extent fungal spores, cause seasonal allergies to many individuals worldwide. While it is not possible to totally avoid exposure to those allergens, it is feasible to minimize it. For this purpose, it is important to be aware of the types and levels of airborne pollen and fungal spores present outdoors day-to-day during various seasons of the year in different geographical locations.

The National Allergy Bureau (NAB), founded in the early 1960s, is a section American Academy of Allergy Asthma and Immunology dedicated to distribute pollen and spore counts nation wide. For this purpose, a number of certified stations collect outdoor air samples and provide pollen and spore count data to the community. Those data are included in the NAB web site and distributed to the public.

Other organizations in the world, for example, the British Aerobiology Federation in the United Kingdom, are analogous in scope to the NAB. Those organizations also report regular pollen and spore counts to the public. In addition, they promote the science of aerobiology at different levels.

Pollen and spore counting and identification are a time-consuming task to perform that requires a high level of expertise. The fast pace that modern society operates, together with the perception that the technology currently used to perform the counts and identification has not changed in many years, has contributed to a decline in the interest of young individuals to learn about the complex area of aerobiology.

To partially overcome the caveat mentioned above, various companies are developing systems and equipment to automate particle counting and identification to the best possible extent. Current efforts in that regard indicate that while automatic particle counting is feasible, proper identification of the particles is very challenging to perform using automatic approximations. Side-by-side comparisons of the pollen/spore counts and identification determined using automatic systems and by optical microscopy should be performed to validate and optimize technology.

Another benefit of the data derived from the completion of aerobiological surveys is to assist pharmaceutical companies conducting clinical trials that involve subjects with seasonal allergies. The purpose of these trials is to ascertain the safety, efficacy, and doses of particular medications or immunotherapy formulations before they can be marketed.

To conduct those clinical trials, individuals sensitized to particular outdoor allergens are selected and allocated into various groups, receiving either an active treatment or a placebo before or during particular pollination seasons. However, due to the limitations associated with natural exposure to outdoor allergens, environmental chambers are being developed and validated to perform exposure challenges under controlled conditions. While this approximation is optimal for the purpose of licensing and marketing particular products, it does not reflect the types and levels of exposure to outdoor allergens that individuals experience under natural conditions, which is ultimately responsible for sensitization and allergy symptoms.

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