What Are the Worst Airborne Allergens?

Seasonal allergies are a constant source of struggle for people who live with them. According to the National Institutes of Health, 17.9 million Americans in the last 12 months have been diagnosed with hay fever. Allergies can be as unpredictable as the weather, and with the warm period of the seasons becoming longer due to global warming, allergies that would only stick around for the summer months might still be around into October and November. People can also develop allergic responses to indoor allergens as well, and staying cooped up indoors may not be the best solution for everyone, especially since outdoor allergens can accumulate indoors as well. Knowing the worst allergens can be a step toward getting the best treatment for airborne allergies.


The allergic response is familiar to anyone who has had a springtime runny nose. The body essentially raises a false alarm to the presence of foreign particles that enter the body from the outside. Instead of harmlessly allowing the particles to pass through the system, the body produces antibodies to fight off the foreign particles in a process that eventually releases histamines. Histamines are responsible for all of the telltale signs of an airborne allergen reaction: sneezing, post nasal drip, conjunctivitis, and watery eyes. Generally, as long as the airborne allergen is present, the body in those with allergic reactions will continue to fight it.

By far, the worst airborne allergens for most people come from plants. Hay fever, as it is commonly known, refers to the onset of allergies that typically came during the "haying" season. Plants produce pollens that create these allergies with trees, grasses, and weeds all producing copious amounts of pollen during their growing season. Ragweed plants individually, for instance, will produce nearly a billion pollen grains in one growing season, and it is one of many plants that have responded well to the longer growing seasons we have been experiencing. Some trees like cedar do not produce their pollen grains in the summer and spring months when people expect allergies to occur. These plants produce their pollens in the winter months; thus, these kinds of allergies can strike at any time of the year.

Dust and dust mites produce similar problems for people with allergies to them. Although dust is easily controlled inside the home, dust mites pose another problem altogether. These small organisms feed on the organic detritus in the environment, such as human skin. It is an enzyme in their feces that produces an allergic reaction and is responsible for asthma and upper respiratory problems in a host of people. This organism survives everywhere and is well suited to live in bedding and pillow cases and sheets.

Molds and animal dander pose similar problems for people, although mold is sometimes a more challenging issue to control depending on the climate that one lives. More humid climates will produce more mold spores from decaying matter. Allergies from animal dander are caused by the flakes of skin entering the respiratory system and creating numerous allergic responses.

One of the best ways to control airborne allergens indoors is through a HEPA filter for the heating and air-conditioning system, or even better, a standalone air purifier unit in the absence of central heating and air. Unfortunately, doctors have not invented a magic allergy cure. However, it is understood that genetics play a central role in allergies, and there may yet come a time when airborne allergens do not pose such a problem for people.

Trisha Tate writes for several air quality sites and recommends the IQAir air purifiers or the IQAir Healthpro Plus for clean air in your home.