There is no way to completely avoid wind-borne pollen, even if you seal yourself indoors. Find out when it's pollen season and check your local pollen count to gauge the possible severity of your pollen allergies on a given day. Although there are thousands of molds and yeast types, only a few are considered nasal allergy triggers. Molds grow in soil, compost piles, rotting logs, and fallen leaves. Some even attach to grains such as wheat, oats, and barley.
Molds can easily grow indoors as well.
They flourish in damp basements, closets, bathrooms, fresh food storage areas, refrigerators, houseplants, air conditioners, humidifiers, garbage pails, mattresses, and upholstered furniture. Like pollen, there must be a large amount of mold spores to spark nasal allergy symptoms. Since mold spores are found almost everywhere, they sometimes outnumber pollen spores in the air. Fortunately, there are only a few dozen types that pose a threat to people with nasal allergies. But if your nasal allergies persist through the winter months, you may be allergic to dust mites.