Health

Mold is common where water tends to collect, such as shower curtains, window moldings and damp basements. It can also be found on rotting logs, hay, mulches, commercial peat moss, compost piles and leaf litter. This allergy is usually worse during humid and rainy weather.
Animal dander is made up of bits of skin and hair from pets. Both are allergens. You can be exposed to dander when handling an animal or from house dust that contains dander.

Dust contains allergens, including dust mites. Dust mites are tiny living creatures found in bedding, mattresses, carpets and furniture. They like places where it's warm and humid. They live on dead skin cells and other things found in house dust.

Common allergens in the air are pollen, mold, animal dander and dust. Many other things, such as those listed in the box above, can make your allergy symptoms worse.

Pollen comes from trees, grass and weeds. Allergies that occur in the spring (late April and May) are often due to tree pollen. Allergies that occur in the summer (late May to mid-July) are often due to grass and weed pollen. Allergies that occur in the fall (late August to the first frost) are often due to weed pollen.

Pollen from flowers usually doesn't cause problems in people with allergies because the pollen is too heavy to float in the air. These plants rely on insects to carry their pollen.