Pollen ultimately comes from trees, grass and weeds. Allergies that occur in  the spring (April into May) are usually due to tree pollen. Allergies that occur  in the summer (May to late July) are often caused by grass and weed pollen.  Allergies that occur in the fall (August into November) are usually caused by  ragweed.

Mold is very common where water collects, such as shower curtains, window  moldings and damp basements. It's usually found in rotting logs, hay, peat moss,  compost piles and leaf litter. This type of allergy is often worse when the  weather is humid and rainy.

Animal dander is another allergen that affects millions of people. Proteins  that are found in the skin, saliva, and urine of pets such as dog and cats are  considered allergens. People are exposed to dander when handling an animal or  from common house dust.

Dust is another prominent allergen that's extremely hard to avoid. Most  allergens, including dust mites, are actually in dust. Dust mites are  microscopic creatures that are found in mattresses, bedding, carpeting and even  upholstered furniture. They can live on dead skin cells and other common items  that are found around the house.

How to Avoid and Prevent Allergens:

Pollens - Shower before bedtime to wash off pollen and other  allergens on your skin and in your hair. Try to avoid going outside, especially  when it's dry and windy. Keep your windows and doors closed and always use an  air conditioner at home and in your car.

Mold - You can cut back the amount of mold in your home by  getting rid of houseplants and by regularly cleaning shower curtains, bathroom  windows, damp walls and indoor trash cans. Use a mixture of bleach and water to  kill any mold. Turn on your fans to help increase air circulation and to help  prevent any mold. Do not put carpet in bathrooms or any rooms that are damp and  always use paint that's mold resistant instead of wallpaper. Lowering the  humidity in your home to 50% or less can also help reduce mold. Home air quality  can be helped by using a dehumidifier, keeping the temperature set around 70  degrees and cleaning or replacing air filters inside your house.

Pet Dander - If your allergies are really bad, you might  want to give away your pets or at least keep them outside. Dog or cat dander  usually collects in dust within the house and can take over four weeks to  completely go away.

Fortunately, there are several ways to help reduce the amount of pet dander  inside your home. Allergen-resistant bedding, air filters and well-groomed pets  can drastically reduce pet dander inside your house.

Dust and Dust Mites - In order to get rid of dust mites, you  should remove any drapes, feather pillows, upholstered furniture or non-washable  comforters, as they can be excellent places for dust mites to live. Always  replace your carpets with linoleum or wood flooring. Floors should be mopped  regularly with a damp mop and always wipe any smooth surfaces with a damp cloth.  Always vacuum plush furniture and curtains, as well as the floors. Wash all  bedding in hot water (hotter than 135°F) every single week and do not use  mattress pads. Make sure you cover your mattress and pillows with allergy-proof  plastic covers and try to keep the humidity low in your house.