Indoor air contains an abundance of chemicals harmful to humans. Although many of these chemicals are released into the environment in minute amounts, when hundreds of chemicals mix, they can form a ``pea soup concoction that can create a variety of health problems, including respiratory disorders such as asthma,'' says Bill Wolverton, author of ``How to Grow Fresh Air.''

Here are just a few chemicals and the problems they can cause.

-- Acetone: This is found in nail polish remover and various solvents. It is very drying to the skin.

-- Ammonia: Found in many cleaning solutions, it can create a toxic gas if mixed with bleach. It is also very irritating to the lungs.

-- Benzene: Suspected of causing leukemia in children, this is found in paint, varnish, gas and just about any chemical that has an odor.

-- Formaldehyde: This is an especially dangerous chemical that is found in many synthetic products, such as particle-board furniture, paint and carpeting.

It is a strong irritant and is believed to cause a condition known as multiple chemical hypersensitivity in some individuals, which leads to asthma and multiple allergies.

-- Trichloroethylene: Found in a wide variety of synthetic products, such as solvents, varnish and glue, it is a known carcinogen that can cause cirrhosis of the liver.