There is no one test that can comprehensively determine indoor air quality. If you suspect a problem with indoor air quality, begin by discussing the problem with others in the building in order to investigate the possible sources of indoor air contaminants.
Indoor air contaminants can come from many sources, and sometimes a comprehensive building inspection is required to determine the nature of a problem. Indoor air contaminants can be chemical or biological materials. Contaminants may come from materials inside the building or may infiltrate from outdoors through ventilation systems. After you have determined possible sources of the problem, test for the suspected contaminants.
Some common indoor air contaminants are radon, carbon monoxide, mold and allergens. Many inexpensive kits meeting EPA requirements for testing radon are available in hardware stores. Homeowners can monitor carbon monoxide levels with a device similar to a smoke detector installed in the home. It is also possible to test mold and allergens using home kits, but homeowners should hire a reputable contractor for more reliable results.
It is often difficult to test for other contaminants, such as formaldehyde, benzene or pesticides. It may be possible to alleviate problems with these contaminants without the need for extensive testing simply by increasing ventilation in the building. It is often possible to eliminate contaminants that are present in large amounts for short times, or that build up slowly over long periods, by opening a window or turning on an exhaust fan.