[Hugh R]

I know an awful lot about the subject. I'm a Certified Industrial Hygienist (CIH) and that is part of what I do.

Radon you can't feel or get affected by in an acute sense, its causes lung cancer, but is rare. Open the test kit for 24-72 hours and send it in. Available at Walmart, HD, etc.

3M makes dosimeter badges that can test for votatile organic compounds, but older homes likely don't have VOCs which come from plywood, carpet, etc. Also, they only test for what you ask to be tested, typically 2-3 VOCs. If you don't know what to test for, they give you a generic result. Formaldhyde is a good candidate to test for in newer homes.

Older homes have been known to have creosote treated beams, like telephone poles. If so, a little creosote goes a long way towards a smell/odor issue. Basement electric exhaust fans help.

Mold? do you see or smell it? If you see it, or see water intrusion, you don't need a test to confirm it"s presence. You must first fix the water intrusion problem then spray it with a 10:1 water: bleach solution. Bigger water intrusions may require removal of drywall or lathe and plaster. The U.S. EPA has a lot of info on line on this subject. Air sampling for mold is $ and mostly unnecessary unless you see/smell mold.

Tell me why you think you might have indoor air contaminants?