"Is there some way to test air quality in an environment? Some kind of DIY test or tool that can be used? Or, do you have to call in some kind of professional?"
Add your two cents here.
Get a canary, if you wake up one morning and he's laying on the bottom of the cage get the hell out of the house.
To assess general air quality in a home, you could try a photoionization detector (PID, which is used to screen ambient air for volatile or semivolatile organics. Again, this is not a method to identify specific air constituents, but can help the user to identify specific areas, items, etc. in a home that may be contributing to air quality issues in the home. You can rent a PID for $40 to $0 a day.
Install a carbon monoxide detector. If they detect a change in the levels of carbon monoxide in your home, an alarm will sound. Use a radon detection kit.These kits must be left open and undisturbed for three days. Use a test for dust mites, molds, and mildew test kit. After then, ship it to a lab to get your results.
Sometimes you might just want to test for a certain allergen or chemical, like Radon. If you're doing a more specified test, then the cost to test indoor air quality might be cheaper since it will be more focused. Pros who specialize in this kind of testing will take a sample and will be able to diagnose the problem pretty quickly if there's only one result.
If you've decided to check for anything and everything, then the cost to test indoor air quality will increase. This requires taking more samples and running more tests. This will also increase the consultation time when the results come back to decide how to fix whatever issues may have come up. However, this is a good way to check a lot of potential problems off the list or to take care of anything that might be in your air.