Asbestos-containing materials are not easily affected by water and do not disintegrate or dissolve when exposed to it. However, porous materials can deteriorate due to water exposure, leading to the release of asbestos fibers into the air. The settling of asbestos fibers can also occur as water makes them heavy, which reduces the risk of airborne exposure, though future disturbance of the materials could cause risk. Wetting asbestos-containing materials does not constitute safe removal, and the proper handling and disposal of asbestos materials should be left to professionals.

Mold, VOCs, radon, carbon monoxide, and particulate matter are typically measured.

Knob and tube wiring is an older type of electrical wiring that's no longer used and generally not considered safe. However, some homes still have it, or may have a knob and tube wiring system that was incorrectly modified or rigged to work with a modern electrical system. Knob and tube wiring may contain asbestos insulation, but the only way to know is to have the material professionally tested.

While a professional can always help, there are some common plumbing culprits you can check yourself to see if you can find the sewer gas smell. For example, you should check your water traps, sometimes called P-traps and S-traps, which are located under sink, shower, and laundry drains. The wax ring beneath the base of your toilet, which creates a watertight seal with the plumbing, could also have gone bad.