No, but it’s common that they do. Gravity furnaces weren’t terribly efficient so wrapping either the ductwork in asbestos, the furnace itself, or both, was something done regularly. This allowed the system to retain more heat. At the time, this greatly enhanced the efficiency of the furnaces but it wasn’t until later that we became aware of just how carcinogenic and dangerous asbestos could be.

Although the use of asbestos has declined since the 1980s, it remains in several different types of building construction materials for insulation and as a fire retardant. Typically, asbestos can be found in materials such as ceiling and floor tiles, heat-resistant fabrics and coatings, and roof shingles. You may also find asbestos in textured paint and patching compounds.

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.

DIY kits are available, but professional testing ensures accurate results and compliance with regulations.