This is a very small sample of odor sources.

Hidden mold inside a toilet tank.

Sewer gasses leaking indoors through soil pipe.

Volatile organic chemical fumes from unsealed paint cans.

Mold and bacteria growing underneath a refrigerator.

Combustible gas and emissions leaking from a water heater.

Dog urine concealed underneath carpet.

Cat urine inside of carpet.

Unencapsulated sub-flooring.

Man-made chemical deodorizers.

Chemicals used in personal care products.