Aerosol fresheners generally contain hydrocarbons as propellants and solvents. A synthetic fragrance is added to mask any other odours.

Health effects
The fragrances in air fresheners may also inhibit the ability to smell. There have been reports of emotional side effects after prolonged use of air fresheners. Block-type fresheners, often used in toilet bowls, usually contain paradichlorobenzene (PDB), an organochlorine. PDB has a strong odour masking other smells but has been associated with liver and nerve damage.

Environmental effects
Air fresheners add to the chemical load on the environment.

Alternatives
Clean thoroughly and regularly those areas in the house where unpleasant odours are likely to occur. Where possible, allow fresh air to circulate through the rooms. Lighting a match then blowing it out can disperse unpleasant odours.