Air freshener

Air fresheners are consumer products used in homes or commercial products used in restrooms that typically emit fragrance. There are two broad air freshener categories: continuous action and instant action. Continuous action products include: scented candlesand devices which use a candle flame or some other heat source to heat and vaporize a fragrance formulation; Incense burners; wall plug-ins which either use piezoelectric technology to aerosolize fragrance or heat to vaporize it; fragrance impregnated gels which release fragrance as the gel evaporates sometimes with the help of an electric fan; wick and reed diffusers which release fragrance by evaporation from fragrance-soaked wicks or wooden reeds; and fragrance impregnated materials like floor wax, paper, plastics, wood which release fragrance by off gassing; and lastly nebulization systems which convert liquid fragrances into a vapor in a cold process without the use of heat.

Instant action systems are mainly aerosol sprays, or atomizers. The aerosol spray uses a propellant and fragrance packaged under pressure in a sealed metal or glass container with a valve which is opened by pressing down a button which contains a spray nozzle – the actuator. When the container's valve is opened by pressing the actuator, fragrance is forced through the spray nozzle located inside the actuator to create a mist of droplets containing fragrance. These droplets are 30 to 50 micrometres in diameter. Theatomizer is a glass, metal or plastic container of fragrance which operates in a similar fashion except that the actuator is a pump which when pressed a few times creates the pressure to aspirate the fragrance from the container through a tube into the actuator and spray nozzle. The mist created contains droplets 50 to 150 micrometres in diameter. A recently developed type of aerosol packages a plastic bag of fragrance into a can. The bag is attached to the valve/actuator/spray nozzle and sealed in the can surrounded by air under pressure. When the actuator is pressed, the valve opens and the liquid forced through the nozzle by the pressure around the bag. This is called "bag-on-valve" technology.

Global retail sales of air care products were valued at more than $6 billion in 2006 and are forecast to reach $7.3 billion by 2010.^[1]

Air fresheners introduce fragrance into the air of interior spaces either as droplets which transition to vapor or as the molecules of fragrance ingredients evaporating from a source. Fragrance diffuses into the air to mask other odors or to introduce a specific odor.

The control of odors is addressed by various methods;

1. Adsorption: Adsorbents like zeolite, activated charcoal or silica gel may be used to remove odors.
2. Receptor Blockers: These are specially formulated compounds, usually delivered in cleaning products and waxes, which block the human scent receptors from detecting certain odors.
3. Oxidation: ozone, hydrogen peroxide, peroxide; chlorine, chlorate other oxidizing agent can be used to oxidize and remove organic sources of odors from surfaces and, in the case of ozone, from the air as well.
4. Air sanitizer: Odors caused by airborne bacterial activity can be removed by air sanitizer that inactivate bacteria.
5. Masking: Overwhelming an odor with another odor by any of the means described above.