Worldwide, people have been searching for ways to hide unwanted odours and “freshen” the air around them for ages. This is why air fresheners were invented.
The first modern air freshener was introduced in 1948. Its function was based on a military technology for dispensing insecticides and adapted into a pressurised spray using a chlorofluorocarbon (CFC) propellant. The product delivered a fine mist of aroma compounds that would remain suspended in the air for an extended period of time. This type of product became the industry standard, and air freshener sales experienced tremendous growth. In the 1950s, many companies began to add chemicals that counteract odours to their fragrance formulas. This is according to Wikipedia, an encyclopaedia.
According to Fresh Products, an odour control manufacturing company, by the 1950s, the aerosol air fresheners continued to be the standard method for releasing a burst of fresh air into a room, so companies began adding ester, pre-polymers, and long-chain aldehydes to help neutralize odours. As testing of the aerosol sprays became more rigorous, concerns were raised over the negative effects of the CFCs.
By 1970 companies were constantly coming up with new and more effective ways to neutralise odours for longer periods of time while reducing costs. At this point you could find a variety of different air fresheners in a magnitude of scents all claiming to eliminate the odours from cigarette smoke to annoying pet scents.
In the 1980s, the Natural Resource Defense Council found that 12 common air fresheners were causing negative side effects in people with asthma and stunted reproductive development. Since then, a slew of air freshening diffusers have been released as alternatives to aerosol sprays that claim a low amount of carcinogenic material.
By the 1990s the public was becoming somewhat bored of the average aerosol that could contain the scents of the forest, so new and old innovative ways were enlisted to continue the hype around air fresheners. This is according to Weebly, a web hosting service.
Things like potpourri, made up of dry spices and herbs, battery powered fans that circulated scents around a room, modified candles, and most popular of all, plug-ins, were beginning to hit the market. Plug-ins offered a new way to retain pleasant aromas in a room without the hassle of having to whip out an aerosol can and spray the room, which sometimes left things sticky and wet when sprayed on upholstery.
Instead plug-ins allowed homeowners to retain scent for over a month by simply installing a small device into an electrical socket, the device consisted of a plastic tray filled with a fragrant gel, as the device heats up (thanks to electricity) the fragrance is slowly diffused into the air over a period of time.
Now, you can get air fresheners in candles, plastics, potpourri, and even the traditional oil diffusers.