The toxic effects of air fresheners differ depending on the formulation. Small amounts of most air fresheners are usually not dangerous. Swallowing the gel-type evaporative beads or reed diffuser solutions can cause serious effects in children.

Air fresheners have been used to mask unpleasant odors for decades. The first type developed for home use were aerosols. These products are sprayed into the air and create a fine mist of fragrance that lingers. When the use of aerosols became unpopular due to health and environmental concerns, manufacturers responded by reformulating air fresheners as scented oils, reed diffusers, solids, and gels.

High-tech versions are heat activated or can automatically spray into the air throughout the day. Even the names of the fragrances have been revamped. Traditional scents such as “rose” or “lemon” have been replaced with more exotic sounding names such as “Tahitian spring mist” or “dewy citrus orchard.”

Most air fresheners contain a variety of fragrances and essential oils. Fragrances are chemical compounds that have pleasant odors. Essential oils are naturally occurring oils typically obtained from plants. The oil contains the essence of the plant’s fragrance, hence the term “essential”. Examples of essential oils include cinnamon oil, pine oil, and lavender oil.

Liquid air fresheners, such as plug-in refill bottles and reed diffusers, typically contain fragrances and essential oils dissolved in a solvent like isopropyl alcohol, which is also found in rubbing alcohol. The evaporation of the solvent helps carry the fragrance into the air.

Solid air fresheners, such as the cone-type products, typically contain the fragrance embedded in wax. Gel products, such as the evaporating beads, allow slow evaporation that prolongs the presence of the fragrance. Aerosols sprays use compressed gas propellants like butane or propane. While many of the spray products are designed to just add fragrance to the air, others help remove odors by using disinfectants, which are chemicals intended to kill bacteria or mold. An example of one of these disinfectants is ethanol, which is also found in alcoholic beverages.

Despite their popularity, there are concerns that these products increase indoor air pollution and pose a health risk, especially with long-term exposure. Air fresheners release volatile organic compounds (VOCs) into the air. A VOC is a type of chemical that turns into a vapor or gas easily at room temperature.

Health problems are thought to occur from the chemicals in the air fresheners and from their secondary pollutants. Secondary pollutants are formed when a product’s chemicals combine with the ozone already in the air. Even when these products are used as directed, there are concerns about health problems with repeated exposure. Unintentional injuries have been reported with these products, including burns when flammable air fresheners have been ignited by a nearly flame.