Acetone

Acetone (propan-2-one) is the simplest ketone solvent — familiar as nail polish remover. In aerosol air fresheners, it serves as the liquid carrier that the fragrance dissolves into; the aerosol propellant (propane/butane) vaporizes the acetone-fragrance mixture and delivers it as fine droplets. Acetone is notably VOC-exempt in US regulations (both EPA and California ARB), which is why it can be present at 60–80% by weight without triggering aerosol VOC compliance failures. Despite that regulatory status, it is a real inhalation hazard at high concentrations — OSHA PEL is 1,000 ppm TWA, and the STOT SE 3 (H336, narcotic effects) classification reflects genuine risk from sustained exposure. Brief bursts in a car interior disperse quickly, keeping actual doses well below occupational limits. Not listed on Prop 65. Readily biodegradable in both aerobic and anaerobic conditions.