1,1-Difluoroethane (HFC-152a)

1,1-Difluoroethane (HFC-152a) is a hydrofluorocarbon used as an aerosol propellant. It has only two carbons and two fluorines on the same carbon — it is **not** a per- or polyfluoroalkyl substance (PFAS) under the OECD definition. The PFAS test requires at least one fully fluorinated methyl or methylene group; HFC-152a has only a CH₃-CHF₂ structure and is excluded. GHS classification at typical use is H220 (extremely flammable gas) and H280 (gas under pressure). It is not classified as an asthmagen, sensitizer, or carcinogen. The compound has limited atmospheric persistence (~1.4 year lifetime) and a Global Warming Potential of ~138 (vs CO₂ = 1) — significant in industrial-scale release but trivial at consumer-can quantities. Not aquatic-toxic; rapidly disperses as a gas on release. VOC-exempt under EPA and CARB regulations as a fluorinated propellant. Used in Ozium glycol-aerosol products as a partial replacement for hydrocarbon propellant to manage flammability at the can level.