title: Ozone and TFA impacts in North America from degradation of 2,3,3,3-Tetrafluoropropene (HFO-1234yf), a potential greenhouse gas replacement.
abstract: We use a regional-scale, three-dimensional atmospheric model to evaluate U.S. air quality effects that would result from replacing HFC-134a in automobile air conditioners in the U.S. with HFO-1234yf. Although HFO-1234yf produces tropospheric ozone, the incremental amount is small, averaging less than 0.01% of total ozone formed during the simulation. We show that this production of ozone could be compensated for by a modest improvement in air conditioner efficiency. Atmospheric decomposition of HFO-1234yf produces trifluoroacetic acid (TFA), which is subject to wet and dry deposition. Deposition and concentrations of TFA are spatially variable due to HFO-1234yf's short atmospheric lifetime, with more localized peaks and less global transport when compared to HFC-134a. Over the 2.5 month simulation, deposition of TFA in the continental U.S. from mobile air conditioners averages 0.24 kg km(-2), substantially higher than previous estimates from all sources of current hydrofluorocarbons. Automobile air conditioning HFO-1234yf emissions are predicted to produce concentrations of TFA in Eastern U.S. rainfall at least double the values currently observed from all sources, natural and man-made. Our model predicts peak concentrations in rainfall of 1264 ng L(-1), a level that is 80x lower than the lowest level considered safe for the most sensitive aquatic organisms.
authors.affiliation: US Environmental Protection Agency, Research Triangle Park, North Carolina 27709, USA. luecken.deborah@epa.gov
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: Luecken
authors.forename: Robert
authors.initials: R
authors.lastname: L Waterland
authors.forename: Stella
authors.initials: S
authors.lastname: Papasavva
authors.forename: Kristen N
authors.initials: KN
authors.lastname: Taddonio
authors.forename: William T
authors.initials: WT
authors.lastname: Hutzell
authors.forename: John P
authors.initials: JP
authors.lastname: Rugh
authors.forename: Stephen O
authors.initials: SO
authors.lastname: Andersen
mesh_terms: D000393:Air Pollutants / Q000737:chemistry*; D005466:Fluorocarbons / Q000737:chemistry*; D005740:Gases / Q000737:chemistry*; D017752:Greenhouse Effect; D008962:Models, Theoretical; D009656:North America; D010126:Ozone / Q000737:chemistry*; D014269:Trifluoroacetic Acid / Q000737:chemistry*; D006845:Hydrocarbons, Fluorinated
chemical_list: D000393:Air Pollutants; D005466:Fluorocarbons; D005740:Gases; D010126:Ozone; D014269:Trifluoroacetic Acid; C528198:2,3,3,3-tetrafluoropropene; D006845:Hydrocarbons, Fluorinated