Ozone and TFA Impacts in North America from Degradation of 2,3,3,3-Tetrafluoropropene (HFO-1234yf), A Potential Greenhouse Gas Replacement

• Published in: Environmental science & technology Vol. 44; no. 1; pp. 343 - 348
• Main Authors: Luecken, Deborah J, Waterland, Robert L, Papasavva, Stella, Taddonio, Kristen N, Hutzell, William T, Rugh, John P, Andersen, Stephen O
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.01.2010
• Subjects: Air Pollutants - chemistry; Applied sciences; Aquatic life; Biodegradation; Emissions; Environmental impact; Environmental Modeling; Exact sciences and technology; Fluorocarbons - chemistry; Gases - chemistry; Greenhouse Effect; Greenhouse gases; Models, Theoretical; North America; Outdoor air quality; Ozone; Ozone - chemistry; Pollution; Rain; Simulation; Trifluoroacetic Acid - chemistry; North America; America; United States > US; USA; Air conditioning; Current source; Atmospheric fallout; Pollutant behavior; Regional scope; Troposphere; Ozone; Air quality; Wet deposition; Pollutant emission; Modeling; Dry deposition; Persistence; Transport process; Lifetime; Three dimensional model; Rain; Efficiency; Greenhouse gas; Air pollution; Anthropogenic factor
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es902481f

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 80× lower than the lowest level considered safe for the most sensitive aquatic organisms.