EEAP 2022: TFA conclusions and uncertainties

“The Montreal Protocol has led to the replacement of ODSs with fluorinated chemicals, some of which can undergo degradation in the atmosphere to give TFA in various yields. TFA is known to have a long environmental lifetime and accumulates in surface and ground waters. At present, there are large uncertainties associated with the concentrations of TFA in various environmental compartments in some regions, as well as the relative proportion of anthropogenic sources related to the Montreal Protocol, compared to the other anthropogenic and natural sources. There is some uncertainty in toxicity values because of the limited number of marine species tested. Current and predicted concentrations (to year 2100) of TFA in the oceans provide a large margin of exposure (thousand-fold) when compared to thresholds of toxicity.”

“Some uncertainties remain in our understanding of the sources, routes of formation, and environmental fate of TFA. Identification and quantification of potential natural sources of TFA are urgently needed. Similarly, better local/regional emission inventories are needed for short-lived precursors of TFA arising from CFC-replacements, as well as characterisation of all other anthropogenic sources of TFA. In addition, reliable estimates of yields of TFA are required for current and new replacement compounds and their partially oxidised degradation intermediates. Finally, there is some uncertainty in toxicity values for TFA because of the limited number of marine species tested.”

About the Environmental Effects Assessment Panel (EEAP)

The UNEP Montreal Protocol Environmental Effects Assessment Panel assesses the various effects of ozone layer depletion. It consists of members who are scientists working in photobiology and photochemistry, mainly in universities and research institutes. The Panel members write the different chapters, sometimes helped by co-authors for special topics. The chapter authors review each other's chapters, and the Panel takes responsibility for the entire assessment. Fifty co-authors are listed for the Environmental Effects Assessment Panel 2022 Quadrennial Assessment Environmental Effects of Stratospheric Ozone Depletion, UV Radiation, and Interactions with Climate Change. Available at Environmental Effects Assessment Panel (EEAP) | Ozone Secretariat (unep.org)