Potential impacts of CF3I on ozone

Iodotrifluoromethane (CF 3 I) has been considered to be a candidate replacement for bromotrifluoromethane (CF 3 Br), which is used in aircraft for fuel inerting and for fire fighting. In this study, the chemical effects of aircraft-released CF 3 I on atmospheric ozone were examined with the University of Illinois at Urbana-Champaign 5 two-dimensional chemical-radiative-transport (UIUC 2-D CRT) model. Using an earlier estimate of the aircraft emission profile for tank inerting in military aircraft, the resulting equivalent Ozone Depletion Potentials (ODPs) for CF 3 I were in the range of 0.07 to 0.25. As a sensitivity study, we also analyzed CF 3 I emissions associated with fuel inerting if it were to occur at lower altitudes using an alternative estimate. 10 The model calculations of resulting effects on ozone for this case gave ODPs≤0.05. Furthermore, through interactions with the National Institute of Standards and Technology (NIST), we analyzed the potential effects on ozone resulting from using CF 3 I in fire fighting connected with engine nacelle and auxiliary power unit applications. The scenarios evaluated using the NIST estimate suggested that the ODPs obtained by 15 assuming aircraft flights occurring in several different latitude regions of the Northern Hemisphere are extremely low. According to the model calculation, the altitude where CF 3 I is released from aircraft is a dominant factor in its ozone depletion effects. On the assumption that the CF 3 I emission profile is representative of actual release characteristics , aircraft-released CF 3 I has much lower impacts on the ozone layer and can be a 20 qualified substitute of CF 3 Br in engine nacelles.