EPA has posted warnings on their website about TANKS 4.09d and has cautioned that AP-42 should be used to estimate storage tank emissions rather than relying on TANKS 4.09d. However, EPA is also considering revisions to AP-42 chapter 7.1 that will result in changes to estimated emissions for storage tanks. This webinar will review the problems with TANKS 4.09d as well as preview changes to AP-42 that are currently under consideration.