For some reasons, every area in close proximity to airports with moderate to high piston engine aircraft traffic have exceptional high local exposure (according

For some reasons, every area in close proximity to airports with moderate to high piston engine aircraft traffic have exceptional high local exposure (according to EPA). There could be a correlation or even a causation link. EPA at least think so, which is why they changed the rules in 2008 by issuing a new minimum standard. The new replacement fuels are good, but they have one general large drawback. They require a recertification of the engine/frame of the plane. According to the lobby group AOPA, it will cost the industry in excess of $150 billion annually in the US alone. In response, EPA issued an statement that there will be no phase-out date for planes to meet the new minimum standard, saying that it is the FAA responsibility to issue a process so that airplanes fulfills the new minimum standard. The FAA in turn said that regulating lead in avgas is an EPA responsibility, and they will not issue a phase-out date for planes to meet the new minimum standard. That has been the last word from both agencies since 2010.