A hidden source of ozone-damaging chemicals—leaks from industrial feedstocks—may be slowing the ozone layer’s recovery. Fixing this issue could shave years off the timeline and reduce future health risks. Credit: Shutterstock The 1987 Montreal Protocol is often described as the most successful environmental treaty ever created. It has led to a steady global phaseout of chemicals that once damaged the ozone layer and increased risks such as skin cancer. Research led by MIT has shown that cutting