U.S. scientists said that global warming might delay the recovery of stratospheric ozone in some parts of Earth, negatively affecting public health, according to UPI. Researchers led by Johns Hopkins University Professor Darryn Waugh said they discovered increasing greenhouse gases could delay, or even postpone indefinitely, the recovery of stratospheric ozone in some regions of the Earth, including Australia and Brazil, possible taking a toll on public health. They said climate change could cause variations in the circulation of air in the lower stratosphere in tropical and southern mid-latitudes, preventing ozone levels from ever returning to levels present before decline began, even after ozone-depleting substances have been eliminated from the atmosphere. "Global warming causes changes in the speed that the air is transported into and through the lower stratosphere (in tropical and southern mid-latitudes)," said Waugh. "You're moving the air through it quicker, so less ozone gets formed.