Persistent Free Radicals (IMAGE) American Chemical Society Caption Persistent free radicals, a newly discovered air pollutant, could have effects similar to cigarette smoke, Louisiana researchers say. Credit H. Barry Dellinger, Louisiana State University Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.