Inflamed skin illustration (IMAGE) Northwestern University Caption Inflamed skin shows free radicals (green) within the skin. ROS are "reactive oxygen species," or free radicals. Credit Yu Chen, Northwestern University Usage Restrictions Credit accordingly. License Original 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.