Urban moss (IMAGE) Oregon State University Caption Orthotrichum lyelli, a type of moss typically found growing on trees, is an effective air monitoring system because it has a wide surface area to collect contaminants that settle out of the air around it. Credit Alyssa Shiel, Oregon State University. Usage Restrictions Media use only 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.