Ammonia levels in Cache Valley (IMAGE) Utah State University Caption Ammonium nitrate is responsible for 70 percent or more of PM2.5 in Cache Valley during an inversion. Credit Taylor Emerson/USU Usage Restrictions N/A 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.