Pollution (IMAGE) Intermountain Medical Center Caption Outdoor air pollution is a major contributor to indoor air pollution -- but high-efficiency particulate air (HEPA) filters used in the home significantly reduce fine-particulate matter in the air compared with non-HEPA air filters, according to new study. Credit Intermountain Medical Center 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.