Oil wells in Signal Hill, California (IMAGE) Stanford University Caption Oil wells operating in Signal Hill, a city in Los Angeles County, California. Researchers found that drilling and operating wells emits harmful levels of pollution that may affect the health of nearby residents. (Image credit: David Gonzalez) Credit David Gonzalez Usage Restrictions With credit 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.