SIOUX CITY, Iowa (AP) — New concerns are being raised about the air quality inside a northwest Iowa jail that was built on the site of a former gas station. The Sioux City Journal reports officials are looking at ways to address the concerns at the Woodbury County Law Enforcement Center. Health officials have been monitoring conditions for years with regular tests, but a test performed in the building last fall showed elevated levels of benzene.

Officials thought the problems were solved in 2003 when an air filtration system was added, but the recent tests suggests more steps might be needed. Matthew Graesch with the state Department of Natural Resources says officials are looking for a better long-term solution to make sure petroleum vapors won’t cause problems.