Multiple public safety agencies are investigating reports of an unknown odor in Delaware and Franklin counties.

Multiple public safety agencies are investigating reports of an unknown odor in Delaware and Franklin counties.

According to the Delaware County Office of Homeland Security and Emergency Management, the county's 911 center has received multiple calls about an odor this morning, Dec. 10. A news release from the agency states residents are reporting the smell along the U.S. Route 23 corridor between Delaware and the southern county line.

Multiple area fire departments have sent personnel out to investigate the complaints.

According to a report from The Columbus Dispatch, Columbus firefighters and Columbia Gas of Ohio employees are investigating similar reports in Franklin County.

According to the Environmental Protection Agency, the region is experiencing a temperature inversion, which may explain the odor. In a temperature inversion, warmer air traps colder air near the ground, which can prevent odors and pollutants from dispersing.

An air-quality forecast from the EPA shows calm winds also may be contributing to the problem of pollutants hanging over the area.