HAMILTON COUNTY, Ind. -- Ooh that smell. Can't you smell that smell?
Hundreds of calls came in Sunday afternoon about a natural gas-like odor in the area of Carmel and northern Marion County.
The Hamilton County Emergency Management Agency said gas monitors were used and no natural gas was detected.
The source of the smell was mercaptan, a non-deadly chemical additive that is infused into odorless natural gas so that it is detectable. While the additive itself isn't overly dangerous, it can be an irritant.
Dispatch is on phone with Vectren. Calls are pouring in, East of College from 96th to 131st. We have multiple trucks investigating.
— Carmel Fire PIO (@CFD911runs) January 8, 2017
The cause of the mercaptan release was due to a frozen pipe that led to a malfunction in the air handling system at the industrial refinery Heritage Crystal Clean, Erin Rowe, the director of HCEMA, released in a statement Monday.
Heritage, which is located at 560 W. Old Raymond St., produces a lubricant base oil at its Indianapolis plant. The refinery had a similar incident in July 2016, when mercaptan was accidentally released, prompting the evacuation of three buildings on Butler University's campus.
READ MORE | Gas odor detected across Marion, Hamilton counties
Call 6 Investigates found Heritage Crystal Clean was inspected by IDEM in 2016 after complaints about white ash falling into neighborhoods.
The plant manager at HCC said the company installed a screen on the stack associated with the ash-like emissions.
The Indiana Department of Environmental Management says lab reports on the ash substance were, "well below the NIOSH recommended exposure limit thresholds."
If you feel like you have been exposed to mercaptan gas, you should immediately move to a well-ventilated area and call 911 if you experience nausea, eye irritation, difficulty breathing or irritated skin.
