A foul odor plagued the city of Kings Mountain this winter as cold weather unearthed a long-submerged gas. International mining company Albemarle is working to restart the mine after a four-decade hiatus to extract lithium for rechargeable batteries.
City officials started investigating an eggy smell in early December 2024. Albemarle confirmed that, yes, the pit lake did smell, and state regulators determined that the rotten odor came from hydrogen sulfide gas. Cold weather had cooled the surface of the Kings Mountain pit lake, causing the surface of the lake to sink, and the bottom to rise, releasing the trapped gas beneath.
Albemarle installed additional air monitors near the Kings Mountain pit lake after state regulators encouraged the mining company to measure hydrogen sulfide gas exiting the lake. At least some of the monitors were placed downwind of the lake.
When determining the risk a particular chemical poses, state regulators weigh the length of exposure against the concentration. The minimum amount of hydrogen sulfide that the average person can inhale for up to two weeks without adverse health effects is 70 parts per billion. The human nose can detect the trademark rotten-egg smell of the gas at levels far below that, and the nose desensitizes to it at high levels, meaning the smell test is not the best metric for risk.
Albemarle collected data between January 19-28. Although at least some monitors detected hydrogen sulfide daily, the highest levels peaked well below the minimum risk level. In other words, the smell was a persistent nuisance but not a threat to residents’ physical health.
Still, state regulators said they will continue monitoring air quality at the mine. They encouraged residents who notice a bad odor to call the Department of Environmental Quality’s Mooresville Regional Office.
The North Carolina Department of Environmental Quality issued the following statement on the smell:
“Albemarle will continue to submit air quality data for DAQ to review to ensure health-based levels are maintained. DEQ is and will continue to be in communication with state health officials, local officials and the permittee about this. DEQ continues to engage with the facility as it explores technical solutions to mitigate odors in the community."
Kings Mountain residents who notice objectionable odors in their community should call DEQ’s Mooresville Regional Office at 704-235-2100 and ask for someone at the Division of Air Quality.”
