(KRON) — Residents who live or work near the Crockett Wastewater Treatment Plant are being advised to take precautions due to elevated levels of hydrogen sulfide in the air. In a press release issued Friday, Contra Costa County Health Services advised people to take steps to stay safe.

Gas levels detected in the air near the plant on Friday by the Bay Area Air Quality Management District were determined to be high enough to affect the health of anyone exposed to it for a long period of time. Exposure could result in symptoms that include headaches, nausea and irritated eyes, according to CCH.

The presence of the gas is related to an ongoing operational issue at the plant, which is located at 1801 Dowrelio Road. According to the press release, there have been several complaints about strong odors which are being investigated by BAAQMD. Friday was the first day the detected levels were high enough to cause a public health concern.

While hydrogen sulfide is recognizable for its similarity to the smell of rotting eggs, smelling it is not always an indicator that levels in the air are high enough to be a health risk, the press release says.

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People who are near the plant and experiencing symptoms are advised to consider leaving the area if possible, or going inside and shutting all doors and windows. Anyone with serious symptoms is advised to contact their health care provider.

The air in Crockett is being monitored by Contra Costa Health and updates will be posted at cchealth.org.

The press release advises that carbon air filters may be effective at reducing hydrogen sulfide levels but that masks do not offer effective protection.