Health officials in Milwaukee, Wisconsin issued an alert on Wednesday that urged residents of the city to stop vaping due to a rash of recent hospitalizations. In a health alert released by the City of Milwaukee Health Department, cannabis consumers were warned not to vape.

“Residents are again strongly encouraged to not utilize any THC products containing e-liquid,” the health alert reads.

The health department reported that as of Wednesday, 16 individuals in 10 Wisconsin counties have been hospitalized with chemical pneumonia, an inflammation of the lungs that is caused by the inhalation of irritants. All of the patients had dabbed or vaped marijuana products in the weeks or months prior to being hospitalized, although no specifics on the cannabis vapes involved in the illnesses were given.

Commissioner of Health Dr. Jeanette Kowalik said that the risks associated with vaping cannabis or nicotine are not yet fully understood.

“We continue to learn more about the health effects associated with e-cigarettes,” Kowalik said. “As the public health authority for the city, the MHD is committed to protecting the public from the dangers of secondhand exposure.”

Milwaukee Alderman Michael J. Murphy, the co-chair of the Milwaukee City-County Heroin, Opioid, Cocaine Task Force said that despite commonly held beliefs, vaping is not a safe alternative to smoking.

“As someone who has worked diligently to eliminate access to tobacco and e-cigarettes among youth, I urge residents pay close attention to the poor health effects from using these products,” said Murphy.

CDC Investigating Nearly 200 Cases Of ‘Vape Lung’

Last week, the Centers for Disease Control and Prevention (CDC) announced that at least 193 cases of severe lung illness possibly associated with vaping had been reported in 22 states in the past two months. The first death associated to the rash of illnesses related to vaping was reported in Illinois last week.

The CDC reported that although a cause had not yet been identified, the available evidence suggests that an infectious disease is not responsible for the illnesses. All of the affected people had reported using e-cigarette or THC vaping devices, but specific products have not been identified as a potential cause of the sickness.

Thomas Haupt, a respiratory epidemiologist with the Wisconsin Department of Health Services, said earlier this month that the cause of the illnesses is being investigated.

“The only thing [we know] at this point is [they were] vaping, but we don’t know what they vaped, where they got their vaping liquids,” Haupt said. “All this needs to be determined at this point.”

FDA Also Probing Health Effects Of E-Cigs

The U.S. Food and Drug Administration is also investigating reports of negative health effects caused by e-cigarettes. Earlier this month, the agency announced that it was looking into 127 cases of seizures and other neurological effects potentially linked to the products.

“Although we still don’t have enough information to determine if e-cigarettes are causing these reported incidents, we believe it’s critical to keep the public updated on the information we’ve received based on the agency’s initial request for reports earlier this year,” Dr. Ned Sharpless, the acting FDA commissioner, said in a statement.