(CNN) Children's Medical Center Dallas last week relocated 28 patients after routine air tests showed higher-than-normal levels of Aspergillus and Penicillium molds, according to Virginia Hock, a Children's Health spokesperson.

When mold results were identified on December 4, patients were moved from the cardiac intensive care unit at Children's Medical Center Dallas to other parts of the facility "out of an abundance of caution," Hock said.

No patients have become infected and none have experienced any health effects as a result of the mold, Hock said. Aspergillus and Penicillium are common indoor molds, according to the US Centers for Disease Control and Prevention, but mold can be dangerous for people with weakened immune systems or lung disease.

"We proactively took steps to reduce any potential patient risk," Hock said.

Get CNN Health's weekly newsletter Sign up here to get The Results Are In with Dr. Sanjay Gupta every Tuesday from the CNN Health team.

Hock said no previous tests at Children's Medical Center Dallas showed mold outside the expected ranges. There is an ongoing investigation into last week's test results.

Read More