Seattle Children’s hospital has closed several operating rooms that tested positive for a type of mold that can cause health complications.

A Seattle Children’s spokesperson said Tuesday that air tests detected Aspergillus in several operating rooms and equipment storage rooms on the hospital’s main campus last weekend.

Aspergillus is a common mold indoors and outdoors, but it can cause people with weakened immune systems or lung to get sick, according to the Centers for Disease Control and Prevention. Related health problems include allergic reactions and lung infections.

"The idea is that the Aspergillus in the air could settle in the wound while it is open during surgery and cause an infection, that is our primary concern," said Seattle Children’s Division Chief of Pediatric Infectious Disease Dr. Danielle Zerr.

Some surgical patients have been moved to the Bellevue campus, and other surgical cases have been postponed or diverted. Chief Medical Officer Dr. Mark Del Beccaro said they are postponing 20 to 50 cases a day.

The hospital said it will also perform work in areas of the hospital that are clear of Aspergillus.

“Until we find the source we are being very conservative about even doing cases that are low risk," said Dr. Beccaro. He added that the risk of infection is “incredibly small.”

Seattle Children’s is working with an outside industrial hygienist to figure out how the mold got there and how to mitigate it. The operating rooms will stay closed until the hospital is sure they are clear of the mold.

Patients who may have been exposed will be contacted, and if patients have questions, they can contact the hospital at (206) 987-1061.