At least 10 patients at an Oregon hospital were burned because staff didn't replace filters on lights in three operating rooms, according to an article on The Columbian website.

Staff at Silverton Hospital changed diffusers on the halogen lights in September 2013 but left out the filters, hospital officials said. 

The first cases of skin burns came to the hospital's attention the following June and a hospital investigation pinpointed the cause five months later in November, the article said.

Halogen lamps emit ultraviolet light and must have filters. The filter is often incorporated into the bulb's glass, but some lamps require separate ones.

It took several months to figure out the cause of the burns, because the hospital initially looked at more common culprits: solutions used to prep skin before surgery, bandages or dressings used after surgery, and cautery devices used to stop bleeding during surgery.

Read the article.