Officials said small amount of formaldehyde leaked through a box onto a chair on the fourth floor in an office at the CancerCare building on McDermot Avenue Thursday afternoon.

An evacuation of one floor was put into place as part of protocol. Fire crews and the haz-mat team were also on scene.

Five staff members were checked over as a precaution. No further treatment was required.

The evacuation did not interrupt patient care, said officials.

A few patients in the prostate clinic were moved to another wing as precaution and were checked over and all deemed fine, said officials.