BEAUFORT, S.C. (AP) — School officials in a South Carolina district say potentially hazardous mercury vapor has been seeping from gym floors at four schools.

The Island Packet of Hilton Head reports officials with the Beaufort County School District said rubber gym floors at Hilton Head School of the Creative Arts, Beaufort Middle School, Robert Smalls Academy and Islands Academy each tested positive for mercury vapor.

Mercury vapor levels are far below accepted standards from the Agency for Toxic Substances and Disease Registry when the air conditioning is on. When it's off, the levels to a point of significantly more concern based on agency standards.

The manager for a consulting firm hired by the district for air-quality testing told board members Friday that there was "no reason for immediate concern or panic."