The coating had not been completely removed in the far corners of the sinks during classroom renovations, according to a letter dated Thursday and sent by Hale'iwa principal Diane Matsukawa to faculty and staff.

Summer classes that were being held in two of the rooms were relocated until the sinks could be removed, Goya said. Neither of the summer classes was in the room where the coating flake fell off, she said.

Asbestos fibers can be dangerous if they become airborne and are inhaled, according to the federal Environmental Protection Agency. The fibers increase the risk of contracting lung diseases such as asbestosis, lung cancer and mesothelioma.

Another asbestos incident sparked an uproar last year at King Intermediate School in Kane'ohe, after workers discovered asbestos when they began sanding the exterior of two buildings to prepare them for painting.

The campus was closed after teachers and parents expressed alarm, and the substance was removed. Most of the work was done over the Christmas break, but required students to miss five school days.

School officials said that incident was a reminder of the potential health hazard at nearly all of Hawai'i's schools, public or private. Most were built before 1989, when the EPA banned most products containing asbestos.

Asbestos does not pose a health threat as long as it is contained, officials have said. Each school is required to maintain an asbestos management plan and to inspect facilities every three years while conducting surveillance checks of known or suspected asbestos-containing building material every six months.