The Biosciences Research Building at the John A. Burns School of Medicine in Kaka'ako was briefly evacuated yesterday morning after two security guards complained of chemical fumes coming from a second-floor laboratory room.

The apparent source of the odor was an uncovered beaker containing bleach used to dispose of tissue culture experiments, a standard procedure, said medical school spokesman Gregg Takayama.

"The odor was traced to the tissue-culture room on the second floor, where a beaker containing bleach had been placed in the sink," Takayama said. "A lab worker put the bleach in the beaker and left it uncovered."

A city ambulance was called to the medical school about 5:30 a.m. and was met by two medical school security guards, a man and a woman, who reported feeling dizzy and slightly nauseated, said Bryan Cheplic, a spokesman for the city Emergency Medical Services operation.

While paramedics were treating the guards, a man employed by a nearby car dealership also reported experiencing similar symptoms. He had walked by the school earlier.

All three were taken by city ambulance to The Queen's Medical Center and were reported in stable condition on their arrival, Cheplic said. They were released from the hospital a few hours later.

About 250 medical students attend classes at the school, Takayama said. He said Samuel Shomaker, the interim dean, ordered classes canceled about 9 a.m. only to have a firefighting team sound the all-clear about 30 minutes later. Because most of the students had not yet learned that classes were canceled, a decision was made to resume the classes, Takayama said.

Fire Capt. Kenison Tejada said a hazardous-materials response team searched inside the school's research building trying to identify the source of the noxious odor "but didn't get a positive reading for anything."

However, Tejada said, meters did indicate a low oxygen level in the tissue-culture lab room. Compressed nitrogen and oxygen are used in the lab and may have contributed to the slightly lower oxygen level, he said. Hazmat team members also reported a faint bleach scent coming from the lab area.

Takayama said bleach is used to sanitize glass containers in the lab when researchers finish culturing tissue in the containers. He said the security guards apparently were overcome by the bleach fumes when they entered the room.

Takayama said the school's vent system had been partially shut overnight, apparently contributing to the buildup of bleach fumes. He said each of the rooms in the research building is vented separately to prevent cross-contamination. The vented air is filtered before it is discharged outside the building.

Reach David Waite at dwaite@honoluluadvertiser.com.