They've ruled out dust...and spores that could leak from the ventilation system. But Monmouth County officials remain baffled over what prompted health reactions in nearly 80 people at the County Courthouse since Friday, and they're keeping it closed for the second straight day.

People were treated on site and at Centrastate Medical Center in Freehold for symptoms including breathing difficulties, rashes, runny noses and even chest pains. Evacuations took place Friday and Monday.

The consensus is that the villain is airborne - but its identity remains mysterious.

County Public Information Director Bill Heine says that as early as Monday night, New Jersey State Police Hazmat squads fanned out through the building to assess the air quality. "They tested for 25,000 different compounds," he says, "and found nothing."

Interestingly, Heine notes that crews who cleaned the building and teams who tested air and surfaces during the weekend (when floral arrangements seemed to be the culprits) and Tuesday (when they were ruled out) wore no protective outer gear such as hazmat suits, and reported no symptoms.

"This could be one of those things that builds up," Heine suggests. "It could be something that develops through prolonged exposure, but we just don't know."

The next round of testing, says Heine, becomes more intricate. "We're gonna do some testing for more common allergens," he explains. "Things that can come from plants or animals , or items that can be found on people's desks." After the testing, the entire building gets another cleaning.

Heine adds that the protocol of a state-operated function in a county-owned building brought into play not only county health officers and sheriff, but also state judiciary staffers and the state police.