When the Phillips Collection, genteel aunt of the city's art museums, undertook a $2 million renovation three years ago, its directors touted a new high-tech climate control system designed to keep the air as fresh as that in Monet's garden.

But since being turned on last December, the system has left the Phillips tainted with decidedly ungenteel aromas, and, occasionally, eye-watering fumes.

Charles Olin, an expert in painting restoration and preservation who has worked on several Phillips masterpieces, including Renoir's "Luncheon of the Boating Party" said sulfur dioxide apparently emanating from the system's humidifier poses no real threat to the collection's paintings.

But Laughlin Phillips, the collection's director, confirmed that "certain museum . . . guards" have experienced "a variety of allergic-type symptoms, including respiratory difficulties and eye-smarting."

According to museum assistants, the Phillips consulted the Occupational Safety and Health Administration in late January or February to investigate both the odor, described as an oil-like smell, and employe complaints.

But, they said, nothing was found and a private consultant was called in. Museum assistants said the consultant removed the climate system's water softener, and the odor and allergic reactions among employes abated somewhat; but a month and a half later, during April, the smell returned together with employe symptoms, and anxiety about the situation increased.

Phillips said affected workers were encouraged to take time off and several did, but he noted that "the museum was never asked to turn the system off because there was no identification of a [health safety] problem . . . "

Sulfur dioxide, when released into the atmosphere, can combine with moisture to form sulfurous acid and then sulfuric acid, which in the past has corroded marble buildings and even pitted metal statuary in industrial settings.

But Olin noted that the pigment in oil paintings at the Phillips is mostly isolated from the atmosphere because the surfaces have been waxed or varnished.

Phillips said the climate-control system was intended "to maintain the relatively constant levels of humidity required for the well-being of works of art. He said the museum's 18 museum assistant positions are filled by "about 40 people" and that "at least a third" reported allergic symptoms.

"Yet others, the majority of us," Phillips said, "haven't noticed anything except an occasional odor."

He said virtually completed tests by Biospherics Inc., a Rockville firm, indicate the subsequent problem resulted from lubricating oils used to thread pipes in the air duct system.

Gary Gottfried, director of Biospherics' lab division, said an analysis of hydrocarbons found in the steam system showed a trace of aldehydes, a common organic compound formed when hot oil oxidizes, and which can be an irritant to some people.

All that was needed to solve the problem, he said, was "simply to flush out the system with steam. We did not find any chemicals or other contaminants that posed a health risk to the individual," he said.