BOSTON (CBS) — The Massachusetts Department of Public Health is warning that reduced water use in empty office buildings can increase the risk of mold and the bacteria that causes Legionnaire’s disease.

The department posted this warning on its webpage today: “The temporary shutdown or reduced operation of a building and reductions in normal water use can create hazards for returning occupants; these hazards can include mold and Legionella. After a prolonged shutdown, building owners and employers should ensure that their building does not have mold and that the water system is safe to use to minimize the risk of Legionnaires’ disease.”

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Dr. Paul Sax, the clinical director of the Division of Infectious Diseases at Brigham and Women’s Hospital, said that while Legionella bacteria is rare, there is a risk.

“This particular bacteria likes to live in stagnant water, and so it finds areas of stagnant water and starts to multiply,” he explained.

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Sax said there is a risk in office plumbing and air conditioning if they haven’t been circulated since the shutdown back in March.

“If, for example, an air condition system or plumbing system…is contaminated with Legionella and ends up not being cleaned out or changed frequently enough, then it can then be inhaled by a person who then develops pneumonia,” he explained.

The state also listed the Centers for Disease Control website for information on what building owners can do to reduce the risk.

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