COLUMBUS, Ohio (WCMH) – Parts of the Columbus area are under a nitrate advisory, and that includes several hospitals.

In the cafeteria and above water fountains at Grant Medical Center, there are signs posted warning people not to drink the tap water.

“Nitrates are things that we consume as adults in our food pretty regularly,” said Dr. Michael Ezzie, a pulmonary and critical care doctor who is the director of medical education. “For most of us, when we eat nitrates, we break them down in our digestive system, in our gut and our body processes them pretty regularly.”

The concern is for pregnant or breastfeeding women and for infants younger than six months. For those groups, bottled water is advised for drinking or food preparation.

Ezzie noted that this is not the first time some of these hospitals have been under a nitrate advisory. He said it also happened for about two weeks in June 2015.

Ezzie said that nitrates in the tap water can cause breathing problems in infants younger than six months.

“The breakdown is an effect on the blood system and carrying oxygen,” Ezzie said. “So the term that this causes is blue baby syndrome, where they become-they have difficulty breathing and really need medical attention very quickly, because it is reversible.”

At Grant and other affected hospitals and offices in the OhioHealth system, there is now bottled water on hand for patients and workers. Ezzie said that will be the case as long as the advisory is in effect.

Activated carbon filters, such as a Brita pitcher, will not remove nitrates. Neither will boiling the water, which Ezzie said can actually increase the level of nitrates.What others are clicking on: