The House Veterans Affairs Committee is investigating the beleaguered Northport Veterans Affairs Medical Center and will hold a field hearing on Long Island next month, a committee staff member said on Tuesday.

“The scope of the investigation includes, but is not limited to,” the closing of the hospital’s operating rooms for months after sand-size black particles began falling from air ducts, the staff member said, and has been continuing for more than a month. The closing of the operating rooms was reported by The New York Times in May.

In a July 29 letter to the veterans affairs secretary, Robert A. McDonald, Representative Jeff Miller, Republican of Florida and the committee’s chairman, questioned the management of the hospital. In the letter, Mr. Miller noted “a prevalence of sole source and ostensibly competitive, one-bid facilities contracts, with a substantial amount of money going out the door for maintenance, but seemingly poor results.”

“The most troubling aspect of the whole situation,” the letter added, was that the management at the Northport center “reportedly became aware of the problem in mid-February yet took no effort to notify the public or Congress until after the numerous media reports emerged.”