A health hazard evaluation (HHE) was requested by management at the neonatal intensive care unit (NICU) at Exempla St. Joseph's Hospital in Denver, Colorado. The request concerned possible exposures to natural rubber latex (NRL) proteins. Employees reported rhinitis, sneezing, rash, watery eyes, and aggravation of allergic symptoms. A reservoir of dust was found within the NICU; exhaust from the central vacuum cleaning system was leaking into the ceiling plenum of an area adjacent to the NICU. The system exhausted vacuumed carpet dust into the ceiling plenum, rather than to the outside, as designed. The use of pressure measurements and carbon dioxide tracer gas demonstrated that a potential pathway existed for the movement of airborne dusts from the affected plenum to the adjacent plenum over the NICU. Two air samples, six surface samples, and two bulk dust samples were collected. Concentrations of NRL ranged from below the limit of detection [<1 allergy units (AU) per milliliter of extracted sample] to 4.2 AUs. Eight of the ten samples were in a range considered to be trace concentrations. The two NRL air samples were reported at less than the limit of detection and 1.8 AU. No mechanical or maintenance deficiencies and no visible microbiological contamination were identified in the air handling unit serving the NICU. A water leak in the NICU was identified, and remediated by hospital personnel.