BackgroundThere are few data and no accepted standards for air quality in the intensive care unit (ICU). Any relationship between airborne pathogens and hospital-acquired infection (HAI) risk in the ICU remains unknown.AimFirst, to correlate environmental contamination of air and surfaces in the ICU; second, to examine any association between environmental contamination and ICU-acquired staphylococcal infection.MethodsPatients, air, and surfaces were screened on 10 sampling days in a mechanically ventilated 10-bed ICU for a 10-month period. Near-patient hand-touch sites (N = 500) and air (N = 80) were screened for total colony count and Staphylococcus aureus. Air counts were compared with surface counts according to proposed standards for air and surface bioburden. Patients were monitored for ICU-acquired staphylococcal infection throughout.FindingsOverall, 235 of 500 (47%) surfaces failed the standard for aerobic counts (≤2.5 cfu/cm2). Half of passive air samples (20/40: 50%) failed the ‘index of microbial air’ contamination (2 cfu/9 cm plate/h), and 15/40 (37.5%) active air samples failed the clean air standard