Many of these cases are caused by airborne exogenous organisms. Contributions from HVAC engineers have helped impede this pathway of infection, including a significant advance in operating room air distribution design included in ASHRAE's recently published Design Manual for Hospitals and Clinics.
ASHRAE is currently taking the information included in this design manual, as well as new research that enhances the modeling of operating room air distribution and infectious particle transport, and incorporating both in its new Standard 170P, Ventilation of Health Care Facilities. ASHRAE is co-sponsoring this standard with the American Society of Healthcare Engineering (ASHE).