Reply to: Impact of laminar air flow on operating room contamination and surgical wound infection rates in clean and contaminated surgery

Comparison of operating room air distribution systems using the environmental quality indicator method of dynamic simulated surgical procedures

“…These guidelines also specify the use of minimum efficiency reporting value 7 in filter bank 1 and minimum efficiency reporting value 14 in filter bank 2 to deliver clean air at a specified face velocity (25-35 feet per minute [fpm]), number of ACH (20-25 ACH with 3-4 outside), humidity (30%-60%), and temperature ranges (68°F to 75°F), as well as room dimensions (20 £ 20 £ 10), ceiling grid coverage (12%-16%), and pressure maintenance (+0.01). 7 ASHRAE guidelines also recommend laminar airflow if indicated by surgical staff, which is somewhat controversial in the literature, 3,[10][11][12][13][14][15][16][17] pointing to the need to consider all design and operational aspects of the OR. Achieving laminarity in an OR is difficult due to the presence of obstructions to the air currents, and unidirectional downward airflow may be a more accurate description of the operational airflow typically achieved.…”