Air contamination for predicting wound contamination in clean surgery: A large multicenter study.

•We assessed correlations between 2 types of air sampling and wound contaminations.•We included 13 operating rooms of cardiac and orthopedic surgery in 10 health care facilities.•A strong correlation exists between air particle counts and microbial contamination.•Particle counting is a good surrogate of airborne microbiologic contamination.•Laminar airflow was associated with decreased air microbial contamination.