Objectives: We longitudinally observed and assessed the impact of the operating room (OR) staff movements and door openings on surrogates of the exogenous infectious risk using a new technology system. Design and setting: This multicenter observational study included 13 ORs from 10 hospitals, performing planned cardiac and orthopedic surgery (total hip or knee replacement). Door openings during the surgical procedure were obtained from data collected by inertial sensors fixed on the doors. Intraoperative staff movements were captured by a network of 8 infrared cameras. For each surgical procedure, 3 microbiological air counts, longitudinal particles counts, and 1 bacteriological sample of the wound before skin closure were performed. Statistics were performed using a linear mixed model for longitudinal data. Results: We included 34 orthopedic and 25 cardiac procedures. The median frequency of door openings from incision to closure was independently associated with an increased log10 0.3 µm particle (ß, 0.03; standard deviation [SD], 0.01; P = .01) and air microbial count (ß, 0.07; SD, 0.03; P = .03) but was not significantly correlated with the wound contamination before closure (r = 0.13; P = .32). The number of persons (ß, −0.08; SD, 0.03; P < .01), and the cumulated movements by the surgical team (ß, 0.0004; SD, 0.0005; P < .01) were associated with log10 0.3 µm particle counts. Conclusions: This study has demonstrated a previously missing association between intraoperative staff movements and surrogates of the exogenous risk of surgical site infection. Restriction of staff movements and door openings should be considered for the control of the intraoperative exogenous infectious risk.