Determine whether operating room air filtration and sterilization with the ActivePure system reduces a composite of serious surgical site infections, infection-related complications, and death within 30 days after surgery.

The investigators primary goal is thus to determine whether supplemental filtering and sterilizing operating room air reduces a composite of serious surgical site infections, infection-related complications, and death within 30 days after surgery. The primary outcome will be restricted to inpatients. However, outpatients will be simultaneously enrolled given the trial's cluster design. Sample-size is based on our primary inpatient analysis, N= 66,273 inpatients. Available outpatients will be included for analysis of our secondary outcome which includes both inpatients and outpatients.

Inclusion Criteria:

• All patients in designated adult operating rooms
• American Society of Anesthesiologists physical status 1-4.
• Surgery lasting at least 1 hour.

Patient level data will be shared collaboratively. Sharing will require approval of the trial steering committee and appropriate institutions approvals and data-sharing contracts.

1 year after publication of the main trial paper.

Contact principal investigator.

Identical-looking test devices are either active or inactive. None of the investigators, clinicians, patients, or outcome assessors knows which are which.