Purpose: A third of the global disease burden requires surgical therapy, yet in disaster-affected areas and lower-middle income countries, 5 billion people have little or no access to safe surgical care. We develop, evaluate, and aim to deploy a new technology to help increase access to safe surgery.Methods: We conducted a needs assessment, then used iterative prototyping to incorporate stakeholder feedback and testing of all components. Proof-of-concept testing of the prototype entailed setup over a mannequin and using a particle counter to evaluate ability to provide a contaminant-free sterile field.Results: Our prototype shrinks the scope of the sterility challenge from the room to the critical space immediately over the incision. Users seal the modular system of sterile clear containers over the patient and operate via ports. An integrated airflow system controls enclosure conditions. Everything folds for rapid deployment. Testing demonstrates superior environmental control compared to standard operating rooms, including setup time, time to surgical site sterility, resistance to active contamination, and air changes per hour.Conclusions: Our results indicate that it is possible to provide state-of-the-art levels of sterility during surgeries even in austere settings, by using a low-cost, ultraportable, modular system co-developed with key stakeholders.