Figure 1. A diagram of the second floor of the University of Michigan School of Dentistry.

Note: Downward diagonal shaded areas (1) indicate the undergraduate patient clinics where the experiment was conducted. The closest oxygen tank is located in the narrow horizontal shaded area (2), which is the dispensing location for dental instruments and materials. Oxygen tanks are also located in the outpatient oral surgery clinic, outlined in black (3). There are two additional undergraduate patient clinics on the third floor, located directly above the diagonal shaded areas (1) outlined in the diagram, that follow an identical design with the exception of the oral surgery department.