Figure 1.

Carbon dioxide (CO₂) levels during dental treatment procedures in operatories with low and high mechanical ventilation. (A) Significant CO₂ accumulation occurred in a room with low ventilation (air change per hour [ACH] = 3.9) and multiple persons in the room during clinical teaching activities for dental implant surgery. CO₂ level is associated with ventilation rate in rooms with the same number of persons. Peak CO₂ level reached 1,100 ppm in the room with 3.9 ACH (B) but stayed under 700 ppm in the rooms with 35 ACH (C).