Negative Pressure Rooms – Air Systems

Airborne infection precautions for patients due to aerosol generating procedures are not always possible in most dental settings as dental operatories are not always designed or equipped with negative pressure rooms. An negative pressure room should be used if aerosol generating procedures are performed on known or suspected COVID-19 patients.

What is an Aerosol Generating Procedure (AGP)?
Air polishers, ultrasonic scalers, air abrasion units and the use of turbine hand pieces are all examples of AGP’s and produce the most visible aerosols.

Negative pressure rooms should also be used for the care of patients with pathogens transmitted airborne such as: tuberculosis, measles, varicella.

If emergency dental care is necessary for a patient who has, or is suspected of having COVID-19, a negative pressure room, with HEPA filtration and the use of required Personal Protection Equipment (PPE) is recommended by the CDC/OSHA/HHS for any person entering the room should be followed for patients undergoing aerosol generating procedures (AGP).

What happens during a AGP?
Particles become aerosolized from the operative site as a result of the action of the ultrasonic vibrations, rotary instrument, or water sprays combined with compressed air. Contaminated aerosols are also produced during dental procedures when there are no visible aerosols.

What is a Negative Pressure Room?
An negative pressure room air system is a single patient care examination room or operatory used to isolate persons with a suspected or confirmed airborne infectious disease, such as COVID-19, tuberculosis, measles or varicella. Environmental factors are controlled within the room and surrounding area to minimize transmission of infectious disease from person to person associated with coughing or aerosolizaton of fluid.

TMI® Air Barrier Testing is able to convert existing dental operatories and medical examination rooms into CDC compliant negative pressure rooms.

TMI® engineers a solution specific for each examination room or operatory after initial assessment that induces a negative pressure differential of -2.5 Pa and 12 air changes per hour (ACH) for compliance to CDC/OSHA guidelines. Room doors should be kept closed except when entering or leaving the room, and entry and exit should be minimized.

TMI® provides additional safety measures and installs monitoring devices for negative air pressure, air flow and HEPA filter pressures and provides on-site training to medical and dental staff. Devices are to be monitored and documented for the correct negative pressure at all times.

To Learn More About Interim Infection Prevention and Control Guidance for Dental Settings During the COVID-19 Response please visit the following link:

To Learn More About Interim Infection Prevention and Control Recommendations for Patients with Suspected or Confirmed Coronavirus Disease 2019 (COVID-19) in a Healthcare Settings please visit the following link:

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