As businesses in Ontario begin to resume operations, the dental industry remains at high risk for spreading COVID-19 due to the aerosol generating nature of dental procedures and given the proximity of the operating field to the upper respiratory tract. Safely reopening dental clinics while protecting patients and staff faces significant challenges. Executing on the HVAC requirements outlined by the Royal College of Dental Surgeons of Ontario may be the most significant of these challenges – Enercare is here to help.

Clearing the Air of Aerosol (Fallow Time)

In a document presented by the Royal College of Dental Surgeons of Ontario entitled “COVID-19: Managing Infection Risks During In-Person Dental Care,” guidelines have been provided to ensure the safe opening and operation of dental offices. Below you will find key excerpts to determine the air changes per hour (ACH) for any aerosol-generating procedures.




Key Excerpts

When a patient undergoes an aerosol-generating procedure (AGP), high concentrations of droplets smaller than 5 μm (droplet nuclei) are generated that may remain suspended in the air for significant periods of time, move with air currents, and come in contact with others. This creates a risk for opportunistic airborne transmission of COVID-19, even if the virus is not otherwise able to spread by the airborne route.

Following an aerosol-generating procedure involving a patient who has screened negative for COVID-19, dentists must wait 15 minutes after completion of the clinical care and exit of each patient before cleaning and disinfection.Following an aerosol-generating procedure involving a patient who has screened or tested positive for COVID-19, cleaning and disinfection of the operatory must only be undertaken following the necessary fallow period, as described below.1


Air Changes Per Hour (ACH) Time Required for Removal or Settling of Aerosols in Minutes (99.9% Efficiency)
2 207
4 104
6 69
8 52
10 41
12 35
15 28
20 21
50 8

Fig 1. Adapted from: Centers for Disease Control and Prevention, Guidelines for Environmental Infection Control in Health-Care Facilities (2003): Table B.1. Air changes/hour (ACH) and time required for airborne-contaminant removal by efficiency.

Dentists should consult an HVAC professional to assess the existing HVAC system and calculate the actual ACH for their dental practice. Dentists may use the actual ACH to calculate a fallow time using the above table.

Dentists should retain copies of any documentation supporting the HVAC assessment and any need for engineering controls.

Options to improve ACH (and further reduce the fallow time) may be explored, including:

  1. Consulting an HVAC professional to determine whether changes to the existing HVAC system are possible to improve ACH for the dental practice.
  2. If changes to the existing HVAC system are not possible or adequate, dentists may consider the use of an in-operatory air cleaner (e.g. HEPA filtration) to increase the effective air changes per hour (eACH) for a specific operatory.
  3. If an in-operatory air cleaner (e.g. HEPA filtration) will be used to increase the effective air changes per hour (eACH) for a specific operatory, the HVAC professional must also take into account several additional factors, including:
  • any structural changes that may be necessary to contain the spread of aerosols (e.g., the addition of floor to ceiling walls or barriers),
  • the type of unit being considered (e.g. fixed versus portable),
  • the cubic feet of the operatory and airflow rate of the unit, and
  • the optimal placement and operation of the unit.

If dentists have not had the rate of air changes for their office confirmed by an HVAC professional, dentists must assume a rate of 2 air changes per hour and adhere to a minimum fallow time of 3 hours following an AGP.1




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Carrier OptiClean Benefits

  • 99.97% efficient, long-life HEPA filter removes as small as 0.3 microns
  • Standard MERV 7 or higher ore-filter
  • Minimum 500 CFM
  • Meets or exceeds the ASHRAE Standard 170: Ventilation of Health Care Facilities
  • Vertical design for smaller footprint compared to many competitors
  • Red filter indicator light alerts user when it’s time to replace a filter
  • One-year limited warranty



Why Enercare?

With over 50 years installing, servicing and maintaining HVAC equipment across Ontario, our team of experienced, highly-trained technicians are equipped with all required PPE including face shields and masks, safety gloves and goggles, as well as hand sanitizer and protective workwear. Our technicians are supported by in-house team of engineers, who create expert designs to address the unique ventilation requirements of your dental practice.

Your Assessment

For years, Enercare has offered our clients a comprehensive Validation, Inspection, Equipment Walk-Through (VIEW) program that provides business owners with an engineer-reviewed report that includes a detailed summary of the current-state and capacity of their mechanical systems. Enercare is uniquely positioned to generate HVAC assessment reporting, as well procure and install any required air handling equipment. Our report will incorporate the requirements outlined above by the Royal College of Dental Surgeons of Ontario, and we’ll make sure you fully understand your options to keep your practice up-and-running.

Call us at 1 855-321-1508 to schedule your visit today.