Best Practice on Ventilating your Dental Practice
Mitigating against the risk of virus transmission has been a top priority for dental practices since the onset of the Coronavirus pandemic and most practices will have already taken steps to improving ventilation accordingly.
As we begin to see restrictions eased and patient confidence returning, air quality will continue to be in the spotlight as dental practices work to manage the oncoming rise in aerosol-generating procedures (AGPs) and the risk factors involved safely and efficiently.
Having the right ventilation in place is critical to reducing the risk of virus transmission, shortening fallow time, and ultimately treating patients at a quicker rate and in a safer environment.
What is fallow time?
Fallow time is a concept that was introduced by England’s Chief Dental Officer (CDO) to minimise aerosol transmission of Covid-19.
It is essentially the downtime in the dental surgery following an AGP, in which the droplets and aerosols produced from the procedure are removed from the air. During this time no patients should enter the room and any staff who do should wear FFP2/3 masks and PPE.
Calculated from the point the AGP ceases, how long this fallow time lasts is in large part determined by what ventilation is in place.
Along with a few other methods, having a ventilation system that provides a higher number of air changes per hour (ACH) is key to shorter fallow time. FGDP have a fallow time calculator that is free to use and is built on the latest recommendations.
Maximising air changes per hour
By increasing the number of air changes per hour in a treatment room from 6 to 10, fallow time can be reduced by up to 66%. Rooms with only six ACH are required to allow a fallow time of at least an hour, while those with 10-12 air changes can require as little as 20 minutes, according to the CDO guidelines.
Ventilation systems that bring clean air into the room and take the stale air out should be set to maximise the fresh air flow rate to help achieve this target and be used in combination with windows and air conditioning for the best possible results.
The ACH capacity of your existing ventilation system can be determined by checking with the manufacturer or a ventilation engineer.
Whichever type of systems your practice currently relies on, there are several checks and potential upgrades that should be considered to ensure your ventilation and disinfection is as effective as can feasibly be.
External suction units
External extra-oral suction units are a quick and convenient clean air solution that can be wheeled into any treatment room to make an immediate impact during AGPs.
Suction units, such as the BA Optima EOS 350, effectively capture droplets and airborne aerosols produced from dental treatments at the source and the sterilise these viruses and bacteria trapped by the filter with medical grade double UVC lamps.
Airtight casing prevents contaminants from escaping, while the exhaust air released from rear-mounted air vent at top of system prevents dust and contaminants blowing up from floor surfaces.
The BA EOS 350 Extra-Oral Suction Unit is low noise, lightweight in design and easy to move around the room. It has an expected system lifetime of 8,000 hours of continuous use and comes with a control panel that automatically reminds you when a filter needs replacing.
Natural ventilation in dental practices
Natural ventilation in the form of open windows should be utilised more than normal now in order to improve ventilation in treatment rooms and throughout the practice. If possible, open your windows at least 15 minutes prior to occupation and keep them ajar as much as possible during opening times. Remember, even just a small opening can delivery significant ventilation.
Naturally, you need to be mindful of the weather outside and any opening of windows should be a careful balance between infection control and the overall comfort of the patient. If appropriate, consider rearranging seating to mitigate this.
To maximise airflow, open both high and level windows when available as this will create a more efficient air flow. When it’s colder outside, prioritise the window higher up as the incoming air will warm as it flows down into the room.
For rooms with windows on only one side, consider the additions of a fan or air purifier to redistribute and clean air across the entirety of the room.
Pros of natural ventilation
- Generally more economical - lower operational and maintenance costs
- Can be more energy efficient
Cons of natural ventilation
- Difficulty predicting and controlling airflow as dependent on outside conditions
- Variable ACH rate
Mechanical ventilation in dental practices
Mechanical ventilation uses a system of fans and ducts to take the stale air out of a room, bring clean air into a room, or both (supply and extra ventilation). All three of these mechanical ventilation types are likely to produce a more stable air change rate versus natural ventilation regardless of variable wind and ambient temperature.
For the best results, CIBSE guidance advises supply and extract systems to be set to a nominal speed an hour before the room is being used and then set to switch to a lower speed an hour after the room is no longer in use. When the room is in use, systems should always be set to maximise the fresh air flow rate to help achieve the shortest fallow time possible.
Solutions, such as a mechanical ventilation with heat recovery system (MVHR), will not only provide separation of incoming fresh air and outcoming toxic air with no cross contamination, but will also recover heat that would normally be lost to keep the room at a comfortable temperature. Most modern MVHRs can be set to guarantee 10 ACH which is the equivalent of 400 cubic metres of clean air entering into the treatment room every day.
For existing ventilation systems, remember that its efficacy will have reduced over time, so it is important to ensure correct maintenance has been carried out to guarantee you’re getting the best possible air circulation.
Pros of mechanical ventilation
- Easier to predict and control
- More stable air change rate
- Filtration systems can remove harmful pollutants
Cons of mechanical ventilation
- Cost of installation and maintenance
- Potential noise of equipment
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