The key to reducing fallow time

surgery empty for fallow time

I have good news! Dependent on circumstances, you can now get your fallow time down to just 10 minutes. And the Faculty of General Dental Practice UK and College of General Dentistry agree, writes Jim Hague.

In early October, the Faculty of General Dental Practice UK and College of General Dentistry updated their guidance on the implications of COVID-19 for the safe management of general dental practice. The guidance incorporated the reduced ‘fallow’ times recommended by the Scottish Dental Clinical Effectiveness Programme (SDCEP) (the full document is available at https://bit.ly/3iUOsdP).

In practical terms, this new guidance means there is a way for dental teams to reduce their fallow time to just 10 minutes. If the set-up you have makes the surgery safe in that period.

The natural question to ask then is – what set up do you need to incorporate a fallow time of 10 minutes safely and effectively?

This has the potential to seem complicated. However, the SDCEP created a handy flow chart to help you assess exactly where you are and what you might need to do to reduce your current fallow time (see p44 of the above-mentioned guidance). And it really is straightforward.

In the top 10

In essence, it’s all about the number of air changes per hour in the surgery.

Start by calculating the volume of your room in metres (it’s as easy as length x width x height). Then look at your existing flow rate (look up the make/model of extractors or air purification units in your surgery for their flow rates online. Or ask your equipment supplier for assistance). The flow rate divided by the volume of the room will give you your air changes per hour (ACH).

Note that you should halve the air purification element of the flow rate. Unless you have a system that is independently validated; then you can apply 100% of the ACH now.

Following the flow chart – choose the appropriate ACH range. Just 10+ is the top bracket now. Then work your way down.

Are you using high-volume suction? Working with a rubber dam? Lesser or greater than a five-minute aerosol generating procedure? Then you will reach your appropriate fallow time (between 10 and 30 minutes).

If you are at above a 10-minute fallow and wish to reduce it, then an easy solution is to consider additional ventilation or air purification until the total flow exceeds 10x your volume.

An important note at this juncture. You need to certify that your high-volume suction system is operating at the right flow rate.

This will protect you from potential liability, and stressful and costly negligence claims.

Equipping the surgery

The first step, ideally, is to install a fan. Not unlike the one you have in your bathroom. Install this on an outer wall or a ducted system.

A forced air fan will ensure the air from the surgery is removed from the room and exhausted externally. Contributing to your ACH.

Fans have different ratings and have different noise levels. Quieter is better in the surgery of course, so there will be no temptation to turn it down or off.

You can see that potentially there is no need to spend a fortune on a ventilation system to reduce fallow times.

It is also important to note that if you are sending air out but not bringing air into the room, you are creating a negative pressure.

Basically, the air pressure inside the room is lower than the air pressure outside the room. This means that when the surgery door is opened, potentially contaminated air is restricted from leaving the controlled zone and entering communal areas.

Investing now for the long term

Another possibility for improving air changes is via air purification.

As above, if you invest an independently verified machine conforming to EN1822, then you can avoid having to reduce the ACH by 50%.

Of course, it is great to reduce the fallow time and increase the number of treatments in your surgery. However, I truly believe that we also have an opportunity to reassure your team and, in turn, your patients.

This whole unfortunate episode has been such a major event in everyone’s lives. Even after a vaccine, the population will be more concerned about health and better informed moving forwards.

The added bonus of quality air purification compared to a ventilation fan alone is that it is great for all sorts of health reasons over the long-term. For example helping to avoid the spread of colds, flu, pollen and pet dander, as well as removing odours.

So your investment now is for the long term, not just the pandemic period.

Fit for purpose

Adding on a capture vacuum arm to your system, ie bringing a controlled collection point close above the patient’s mouth, will prevent a huge proportion of aerosol from even entering the surgery atmosphere.

Airborne contaminants are forced through the medical-grade HEPA filtration, exiting purified at the other end.

With this and some other options you are not changing your fallow time on paper. But common sense suggests it can only do good. It offers staff members and patients added security in these very difficult times.

Remember, only days ago (at the time of writing) air purification did not impact fallow times.

No one is going back to how things were a year ago. The only way to succeed is to plan for a better future.

As part of that, as stated succinctly by the FGDP(UK) and CGDent: ‘The type, design and manufacture of recirculating air cleaners is highly important. Not all models are equally effective. Take care in selecting the appropriate machine. Practitioners have a responsibility to ensure that it is fit for purpose and regularly maintained.’

Here to help

To ensure your team and patients remain safe in the pursuit of best practice and reduced fallow times, why not talk to one of our experts about your options?

For example, at Hague Dental, we believe that both the Cattani Aspi Aero 25 and IQAir Cleanroom series of air purifiers are ideal in the fight against COVID-19.

As authorised suppliers, we can supply, provide installation, validate with a calibrated air quality meter and offer ongoing support with annual maintenance for years.


For further information, please email [email protected] or call Hague Dental on 0800 298 5003.

Become a Dentistry Online member

Become a member