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How a ventilation upgrade saved my practice

Blog Author Cliff Palmer

Blog Date 26/10/2020

Cliff Palmer, a practice owner in Yorkshire, discusses how he upgraded the ventilation in his practice and the impact that it has had on their capacity.


The team at Cliff Palmers dental practice - photo taken in 2019.jpg

The team at Cliff Palmers dental practice (photo taken in 2019)


Back in May, I read something on the government’s website that sparked the idea of how my practice could survive the COVID-19 pandemic.


This earlier guidance from Public Health England discussed the transmission characteristics of viruses and the level of risk in a surgery following an aerosol-generating procedure (AGP). Mitigation against this risk depended on ventilation and air changes within the room. It said that, on average, surgeries achieve six air change per hour (ACH) which means it can take 60 minutes to clear infectious particles from the air. However, if a surgery could achieve 10 -12 ACH then it would be considered safe within 20 minutes. But how difficult would that be?


I contacted John Taylor, who had installed my air conditioning, to discuss how I could increase the air changes in my surgery. I was surprised to learn that he had spent a large part of his 25 year career installing ventilation units in hospital treatment rooms and was well versed in the infection prevention control guidance. He outlined my options and I decided to push ahead. Installation work began three weeks after we were allowed to return to face-to-face care in June.


Our fallow time is now down to 20 minutes and we are seeing four times as many patients than we were after lockdown. The recommendations from the recent SDCEP report, published in September, followed by the new standard operating proceduresthis week reassure us that this was the right approach to take.


Here is how we did it.


Achieving 10 air changes per hour

“The outgoing and incoming airflow ... don’t make contact so there is no contamination.”

We installed three mechanical ventilation heat recovery units, or MVH, into my practice - one in each surgery. The specific units installed were Mitsubishi Lossnay. These machines bring clean air in and take the stale air out through a duct and weather louvre in the wall. The outgoing and incoming airflow passes by each other but don’t make contact so there is no contamination. There is, however, energy transfer, which means the air coming in is almost the same temperature as the air travelling out. That’s important as the winters are cold in Yorkshire.


The machines pass all incoming air through a filter that collects pollutant particles, dust and bugs. On the top settings, they guarantee 10 ACH. That means that 400 cubic metres of clean air is being pumped into my surgery every day. Thus a patient that arrives for an AGP at 10am is breathing entirely different air to a patient that came an hour earlier.


Logistics and aesthetics

My practice is a 1960s purpose-built property. I was lucky because my two larger surgeries have a loft that was a perfect space to house the new ventilation units. The only visible evidence of the machine is a device on the wall to control the airflow. There is also an extract grill and single supply diffuser which have been neatly fitted into my suspended ceiling.


Dental surgeries located in residential properties from the Victorian era may not find the installation quite as straightforward. These cases might have more in common with my third and smaller surgery which does not have a loft. Here, the unit had to be mounted against the ceiling above the window and two small holes were diamond cut through the wall to the outside (where John had fixed two louvre vents). Internally, it wasn’t aesthetically pleasing so we arranged for a joiner to build a cabinet over it so that it was in keeping with our décor.


Extract duct and single diffuser fitted into one of the suspended ceiling tiles. Extract duct and single diffuser fitted into one of the suspended ceiling tiles. There is another identical grille on the other side of the room.

Weather louvres on the outside of one of Dr Palmer's surgeries.

Weather louvres on the outside of one of Dr Palmer's surgeries.

The Mitsubishi Lossnay "mechanical ventilation heat recovery" unit

The Mitsubishi Lossnay "mechanical ventilation heat recovery" unit installed inside the loft above one of Dr Palmer's larger surgeries.


Installation and running costs

“The starting price for the smaller unit is around £2.5k plus VAT.”

The cost of the units is based on the size of your surgery (usually around 30 cubic metres squares to 60 cubic metres squared). The starting price for the smaller unit is around £2.5k plus VAT, while the larger units are around £3k. For a three room practice, you’re probably looking at around £10k. You need to factor in other things, such as carpentry/ engineering work, in case you don’t have available lofts or louvres. An annual inspection to check the filters is an additional cost to consider.


I made use of the business recovery loan to purchase three of the larger machines. In hindsight, the smaller surgery could have been served with the smaller and cheaper unit. In the small room, the larger unit - on the highest setting - achieves an incredible but unnecessary 35 ACH. So I keep it on the second setting - 15.2 ACH - and save on electricity. Running all three machines all day long has increased my monthly energy bills by £60.



I was warned that installing these units would be potentially disruptive, as engineers would be inside the building to carry out the work. But we managed to minimise this disruption. We did the work in early July which was relatively quiet and also managed to do some of it on weekends. It took a total of six days. Having the extra surgeries was a huge help in allowing us to shuffle things around when necessary. I’m relieved to have got the work done early, because following the SDCEP report and the new guidance, I am sure that there will be increasing demand for ventilation work.


Noise pollution

Like much modern technology, these units run very quietly. I almost want the machines to be a bit louder so that patients can hear them when I describe our ventilation improvements. I have to tell them that if they listen very carefully that they might catch the humming.

“I would actually be more bothered by an open window than any noise that these units make.”


I would actually be more bothered by an open window than any noise that these units make. When you are wearing fitted PPE, clear communication can already be a bit of a struggle. So if you are also trying to deliver serious information that a patient doesn’t want to hear and then, for example, a car beeps at a cyclist outside the window, having the window open can make for a far more stressful situation.


Popular online alternatives

I read about other ‘virus killer’ solutions online before I contacted John, but few seemed to offer workable alternatives. Some use ultraviolet to zap the virus which was not discussed in any of our guidance so I didn’t feel comfortable pursuing it. Others work as a mechanical extract but don’t control the new supply of air which can increasing the risk of contamination.
Air purifiers also did not seem like the right answer to me, as they do not move air around. That means, they only clean the air surrounding it and not the entire room. None of these options could achieve 10 air changes per hour as per the guidance.


Beyond ventilation

The ability to fit an unplanned AGP in without the lengthy fallow time logistically revolutionised our post lockdown practice. Admittedly, it isn’t all plain sailing but it is significantly easier since the mitigation.


We are now fully operational and running at the highest capacity we can hope for in these circumstances.


However, I still worry about the mingling areas and having too many people in the practice. We are constantly working to keep the practice hygienic and safe. It’s an ongoing process and there is a lot to consider beyond the ventilation issue.


Dr Cliff Palmer

Cliff Palmer

Practice owner, Finkle Hill Dental Care, Leeds