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Ventilation requirements for Scottish based Dental Practices

Information, Mechanical

Ventilation systems have always been an important part of an enclosed space, regardless of its use.  However with the Covid-19 pandemic, ventilation and the circulation of air in enclosed spaces has gone under the microscope. In June of 2021, the Scottish Government released details of a new policy on ventilation requirements in dental premises in the country.

What are the ventilation requirements?

Ventilation system used in dental practices will now have to meet the set requirements of 10 air changes per hour.

The transmission characteristics of viruses and the level of risk in a surgery following an aerosol-generating procedure (AGP) means that ventilation requirements in dental practices have had to be amended. It is estimated that currently, on average, most dental surgeries in Scotland achieve six air change per hour (ACH). This means that it can take up to 60 minutes to clear infectious particles from the air in an enclosed dental practice room. With the new legislation requesting a dental surgery achieve a minimum of 10 ACH, this will make the area safe within just 20 minutes.

dental practice ventilation legislation

Why is ventilation in a dental surgery so important?

The airborne transmission of viruses such as Covid-19 can make dental practices a dangerous working environment for both dentists and patients. It is important to protect both key workers and patients and reduce the amount of ‘spatter’ that can be emitted into the air during dental procedures.  To do this, sufficient ventilation systems must be in place to aid the removal of these airborne diseases.

The Air Changes per Hour (ACH) is the measurement that tracks how many times the air is changed per hour in a given space.  In a working environment such as a dental practice, it is important to make this space free from any viral or bacterial pathogens in as short a time as possible. Put simply, the more air changes per hour, the less risk to both dental teams and patients.

How can a dental practice make changes to the ACH?

There are three ways that a dental surgery can affect the ACH:


Reducing the number of pollutants, microbes and air borne viruses from being introduced to the air.


Having an effective ventilation system installed that allows enough clean, fresh air to enter a space and dilute the pollutants in the air.


Air purifying systems that can remove a number of pollutants from the air.

Effective ventilation is the primary focus for the new Government guidance and they are advising that external extractor fans are now required to keep spaces well ventilated and that the ventilation system is powerful enough to ensure a maximum fresh air flow rate. The Aerosol Generating Procedures (AGP) is dependent on the ventilation and rate of air change within a room.

The new Scottish Government guidelines state:

  • For a treatment room with more than 10 air changes per hour (ACH) and which can be evidenced to the NHS Board, a minimum of 20 minutes ‘fallow time’ (after which entrance to the room without PPE is allowed) before cleaning is recommended.
  • For a treatment room with external ventilation (natural or mechanical) with less than 10 ACH or with no data on number of air changes per hour available, the fallow time would be 60 minutes.
  • For a treatment room with no external ventilation (natural or mechanical), the absence of air changes means that AGPs should not be undertaken.

What is the Fallow Time?

Fallow time is the term that refers to the settlement period.  In dentistry, the number of procedures available means that a lot of airborne ‘spatter’ is produced. To reduce the number of infectious micro-organisms in a dental setting, the fallow time requires a set period of time to pass before the next dental patient is allowed inside the room for treatment. Ventilation systems can reduce the fallow time between patient appointments and reduce the infection rates, keeping dental teams and patients safe.

How HF Group can help

HF Group Mechanical Services team of engineers specialise in the design, supply, installation and commissioning of a huge range of ventilation systems for use in medical facilities.

Whether working with building contractors or directly with the customer, we can work on integrated or standalone ventilation systems.

To find out more about our work in ventilation systems, please click the link below:

Ventilation Installation Services

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