Returning to the workplace: ventilation advice

The risk of COVID-19 transmission can arise from droplet transmission, contact transmission and from aerosol transmission. Good ventilation plays a part in reducing how much virus is in the air, thus reducing the risk from aerosol transmission.  

21 January 2022

Due to emergence of the Omicrom variant, the new year brought with it some now familiar guidance: the government asked workers to avoid the office and to work from home where possible. In anticipation of returning to the office in early 2022, the Health and Safety Executive (the HSE) and the Scottish Government have issued guidance emphasising the importance of good ventilation and the role that plays,alongside other measures, in helping to reduce the spread of COVID-19. Please see the HSE guidance and the Scottish Government guidance for more details. 


What is meant by ventilation in the workplace?

It is a legal obligation that employers ensure there is an adequate supply of fresh air (ventilation) in enclosed areas of the workplace.   
This can be achieved by:

  • natural ventilation - fresh air coming into a building or room through open windows, doors, and vents; or
  • mechanical ventilation – fresh air being brought into a building or room from outside by fans and ducts

Why is good ventilation in the workplace important?

The risk of COVID-19 transmission can arise from droplet transmission (when people are in close contact with a person with the virus), contact transmission (when people touch surfaces with the virus) and from aerosol transmission (when people breathe in small particles in the air after a person infected with the virus has been in that same area). 
Good ventilation plays a part in reducing how much virus is in the air, thus reducing the risk from aerosol transmission.  

Assessing the risk of transmission 

The first step to identifying the level of ventilation required throughout the workplace is to carry out a risk assessment. 
There will be no one-size-fits-all. Within one workplace, different areas may have different ventilation requirements. The priority for your risk assessment should be identifying areas that are usually occupied and poorly ventilated.
A useful starting point could be tolist various workplace areas and describe how well ventilated they are. The HSE guidance poses a number of helpful questions:

  • How many people use or occupy the area? (The more people, the greater the risk).
  • How large is the area? (The larger the area, the lower the risk).
  • What tasks or activities take place in the area? (Physical exertion increases the risk).
  • Are there any features in the workplace that affect ventilation? (For example, large machinery).
  • Is there a complex ventilation system? (Typically in old buildings, buildings with several floors etc).

Practical points on workplace ventilation

There are some simple ways to address the issue of ventilation in the workplace:

  • Look for areas where people work and where there are no open windows, doors, or vents and no mechanical ventilation.
  • Fully or partly open windows and doors (but do not prop fire doors open).
  • Identify areas that feel stuffy or smell bad. 
  • Use carbon dioxide (CO2) monitors (higher levels of CO2 are an indication of poor ventilation).
  • Air rooms as frequently as possible, ideally when the room is unoccupied.
  • Consult with your employees.
  • Maximise the flow of fresh air and avoid recirculating air.
  • Ensure that the overall temperature remains comfortable for employees.

Further information

Ventilation in the workplace is becoming more and more of a priority in response to the COVID-19 pandemic (in addition to all of the other sensible measures that should be adopted to help reduce the risk of transmission). The Scottish Government recently made available an extra £5 million for ventilation in Scottish schools.  That is in addition to a previous announcement that local authorities would receive £10 million to invest in CO2 monitors. To ensure compliance with Scottish Government and HSE guidance and to minimise the risk of transmission, address any ventilation issues in your workplace today.

For further information, please contact Kevin Clancy, at, or your usual Shepherd and Wedderburn contact.