HSE’s guidance on ventilation and air conditioning during the coronavirus (COVID-19) pandemic

HSE have issued extensive guidance on vendilation and air conditioning during the COVID-19 pandemic.


The law says employers must make sure there’s an adequate supply of fresh air (ventilation) in enclosed areas of the workplace. This has not changed during the pandemic.

​You can do this by using:

  • natural ventilation – fresh air comes in through open windows, doors or air vents. This is also known as ‘passive airflow’, or mechanical ventilation – fans and ducts bring in fresh air from outside.

​Ventilation isn’t the only way of making sure you’re working safely. You should also make sure workers are keeping the workplace clean and washing their hands frequently. You can also identify other control measures by your risk assessment.​

This guidance will help you and your workers:

  • identify poorly ventilated areas
  • assess the risk from breathing in small particles of the virus (aerosol transmission) in enclosed areas
  • decide on the steps you can take to improve ventilation​

Why ventilation is important

Adequate ventilation reduces how much virus is in the air. It helps reduce the risk from aerosol transmission.​

Aerosol transmission can happen when someone breathes in small particles in the air (aerosols) after a person with the virus has been in the same enclosed area.​

The risk from aerosols is greater in areas that are poorly ventilated.​

Although ventilation reduces the risk from aerosols, it has minimal impact on:

  • droplet transmission (from people being in close contact)
  • contact transmission (touching surfaces)​

Your ventilation is likely to be adequate to minimise the risk of COVID-19 aerosol transmission if the rooms or spaces in your building(s) are:

used within the occupancy limits specified in the building design, and have a sufficient fresh air supply to meet the current minimum building standard. You can get advice from a competent ventilation engineer or, as a precautionary approach, operate your system on the maximum air flow rate

Assessing the risk of aerosol transmission

Adequate ventilation can look different depending on the workplace or setting.​

You can reduce the risk of aerosol transmission by:

  • making sure infected workers (or anyone with COVID-19 symptoms) do not come into the workplace
  • providing adequate ventilation with fresh air​

Deciding what adequate ventilation looks like in your workplace should be part of a risk assessment.​

When you have completed an assessment, there are examples of improving ventilation to reduce transmission.​

You should also make sure any control measures you identify by your risk assessment take account of the public health regulations and guidance for the nation you are working in.​

To view the advice in full, please click here.

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