Ventilation and Air Conditioning during the Coronavirus (COVID-19) Pandemic


The HSE has reviewed this guidance, which states that employers must make sure there is an adequate supply of fresh air (ventilation) in enclosed areas of the workplace.

Maximising the fresh air in a space can be done by:

  • Natural ventilation which relies on passive air flow through windows, doors and air vents that can be fully or partially opened.

  • Mechanical ventilation using fans and ducts to bring in fresh air from outside.

  • A combination of natural and mechanical ventilation, for example where mechanical ventilation relies on natural ventilation to maximise fresh air.

The HSE has reviewed its guidance, which will apply in most workplaces, and aims to help employers and their workers to:

  • Assess the risk from aerosol transmission in enclosed areas.

  • Identify poorly ventilated areas.

  • Decide on the steps to take to improve ventilation.

Ventilation is important because adequate ventilation reduces how much virus is in the air. It helps reduce the risk from aerosol transmission, when someone breathes in small particles (aerosols) in the air after a person with the virus has been in the same enclosed area. The risk is greater in areas that are poorly ventilated.


Ventilation reduces the aerosol risk but has minimal impact on:

  • Droplet transmission (where people are within 2 metres of each other).

  • Contact transmission (touching surfaces).

The guidance acknowledges that adequate ventilation can look different in different workplaces or settings.


The risk of aerosol transmission can be reduced by:

  • Making sure infected workers (or any visitors with Coronavirus symptoms) do not come into the workplace.

  • Providing adequate ventilation with fresh air.

  • Limiting the number of people in an area.

  • Thinking about activities that increase deeper breathing (including singing, physical exertion and shouting).

  • Workers spending less time in occupied areas.

A risk assessment should consider what adequate ventilation looks like in a particular workplace.


The guidance is available in full here.


HSE June 2021

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