Ventilation is the process of introducing fresh air into indoor spaces while removing stale air. Letting fresh air into indoor spaces can help remove air that contains virus particles and prevent the spread of coronavirus (COVID-19). When someone with COVID-19 breathes, speaks, coughs or sneezes, they release particles (droplets and aerosols) containing the virus that causes COVID-19. While larger droplets fall quickly to the ground, smaller droplets and aerosols containing the virus can remain suspended in the air. If someone breathes in virus particles that are suspended in the air, they can become infected with COVID-19. This is known as airborne transmission.
In poorly ventilated rooms the amount of virus in the air can build up, increasing the risk of spreading COVID-19, especially if there are lots of infected people in the room. The virus can also remain in the air after an infected person has left. Bringing fresh air into a room and removing older stale air that contains virus particles reduces the chance of spreading COVID-19. The fresher air that is brought inside, the quicker any airborne virus will be removed from the room.
Ventilation is most important if someone in your household has COVID-19 or if you are indoors with people you do not live with. Good ventilation has also been linked to health benefits such as better sleep and fewer sick days off from work.
Bear in mind that ventilation does not prevent COVID-19 from spreading through close contact and is only one of the actions you should take to reduce the spread of COVID-19. This is why it is important that everybody follows the guidance on how to stop the spread of COVID-19 all of the time, especially as it is possible to have COVID-19 with no symptoms. You can pass COVID-19 on to others if you are only symptomatic or asymptomatic.
Reduce the amount of time you spend indoors with people you do not live with
If COVID-19 is spreading in your community, stay safe by taking some simple precautions, such as physical distancing, wearing a mask, keeping rooms well ventilated, avoiding crowds, cleaning your hands, and coughing into a bent elbow or tissue.
Make sure you understand and abide by the current rules and restrictions on meeting others.
Besides, you should minimise the amount of time you spend indoors with people you do not live with or share a support bubble with. Avoid meeting people in spaces with a limited flow of fresh air such as rooms without ventilation or windows that are never opened. The risk is greater in small rooms as the concentration of virus in the air can build up more quickly than in larger areas.
Ventilation in the workplace and non-domestic settings
Ventilation should be considered as part of making your workplace or indoor public space COVID-secure. It is important to identify and deal with areas that are not well ventilated. The more people occupying an area that is poorly ventilated, and the longer they remain in it, the greater the risk of spread of COVID-19.
Control measures such as avoiding certain activities or gatherings, restricting or reducing the duration of activities, providing ventilation breaks during or between room usage should be considered alongside ventilation for reducing the risk of airborne transmission.
Any actions to improve ventilation should not compromise other aspects of safety and security (for example, avoid propping open fire doors), and should consider other consequences such as health and wellbeing impacts from thermal discomfort.
Employers should provide employees with clear guidance on ventilation, why it is important, and instruction on how to achieve and maintain good natural ventilation or to operate systems if there are user controls.
Make sure mechanical ventilation systems are maintained in line with manufacturers’ instructions. Set ventilation systems to using a fresh air supply and not recirculating indoor air, where possible. Assessing the requirement and performance of ventilation systems in many environments requires engineering expertise. In addition, ventilation design may be specific to the setting. For some existing and older buildings, ventilation systems may not have been designed to meet current standards and additional mitigations may be needed. If you are unsure, seek the advice of your heating, ventilation and air conditioning (HVAC) engineer or adviser.