Good ventilation exchanges indoor air for outdoor air.
If someone is infected with a respiratory virus such as COVID-19, they can spread the virus when they breathe, talk, laugh, sing, cough or sneeze. Bringing fresh air into the room helps to prevent the build up of virus particles indoors.
One way you can improve ventilation is by opening windows or doors. The building’s mechanical ventilation, meaning central heating or ventilation and air conditioning (HVAC) system, also replaces the air with fresh air.