In this animated video the voice-over is supported with visualisations of the spoken text.

VOICE-OVER: "Good ventilation is necessary for a healthy and pleasant indoor climate.
It helps to prevent transmission of respiratory infections, such as COVID-19.
Ventilation means bringing in fresh air 24 hours a day.
Outside air ventilation constantly refreshes indoor air, removing pollutants, dust and moisture build-up.
But how can you achieve that?
You can ventilate an indoor space by opening windows, ventilation grilles or gaps, or by using mechanical ventilation systems.
In addition, it is important to air out rooms regularly.
You can air out an indoor space by opening windows and doors as far as possible for 10 to 15 minutes, letting lots of fresh air into the room –
such as after cooking, showering or hosting a group of people.
Would you like to know more? rivm.nl/en/coronavirus-covid-19/ventilation"