Good ventilation is not only required for a healthy and pleasant indoor climate, but it also helps to limit the transmission of respiratory infections, such as COVID-19. Ventilation means refreshing the indoor air with fresh air from outside, 24 hours a day. This ensures that the fresh outdoor air constantly replaces some of the air indoors which is contaminated with fine particles, water vapour, etc.

You can ventilate an indoor area by leaving windows open at a tilt, by opening ventilation grilles or gaps, or by using mechanical ventilation systems. In addition, it is important to air out indoor spaces from time to time. This means, for example, leaving doors/windows opposite each other wide open for 10 to 15 minutes to create a good draft. By doing so, you are refreshing most of the air in your indoor space all at once. This is something to do after cooking, showering, or hosting multiple people, for example.

Air out the room to achieve good indoor humidity

A good balance of indoor humidity can help reduce the risk of spreading COVID-19. Especially on (very) cold days in winter, the air inside your house can get very dry. Try to keep the humidity between 40-60% (if necessary, this can be measured with a humidity meter; some thermostats can also measure it). Many plants in your home can help you achieve good indoor humidity. If the air gets very dry, you can let the laundry dry in the room. In other seasons of the year, or in buildings where it is often too humid inside, this is usually not necessary. There are still many questions about the role of low humidity in the spread of the coronavirus SARS-CoV-2. The recommendation to achieve a good balance in indoor humidity is given as a precaution. However, there is no reason to leave the room or to call the Municipal Public Health Services (GGDs) or the municipality if it is temporarily very dry in the house.

Cooling

When the weather is warm, you might use a fan or air conditioner to cool your home. Keep in mind that these devices do not refresh the air, but only move it around. If you have guests in your home, make sure that your devices are not creating an air flow from one person to another. See also the National Heat Plan.

Air purifiers and COVID-19

Air purifiers can reduce any viruses or bacteria present in the air flowing through the device. They achieve this by blocking viruses and bacteria (for example using filters) and/or killing them (using such methods as UV-C, ionisers, or ozone). A separate electrical device that can be placed in a room is called a standalone or portable air purifier. 

There is no scientific evidence that this type of air purifier prevents or reduces transmission of the coronavirus SARS-CoV-2 in public places or at home. It is unlikely that an air purifier situated in a different part of the room will affect transmission of the virus between two people who are less than 1.5 metres apart. This also applies to transmission via hands and surfaces.

Air purifiers are not an alternative for indoor spaces or public spaces where there is insufficient ventilation. In any case, the space should comply with the applicable regulations for ventilation to create a pleasant and healthy indoor climate. Similarly, air purifiers are not a suitable replacement for the COVID-19 measures, such as staying home if you have symptoms, distancing, avoiding crowds, working from home as much as possible and practising good (hand) hygiene. These measures are aimed at preventing all forms of transmission. The implementation of these measures prevents infection with the coronavirus SARS-CoV-2. RIVMNational Institute for Public Health and the Environment does not play any role in approving or advising a particular type of air purifier. 

Questions about ventilation

What are RIVMNational Institute for Public Health and the Environment ’s recommendations about ventilation?

At a minimum, RIVM recommends compliance with the Dutch Buildings Decree (Bouwbesluit) and all current recommendations and guidelines. There are no indications that additional measures are necessary. For the full list of recommendations, see the LCI website (in Dutch).

Can ventilation prevent the spread of COVID-19?

Good ventilation is important for a healthy indoor climate. Ventilation also helps to limit the transmission of respiratory infections, such as COVID-19. However, the degree to which ventilation (refreshing the air) specifically inhibits the transmission of COVID-19 is unknown. This is why it remains important to, in addition to ensuring proper ventilation, also observe all the general recommendations, such as washing hands often, staying home if you have symptoms, getting tested, and maintaining distance from others.

Are there special recommendations for ventilation in nursing homes, cafés and restaurants, sports clubs and schools?

The Dutch Government provides information about ventilation of buildings. RIVM also has general information available about hygiene, ventilation and indoor environments. Additional recommendations are available specifically for schools and care homes.

Can air recirculators be used safely?

It is important to provide adequate ventilation: ensuring that indoor air is sufficiently refreshed with fresh air from outside. Spaces that use recirculation systems that introduce minimal amounts of fresh air, or no fresh air, are not in compliance with the Buildings Decree. For precautionary reasons, use of these types of recirculation systems is not recommended unless they introduce an adequate amount of fresh air throughout the day. Some recirculation systems do have the capacity to introduce fresh air. When using these systems, make sure they are configured to add enough fresh air into the space to guarantee good ventilation.

Can I use air conditioning? 

Yes, you can use ventilation systems and air conditioners for cooling your home

Whether or not the use of a mobile air conditioning unit in shared spaces presents a greater risk of infection is not yet clear. To avoid unnecessary risk, we therefore recommend only using mobile air conditioning units in shared spaces if there is no other option for cooling. If you do this, make sure that you do not create an air flow from one person to another.

Can I use a fan? 

Yes, for personal use in your home/within the family environment, you can use a fan to create a cooling airflow. To increase the cooling effect, you can place a frozen water bottle in front of the fan. 

Whether or not the use of a fan in shared spaces presents a greater risk of infection is not yet clear. To avoid unnecessary risk, we therefore recommend only using fans in shared spaces if there is no other option for cooling. If you do this, make sure that you do not create an air flow from one person to another.

For more information, see the page on Heat and COVID-19 (Dutch only).