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WHO recommends clean indoor air to prevent the spread of COVID-19

In view of COVID-19, the World Health Organization (WHO) has issued advice to improve indoor air. The risk of becoming infected is greater in crowded and inadequately ventilated areas where infected people spend long periods together. By taking measures in the field of ventilation, supplemented with air cleaning, the quality of the air is improved and the risk of the virus spreading is reduced.

What is known about the transmission and spread of the virus?
Knowledge about the transmission of the SARS-CoV-2 virus is constantly evolving. The transmissibility of the virus depends on the amount of viable virus emitted by a person, the type of contact with others, the environment and what other measures have been taken. The virus can spread through the mouth or nose of an infected person in small liquid particles when the person coughs, sneezes, sings, breathes heavily or talks. The particles have different sizes, ranging from larger respiratory droplets to smaller aerosols.

The risk of crowded, poorly ventilated areas
Aerosol transmission can take place in crowded and inadequately ventilated areas, where infected persons spend long periods of time. It is therefore important to ensure sufficient clean air and compliance with (hygiene) measures to reduce the risk of COVID-19 infection.

How do you create clean indoor air?
Clean air is introduced into a room through ventilation. The overall purpose is to ensure that the air is healthy to breathe. Building ventilation has three basic elements: ventilation speed, air flow direction and air distribution. In this last part, it is important that air pollutants, which are generated in every part of the room, are removed in an effective and efficient way.

The role of air purification in generating sufficient clean air
There are three methods that can be used to ventilate a building: natural (open window), mechanical (ventilation system), and hybrid (mixed mode) ventilation. Depending on the space, it is recommended to use a certain ventilation rate; this means how many times per hour the total air in a room has to be refreshed. If the ventilation options are not sufficient to generate this required amount of clean air, it is recommended to use mobile air cleaners to compensate for this so-called ventilation shortage.

The danger of polluted outdoor air
Outdoor air pollution is a major problem affecting all countries. This pollution causes an estimated 4 million premature deaths worldwide each year in both urban and rural areas. Without the correct measures, the polluted outside air is brought in through a ventilation system or open window. Air cleaners can be used in such situations to filter harmful particles from the indoor air.

WHO roadmap to create clean indoor air
Based on extensive research, WHO has drawn up a roadmap to improve the indoor air in buildings. For more information about the steps to be taken, please refer to the report, which can be downloaded via the image at the bottom of this message.

Are you looking for help whilst creating a healthy working environment? We have been specialized in cleaning various types of indoor air pollution for over 45 years. Naturally, our advisers will be happy to inform you about the possibilities for your specific situation. You can contact us at

Click on the image to download the report

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