Mobile air purifiers are booming in times of pandemics. Manufacturers of these devices outbid each other with superlatives. The German statutory accident insurance (DGUV) sees the use of the air recirculation units in a much more differentiated way. For example, the accident insurer points out important boundary conditions that must be observed when using the devices in classrooms.
The German workplace regulation A3.6 provides important information on the supply of fresh air
The be-all and end-all of any defence against infection in closed rooms is a sufficient supply of fresh air in addition to distance control and face masks. The workplace regulation A3.6 provides important information on correct ventilation. The CO2 concentration of 1,000 ppm should not be exceeded in rooms. For rooms with free ventilation, this means regular shock ventilation via open windows. In meeting rooms, ventilation should be started after 20 minutes for 5 minutes in autumn and 3 minutes in winter. The carbon dioxide concentration can be easily monitored with CO2 traffic lights.
Mobile devices can only be used selectively
Mobile room air cleaners can be useful as a supplement, if the dimensioning and positioning in the room are considered. The DGUV points out that air cleaners can only be used selectively. This disadvantage must be compensated by higher air volume flows, clever installation in the room or the use of several devices distributed in the room. The air flow in the room is influenced by fixtures, furnishings or by angled room situations. People as heat sources or electrical devices and light sources in the room can also deflect the air flow.
Evaluate the system as a whole
The filter performance should be tested according to DIN EN 1822. The DGUV recommends that operators of room air cleaners do not rely solely on manufacturer’s specifications. Also, the system as a whole should be tested and not only the filter performance. This is not always apparent from the manufacturer’s specifications. An important aspect is the tightness of the filter. If there is no tightness, some of the air drawn in will flow past the filter and the fit will only be partially effective. The accident insurer therefore recommends requesting the test protocols.
https://www.dguv.de/medien/inhalt/mediencenter/pm/pressearchiv/2020/4_quartal/fachbeitrag_raumluftreiniger.pdf (in German)
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