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Into the Future with Metrology - The Challenges of Medical Technology

Fighting viruses in indoor air

DIN publication on the use of UV-C air purifiers, in particular in daycare centers and schools

PTB-News 2.2022
Especially interesting for

manufacturers, planners and testers of UV-C air purifiers

Aerosols with coronaviruses in a classroom (symbolic picture: Adobe Stock/Alexander Limbach)

Coronaviruses are mainly passed on via aerosols, which makes them particularly dangerous in enclosed spaces. As studies have shown, UV-C air purifiers are able to reliably eliminate coronaviruses. If the air passing through the device is irradiated with a dose of approx. 70 J/m2 of UV-C, it is possible to inactivate roughly 99 % of all airborne bacteria and viruses. Manufacturers and users of UV-C air purifiers therefore need to make sure that a sufficient dose of UV-C is delivered during a single passage.

The DIN/TS 67506 technical specification titled “Disinfection of room air with UV radiation – UV-C secondary air units” applies to devices featuring closed operation and active ventilation. It contains numerous technical details and method descriptions. Besides providing information on the effectiveness of devices, these details also address their efficiency in rooms of different sizes. The socalled hygienic air delivery rate (HADR) indicates how many cubic meters of disinfected air the device is able to produce hourly. In this way, it is possible to calculate the number of air renewals that are theoretically attainable to effectively reduce airborne germs for each room size and for each device.

An especially important aspect is that of safety, in particular protection from UV radiation. Devices must not cause harm to persons who remain in the immediate vicinity of a device for a longer period of time. A small amount of UV-C radiation may be emitted even by enclosed UV radiation sources. To minimize this amount, these devices should be designed such that they qualify for the Exempt risk group under EN 62471 “Photobiological safety of lamps and lamp systems”: The limit values stated in this standard refer to healthy adults and are specified on the basis of EU Directive 2006/25/EC such as to essentially rule out any hazard to people when devices are used as intended.

When operated near vulnerable persons, such as children or persons with existing eye or skin conditions, devices must emit no measurable UV radiation within the accessible area. According to the state of the art in metrology, this is the case if the UV irradiance in the spectral range from 200 nm to 300 nm at a distance of 20 cm from the device and up to a height of 180 cm from the ground does not exceed 200 μW/m2 anywhere. This is also laid down very clearly in the technical specification.


When designed, tested and used according to the recommendations of DIN/ TS 67506, UV-C air purifiers can contribute to fighting the pandemic. The next step will consist in developing a corresponding DIN standard based on this technical specification.


Peter Sperfeld
Department 4.1
Photometry and Spectroradiometry
Phone: +49 531 592-4144
Opens local program for sending emailpeter.sperfeld(at)ptb.de

The technical specification

DIN/TS 67506: Disinfection of room air with UV radiation – UV-C secondary air units. Beuth-Verlag, Opens external link in new windowwww.beuth.de