About the safety of UV disinfection of surfaces, air and human skin

UVB and UVC radiation reliably kills viruses and microorganisms – but the same radiation also damages skin and eyes. At the workplace, exposure time and dose are regulated; for private users and public facilities clear limits are missing, so the German Product Safety Act (ProdSG) together with Regulation (EU) 2023/988 applies. The safe options are therefore above all closed chambers and applications in the absence of people.

It has been proven that viruses and microorganisms can be killed efficiently and reliably with UVB and UVC radiation.

The use of UV lamps and UV LEDs in the fields of

• Sterilization in closed chambers
• Disinfection of surfaces with automated solutions
• UV surface disinfection in the absence of people
• mobile UVC lamps / UV-LED hand lamps
• Air cleaning with UV disinfection

While the maximum duration and dose of exposure is regulated in the workplace, there are currently no clearly defined exposure limits for private users and in public institutions. Several directives specify requirements in the EU. The Regulation (EU) 2023/988 on General Product Safety ensures that products available in the EU market are safe.

A product is considered safe if it complies with certain national regulations or EU standards. If no such regulations or standards exist, the safety assessment is based on:

• Commission guidelines;
• best practices in the affected field;
• current state of knowledge and technology;
• Safety levels that consumers can expect.

The use of closed chambers and automated solutions, e.g. for the disinfection of corona viruses, is comparatively safe and simple. For example, irradiation chambers usually offer complete protection by their closed design. Automated solutions for the disinfection of surfaces should be carried out in the absence of persons, since surface disinfection is generally not safe and exceeds the workplace limits. Here the question of access or control of human presence is often in the foreground. Exposure must be checked and determined for the case of failure, for installation and maintenance.

The use of mobile UVC lamps and UV LED systems for the disinfection of everyday objects, such as cell phones, is generally a problem. Here, due to the free propagation of the radiation, a safe application can be achieved only by safety instructions, training, correct use and, if necessary, safety equipment. Manufacturers and distributors must know the emission of the products and provide information on emission, classification, risk group, warning symbols and hazards.

With regard to UV air purification, also known as UV air disinfection, the following must be determined. The safety requirements for air cleaning devices are given in DIN EN 60335-2-65:2023-08; VDE 0700-65:2023-08 "Safety of electrical appliances for household and similar purposes - Part 2-65: Particular requirements for air cleaning devices". It superseded the earlier 2013-02 edition, which did not yet include any requirements for UV emission. The question of which residual emission is permissible therefore remains.

For the workplace this could be estimated on the basis of daily exposure. For example, the ACGIH exposure limit value for 253.7 nm is 6 mJ/cm² for a period of 8 h. This corresponds to an 8-hour continuous exposure at 2 mW/m² (0.2 μW/cm²).

For public institutions, private users, untrained persons or even children, neither exposure duration nor exposure limit values are specified. Therefore a simple estimation is not possible.

Special requirements for air cleaning devices with UVC emitters are named in amendment A2 to the 2013-02 edition (DIN EN 60335-2-65/A2:2014-04; VDE 0700-65/A2:2014-04); the edition in force today is DIN EN 60335-2-65:2023-08; VDE 0700-65:2023-08. For example, a residual emission of less than 3 mW/m² = 0.3 µW/cm² must be observed. Simplified, no UV must be emitted. A calibrated radiometer with a resolution and detection limit, at least by a factor of 10 better, is sufficient for the assessment.

We are pleased to be available as an independent partner for measurement, consulting, calibration and testing. Please ask us.

Finally, a note on the so-called Far UV disinfection with 222 nm:

UV irradiation of skin for disinfection is generally not recommended. The Federal Office for Radiation Protection in Germany (BfS) advises against exposing of human skin to intensive UV radiation to get rid of the corona virus. Caution is required when using UVC radiation. There is a risk of damage to the eyes and skin. The BfS also advises caution with devices that work with "Far-UV-C" sources. Of course, the requirements of occupational safety must be observed for these "Far-UV-C" wavelengths as well.

The following literature is intended to help in dealing with the issues surrounding UV disinfection:

CIE 155 "Air disinfection by ultraviolet radiation", 2003

CIE Position Statement on the Use of Ultraviolet (UV) Radiation to Manage the Risk of COVID-19 Transmission, May 2020

DIN EN 62471:2009-03 Photobiological safety of lamps and lamp systems; for UV lamp products additionally IEC 62471-6:2022 – Part 6: Ultraviolet lamp products

EN 14255-1:2005 Measurement and assessment of personal exposures to incoherent optical radiation - Part 1: Ultraviolet radiation emitted by artificial sources in the workplace

EN 14255-4:2006 - Measurement and assessment of personal exposures to incoherent optical radiation - Part 4: Terminology and quantities used in UV-, visible and IR-exposure measurements

ISO 15858:2016 UV-C Devices — Safety information — Permissible human exposure

ISO 15714:2019 Method of evaluating the UV dose to airborne microorganisms transiting in-duct ultraviolet germicidal irradiation devices

DIN EN 60335-2-65:2023-08; VDE 0700-65:2023-08  Household and similar electrical appliances - Safety - Part 2-65: Particular requirements for air cleaning appliances (supersedes the 2013-02 edition and its amendment A2:2014-04)

DIN EN IEC 60598-1:2022-03: Luminaires - Part 1: General requirements and tests (the EN 60598 series may be used as the basis for risk assessment considering mechanical, electrical and thermal safety)

Directive 2006/25/EC (Artificial optical radiation)

Regulation (EU) 2023/988 on general product safety (replaces Directive 2001/95/EC. The new regulation has been in effect since December 13, 2024.) In Germany, the common abbreviation is the Product Safety Act (ProdSG).

ICNIRP Guidelines on Limits of Exposure to Ultraviolet Radiation of Wavelength between 180 nm and 400 nm (Incoherent Optical Radiation) published in Health Physics 87(2): 171-186, 2004

GLA "Position Statement on Germicidal UV-C Irradiation UV-C SAFETY GUIDELINES" Stand 05-2020

GLA "Germicidal UV-C Irradiation -SOURCES, PRODUCTS AND APPLICATIONS" booth 09-2020

Stand 12-2020

Note:

These lists of limit values, protective measures and requirements are not complete. The laws, guidelines and standards apply, in the respectively valid version with the respectively valid parts.  It is our opinion. All information without guarantee and claim to completeness

How the effect itself comes about – fluence, dose-response curves and reactor technologies – is covered on the market page UV disinfection; the application to packaging materials and filling lines is described under packaging and filling technology.