Blue light hazard | ERCO Lighting knowledge

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Photobiological safety and blue light hazard

Wavelengths from 400nm to 500nm are particularly high-energy and can cause damage to the retina of the human eye. Because this spectral range corresponds to that of blue light, it is also termed blue light hazard. In addition to the wavelength of the light, the intensity of the light source, i.e. the light intensity, and the duration of exposure to the retina, also play an important role in blue light hazard.

What is photobiological safety with LED luminaires?

According to the Product Safety Act, all products, in every respect, have to be safe. Photobiological safety considers risks due to emitted radiation in the visible range (light) and the adjacent UV and IR spectral ranges, whereby LEDs for lighting purposes emit radiation almost exclusively in the visible range.

When wavelengths between 400nm and 500nm are exposed to the retina with high intensity for a certain time, irreversible damage to the retina can occur due to photochemical processes. To ensure that this does not occur, the EN 62471:2008 standard defines the relevant measurement procedures and divides the hazard potential into four risk groups (RG) to which a luminaire is assigned. The risk groups define how the specific luminaire can be safely used and which safety distances must be observed where applicable.

These are the four risk groups (RG):

RG0 and 1 are considered non-hazardous and do not require any special measures.

In the case of RG2 LED luminaires, a specified distance between the viewing eye and the luminaire must not be fallen below for more than 100 seconds.

In the case of luminaires with RG3, even a brief look into the light source is enough to trigger damage. Luminaires with risk group 3 are generally not permissible. The sun in a clear sky would be classified as risk group 3.

What does RG2 mean with LED luminaires?

The degree of risk is indicated in so-called risk groups (RG). The classification of an LED luminaire into the risk groups results from the factor emitted radiation evaluation and intensity. The measurement and the classification of the luminaire result in measures that are prerequisites for safe operation of the luminaire.

From risk group 2 (RG2), luminaires and lamps must be labelled with a warning. In order to use the luminaire safely, a minimum distance between the eye and the luminaire must be specified in addition to the RG2 information on the luminaire. Complying with the distance ensures that even prolonged staring into the luminaire does not cause any damage. It is possible that classifying a product as RG2 may result in corresponding restrictions of use. According to current standards, luminaires with narrow light distribution, high wattage and cool light colour are often classified as RG2.

Interesting:
Usually a person reacts "automatically" to excessively strong, dangerous radiation by instinctively closing the eyes and/or turning away the head. However, in children, the sick and the elderly, this reflex may not yet function or no longer function. If these groups of people can come into the vicinity of a luminaire with RG2, for example in kindergartens, hospitals and care homes, it must be ensured that the minimum viewing distance is maintained.