Photobiological safety

Photobiological safety concerns the assessment of potential biological effects of optical radiation on the human body. In practical terms, it addresses whether a given light source—under typical conditions of use—may cause harm to the eyes or skin due to excessive light intensity, ultraviolet (UV) radiation, infrared (IR) radiation, or specific portions of the visible spectrum.

What Photobiological Safety Evaluates

The evaluation focuses on health risks associated with exposure to radiation from artificial light sources. The objective is to ensure that products are designed and used in a way that does not endanger human health.

Risk Groups According to IEC 62471

Photobiological safety assessment is defined by the international standard IEC 62471, which specifies measurement methodology and classifies light sources into four Risk Groups (RG0–RG3). These categories express the level of hazard based on defined exposure durations and normal conditions of use:

• RG0 (Exempt Group) – the source is considered safe with respect to photobiological effects under normal use.
• RG1 (Low Risk) – the risk is minimal; normal use is considered safe because natural aversion responses (e.g., blinking or looking away) limit exposure.
• RG2 (Moderate Risk) – may present a hazard if viewed directly for extended periods; requires appropriate use or exposure limitations.
• RG3 (High Risk) – may be hazardous even with short exposure; typically applies to high-intensity sources requiring strict access control and protective measures.

Assessed Factors and Types of Hazards

The standard evaluates the combined effect of radiation intensity and exposure duration across different spectral regions, including:

• Ultraviolet (UV) radiation – risk of skin damage and photokeratitis (corneal inflammation)
• Visible light – risk of glare and photochemical retinal damage (particularly in the blue-light spectrum)
• Infrared (IR) radiation – risk of thermal injury to the eyes and skin

Practical Application

For products such as luminaires, headlamps, work lights, or professional optical sources, photobiological safety classification provides important information for safe use and responsible product design.