Photobiological safety of LED’s

Photobiological safety of LED’s

LED’s are more energy efficient and less operating cost than incandescent and florescent lightning system. Whether, it is our home or office , advancement in technology had replaced our old lightning systems to LED’s . They are semiconductor assemblies and has wide range of products from general to special lighting system. LED’s are like a cup of tea for advanced communication technology .

Benefits of LED’s

• Brightness
• Colour quality
• More light output that any other lightning system
• Long operating life
• Reduced or even eliminating the need of replacement
• Lower operating costs
• Energy efficient
• LEDs in screen displays reduces power consumption and prolong battery life in mobile phone,  tablets and other gadgets.

Hazards of LED’s on Humans

Optical radiation like UV, IR and EM  produced by LED’s shown risk to living human tissues mainly to eye and skin. In human the photobiological effects of light form LEDs affect skin, eyes and retina. Here is a list of some photobiological effects produced by LED

1. Photokeratitis: is a photochemical reaction When exposed to UV light from 200 – 320 nm and affects the cornea of eye of humans.
2. Ultraviolet erythema: is a photochemical reaction produces skin burns when exposed to UV light from 200-320 nm.
3. Ultraviolet Cataract: it affects the lens of the eye when exposed to UV light 290- 325 nm.
4. Photoretinitis: It is called blue light retinal injury caused when exposed to Visible light between 400- 500 nm
5. Retinal thermal injury : is a thermal reaction affects the retina and choroid of the eyes when exposed to visible light between 400- 1000nm.
6. Infrared cataract: is a reaction that affects the lens of the eye resulting in clouding of vision

Due to above photobiological risks associated with LEDs , Photobiological safety standards were developed that covers Lamps and Lamp systems , including LEDs. IEC 62471 was introduced in 2006 based on photobiological safety of Lamps and Lamp systems. An another standard IEC TR 62471-2 provides information on product labelling, user information statement, viewer related risk and occupational safety issues.

Paramenters measures by IEC 62471

1. Radiance : It measure the amount of actual light collected by pupil and evaluate the risk of hazards to retina.
2. Irradiance: It measures the total amount of radiation at an illuminated surface from entire hemisphere and evaluate the risk of hazards to skin and to the front of eye.