Abstract

Increasing studies report blue light to possess potential hazard to the retina of human eyes and secretion of melatonin. In 2013, blue emission from LED lamps was thought to be the blame to the discoloring of the priceless paintings by van Gogh and Cezanne. Electricity-driven white light that contains intensive blue emission has been increasingly adopted for general lighting since the invention of incandescent bulb 150 years ago. Contrarily, candles have been used since 5,000 years ago, and even much longer is the use of other hydrocarbon-burning lighting measures, including torches and oil lamps. Notably, candles and oil lamps emit little blue light. In addition to energy-saving, the call for a health-based light quality index by DOE in 2013 also spoke the need for a good light that is at least human-friendly.^[1]

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