The shift to LED street lighting is producing more blue-light pollution – an important trend that has not been noticed by the specialized satellites that monitor nighttime lighting. That is the conclusion of researchers in the UK, who have analysed digital photographs of Earth taken by astronauts on board the International Space Station (ISS). The scientists say that the shift to bluer light is having negative consequences for human health, animal behaviour and astronomy.
LEDs have been around for sixty years, but older devices operated towards the red end of the visual spectrum. In the 1990s, however, bright blue LEDs became available – winning their inventors the 2014 Nobel Prize for Physics. The ability to create bright blue LEDs quickly led to the development of white LEDs, which are becoming ubiquitous in many lighting applications.
Indeed, LED streetlights have begun to replace sodium lamps – which produce yellow light – in many European countries. As well as offering lower cost and higher energy efficiency than sodium, LEDs provide better colour rendering, which improves an observer’s recognition of illuminated objects.