The switch from street lamps to LEDs in many European countries has changed the color spectrum of night-time lighting – with possible consequences for people and animals. This is what British scientists write in the journal Science Advances. Using photos taken from the International Space Station ISS, they found that the proportion of emissions in the blue part of the spectrum increased as a result of the whiter LEDs. However, Germany is relatively unaffected by this effect.
Since blue light, for example, inhibits the release of the hormone melatonin, which promotes sleep, switching to LEDs (light-emitting diodes) can have an impact on animals and humans, explains the research team led by Kevin Gaston from the University of Exeter in Penryn. “The benefits that LED technology can bring to public lighting, and street lighting in particular, have been widely touted, with a focus on increased energy efficiency and the associated reduction in energy bills and carbon emissions,” the study reads. From the researchers’ point of view, the negative consequences for the environment should not be ignored. At the very least, the color spectrum of nighttime lighting should be measured regularly.
However, the researchers determined that only a small amount of local data is available on the color spectrum of light. The reason for this lies in the usual satellite sensors that are used to measure artificial lighting and only register the intensity of the light, but not its color. In addition, these sensors are hardly sensitive to the wavelength of blue light.
The ISS crew took 1.25 million pictures
Gaston and colleagues therefore evaluated photos taken by astronauts from the ISS. Around 1.25 million recordings have been made since 2003. The scientists selected images from 2012 and 2013 showing Europe at night and compared them with images of the same regions from 2014 to 2020. The boundary between the two periods marks the point at which LEDs are ready for the market as light sources for street lamps.