From the perspective of space, the lights at night on earth have become more intense and decidedly bluer over the last 10 years. Astronauts on the International Space Station since 2012 have repeatedly photographed the earth with digital cameras, and have now documented the shift to bright blue-rich LED light.
By analyzing the digital camera spectra, a team of scientists from the University of Exeter in the UK and Complutense University in Madrid Spain, showed a 24% increase in blue light emission into the sky in Europe, largely from LED street lamps. That matches the rapid adoption of blue-rich LED streetlights since 2012. In the United Kingdom, 51% of street lighting was LEDs by 2019, and in Spain, 56% of were LEDs by 2017.
Besides having widespread effects on flora and fauna, and people outside at night in cities, blue rich light from street lights can enter bedroom windows and dose the occupants with harmful circadian blue.
This study was authored by Dr Sanchez de Miguel and his colleagues and was published in the journal Science Advances.