LED bulbs are the main culprits of light pollution. Scientists estimate that the market share of LEDs increased from “1% in 2011 to 47% in 2019” globally.
These results hardly surprise Olivier Hernandez, astrophysicist and director of the Planétarium Rio Tinto Alcan. “The switch to LED lights a decade ago had a detrimental effect. Since LEDs are economical and consume little energy, we tend to use more of them for lighting,” reports the astrophysicist. Light pollution would therefore be, in large part, the result of excessive and unnecessary lighting in cities and in certain rural areas.
In a technical report published in 2021, Olivier Hernandez and his colleagues focused in particular on sources of light pollution in the Montreal region for the period from 2012 to 2020. If the metropolis has adopted LED lights, it has however chosen not to use them at their maximum intensity. . “When Montreal made the switch to LEDs, we were able to convince them to opt for LED lights with 70% light intensity instead of maximum intensity. The city has made the right choices, because it has made it possible to reduce overall light pollution by 15% in Montreal,” explains Olivier Hernandez.
By examining satellite images, Quebec scientists have noticed that the greatest sources of light pollution come from, among other things, industrial parks and car dealerships. “Even though the municipal administration is making efforts to reduce light pollution, it does not control the lighting choices of individuals, private businesses, provincial highways, greenhouses, car dealerships, etc. “, enumerates Mr. Hernandez.
The dark side of light
Light pollution risks disturbing much more than our pleasure in observing the starry sky. It has physiological consequences on humans (such as the imbalance of the melatonin production), plants and animals. The authors of Science mention that the interactions between predators and their prey are likely to be unbalanced. Other studies have looked at the effects of light pollution on bird migrationon the reproduction of fireflies and on feeding in several species of insects.
A few ways to reduce light pollution
- Favor lighting directed towards the ground rather than towards the sky.
- Opt for warm colored lights.
- Use lower intensity bulbs.
- Control the lighting period according to the time of day.
