The persistent phosphorescence of europium-doped strontium aluminate particles has been investigated by optical microscopy observation in total darkness after exposing the material to very intensive visible lighting. Long-lasting phosphors, like the europium-doped strontium aluminate powder, have been widely used for green lighting applications. Lighting based on long-lasting phosphors allows minimizing electricity usage and decreasing the excess of light pollution. Both peoples and the surrounding ecosystems widely benefit of such a reduction of light pollution. As an example, these phosphors have been used for lighting around the Lowell Astrophysical Observatory (Massachusetts, USA). Indeed, astrophysical observatories require low lighting to properly see stars and often use the best practices in light-pollution safe lighting. Now this observatory is lined with paths that glow at night to allow researchers and visitors to safely find their way in the dark, without the use of bright electric lights (luminescence is more visible and healthier and people eyes get only a few more minutes to adjust to the dark)^[1]. There are many other places where long-lasting phosphors have been used for lighting. For example, bioluminescence can be observed around Puerto Mosquito, a bay on the Vieques island (Puerto Rico). The conservation trust took out electric lighting around this bay, which was negatively impacting the circadian rhythm of the glowing aquatic organisms. Tourists can still find their way from the parking to the bay by taking an installed path lit up with phosphors. A further example comes from street lighting like the bike paths in Lidzbark Warminski, Poland.