A Case study of light pollution in France after the change in legislation

TL;DR

This study evaluates the impact of France's 2019 outdoor lighting restrictions on light pollution using GIS data, revealing a 6% decrease in annual light pollution and identifying potential Dark Sky Park locations.

Contribution

It provides an empirical assessment of legislation effectiveness on light pollution in France using satellite GIS data from 2012-2019.

Findings

Annual light pollution decreased by 6% after legislation

Strong correlation between population and light pollution (R≈0.83)

Potential Dark Sky Park locations identified in certain cities

Abstract

France issued a decree to restrict and prohibit mainly outdoor lighting effective from January 1st, 2019. Effectiveness of this legislation has been evaluated in this study using GIS data which was first used in \cite{2020MNRAS.493.1204A} (so called astroGIS database - \url{astrogis.org}). A subset of Artificial Light layer of astroGIS database has been adapted for years between January 2012 and December 2019. During 2019, radiance of $1.9 \times 10^{9}$ W cm$^{-2}$ sr$^{-1}$ has been released into space. Annual light pollution in France decreased by 6\% after the enactment of artificial light legislation. France continue to have potential Dark Sky Park locations for example cities like Indre, Lot, Nievre and Creuse having the lowest light pollution values. A strong correlation between population and light pollution ($R\simeq 0.83$) has been observed. A similar but a weak correlation can also be observed for GDP ($R\simeq 0.28$). However, it is still too early to justify whether the improvements observed in the dataset are due to the enactment of the legislation or not.