Light pollution is perhaps the only one still growing exponentially everywhere. The growth should be slowed down and stopped and the trend reversed to achieve sustainable night environment. Reducing light pollution has similarities with the efforts to reduce fossil carbon emissions. Both pollutants have been considered harmless 30 years ago. Both are very dangerous. The common key solution is energy efficiency. But it won’t go successfully without legislation giving the effective rules, which could be as simple as:

Shine below horizon only. Use no more light than the standards demand. Ensure that the amount of light can be lowered at night substantially. Don’t use more then 1 cd/m² or 10 lux, if a safety standard does not apply. Put a limit for illuminated advertisements (like 200 cd for small surfaces, 300 cd for those over 5m² and 500 cd for those over 30m²). Apply emergency measures for the most vulnerable sites. Exceptions should be just traffic lights, short-time lighting, faint sources used by ordinary citizens.

Good experience from Lombardy, where such law holds since 2000. Need to document the
benefits. Failure of laws using just a declaration, including the Czech one. The rules should
be inside the very law, we hope to make it true in Czechia (http://svetlo.astro.cz/darksky/cz_law).

Reasons for demanding LPS, HPS or fluorescent sources.

Digital imaging photometry, glare quantification, road surfaces measurements, true amount of light at night (http://amper.ped.muni.cz/light/luminance), huge advantages of dimming the light sources (an example from Brno).

Possible opposition from industries wanting business as usual.

Sleep disturbed by light-at-night, vanished heavens (stars never noticed among strong luminaires), deprived childhood and rise of crime. Light does not help against crime, just dark hopefully. Bad rules worse than no rules at all. Good rules, like those in Lombardy, are a hope to restore the night again.

Jenik Hollan

Born December 3, 1955 in Brno, Czechoslovakia.
Studies of physics at the Masaryk University in Brno, Faculty of Sciences.
Since 1980, scientist and teacher at the N. Copernicus Observatory and Planetarium in Brno.
1994–2001 teaching astronomy also at Faculty of Education of Masaryk University in Brno.

Currently a graduate student at the Faculty of Civil Engineering of the TechnicalUniversity in Brno, investigating energy fluxes in advanced buildings and components of passive houses. Research in meteor astronomy and didactics of astronomy during the 80′s, then educating young people and general public on astronomy, on many issues of physics in everyday life and environmental problems (esp.global warming). Tens of his students are doing research in astronomy now.

Many lectures and texts on the prevention of light pollution and quality outdoor lighting (most of the existing Czech info, including the legislative proposals). Works from the last five years mostly available on the internet, on the light pollution at http://svetlo.astro.cz/darksky.