Law on Air Quality and Protection of the Atmosphere

Art.3 (f) "Light pollution": The nighttime luminous glow or brightness produced by the diffusion and reflection of light in gases, aerosols and particles suspended in the atmosphere, which alters the natural conditions of nighttime hours and possibility of astronomical observations of celestial objects; and the natural brightness, attributable to the radiation of celestial sources or objects and the luminescence of the upper layers of the atmosphere, must be distinguished from the luminous glow due to the light sources installed in the exterior lighting