Light pollution is caused by excessive lighting and incorrect installation of luminaires. It not only affects astronomical observation. It has been internationally well reported that excessive number of artificial light points radiating indiscriminately in all directions exerts strong effects on the wildlife that lives around night and light cadence. Valencian natural areas, some of them near large population centres, are strongly affected by this problem.

The rapid introduction of LED technology into the public lighting in many Valencian towns, often using white light and therefore with a strong emission peak in the blue band, is going to increase very quickly light pollution and even to exert greater pressure on natural ecosystems and human health.

This paper presents measurements of night sky background obtained in natural parks and some areas of interest. It also detects and characterizes pollutant hot spots and the first effects of the cold LED lighting systems.

It has been shown that there are still some natural areas, such as the Natural Park Chera-Sot de Chera and the region of la Serranía, with excellent dark sky. These must be protected from future environmental assaults such as white LED lighting or flashing white light projectors for wind turbines.