74|A FONDO Mapa de polución lumínica, Cizano Falci In 1877, the first electric luminaries were installed in an urban space in Europe, in front of The Opera in Paris. In Latin- America, the first country to install electric light was Costa Rica, in 1882, while in Chile, it was 1883 when the “Plaza de Armas” in Santiago, was illuminated. It could be stated that the XXth century began with most major cities illuminated by electric light in squares and important places of the public urban space. But it’s in the 1950’s when urban lighting becomes massified, under the concept of light in street and traffic areas, as we know it today. This came as a consequence of the massification of automobiles, construction of highways and the new concept of urban development based on vehicle mobility. This lighting model still pre-vails today: Light’s destiny is the automobile and not the people that inhabit the public spaces. In the 80’s the concept of light pollution was coined due to the loss of the starry night sky. The light emitted by a city beyond its limits can reach a radius of 40 km. Light Pollution is becoming a cause for concern, not only for astronomers, but in relation to the loss of night flora and fauna, energy waste, and the importance of darkness in the circadian cycles and its effect on human health. Commercialization of the efficient white LED began in 2005. It reached 70 lumens per watt, which allowed substitutions of discharged light technology. White leds, today, border the 100 lm/W in warm light as well as in cold light. This technological development in lighting opens up the possibility of designing the public urban space using the visual criteria characteristic of our profession; understanding that light used in excess, indis-criminately and where is not needed is not a good thing. LED threat: 6000 Kelvin and over lighting The industry of LED arrived as an avalanche of savings promises for the mass substitution of millions of lu-minaries. But blind substitution, without design, under the premis that “energy savings” is the only virtue, would be a historical waste. The opportunity of improving people’s quality of life; revitalizing public spaces through design; and the possibility of implementing regulations and controls of intensity, color, tone, direction and alignment that the new technologies have to offer, would have been thrown away. Health Those of us, who work in lighting know that the white Led is really a blue Led of 450nm, and a phosphoric filter. Hence, cold light white Led is cheaper to produce because the blue filter removes less blues. It also has lower chromatic reproduction than the warm light Led. Concerning visual perception, we also know that, night vision is extremely sensitive to contrasts, and that 1 lux is the equivalent in light, of what we perceive on a clear night with a full moon; twilight is 3 lux. We have some knowledge on the circadian cycle and its relationship to light. For example, blue light (450 nm), above 10 lux interrupts or changes the production of melatonin during the night. Therefore, why isn’t a regulation to fix night illumination of public places at a maximum of 10 lux and a mini-mum of 3 lux? These would be levels planned respecting people’s health and not for maneuvers of automo-biles. Some regulations ask for a minimum average of 20 lux in streets with pedestrians and automobiles. Consid- ering that automobiles have their own light, isn’t it excessive? And, if blue frequencies (450 nm) are not healthy when used daily, why isn’t warm light, of 2400 Kelvin to a maximum of 3000 Kelvin, promoted for urban lighting? On the contrary, cold light is advertised with a slogan implying that it improves color apprecia-tion, when we know warm light offers better chromatic reproduction.