Lighting brings a sense of safety and security to cities and communities… However, excessive or ineffective lighting… is detrimental to the health of the city dwellers and to the environment
Urban lighting is, as Harry Verhaar explained in a previous article, a key aspect for the success of cities. Lighting brings a sense of safety and security to cities and communities, and proper urban lighting can also bring several benefits to these areas, from social to financial ones.
However, excessive or ineffective lighting also comes with its disadvantages: it is detrimental to the health of the city dwellers and to the environment. It disrupts sleeping patterns, it creates hyperactivity, and light exposure at night may even increase the risk of cancer. Poor lighting also has a negative effect on wildlife. It unbalances fauna’s biological cycles; birds, bats, and insects get confused by the artificial lights of urban areas and eventually die from various reasons linked with light. An excess of artificial light results in what is called “light pollution”.
One of the most notorious effects of light pollution is the “sky glow”. This phenomenon appears when urban lights are directed towards the sky and are reflected into the clouds at night. The result can be seen as a yellow layer of “smog” hovering over the city. But it is not necessary to see this yellow layer. Just try to remember when was the last time you saw a starry night; whenever you cannot see stars, it means that the sky above you is polluted with urban light. Light pollution is not only caused by street lighting, but also by lighting in houses, skyscrapers, stadiums, advertisements, etc. The sky glow effect is mostly due to light emitted above a 90-degree angle, towards the sky, which means that the sky is directly being illuminated by these light sources. This results in a massive waste of energy as well. Many of the street luminaires are designed in such a way that they direct the light to the sky.
We can have proper lighting without the pollution it creates.
However, we just need to remember that these lights are mainly there to make people feel safe and to reduce criminality, but as the International Dark-Sky Association (IDA) Nevada Section Leader Maggie Tracey once stated: “Crime is not reduced by sending light upward into the sky or by sending glare into your eyes.” This means that streets only need to have lights that are directed towards specific areas, lights that do not produce glare, and that do not create shadows in particular points. With these three criteria, light pollution can also be reduced.
In the United States, the IDA has recently developed a Model Lighting Ordinance. It is a set of specifications that can help reduce light pollution. The ordinance states that luminaires such as barn lights, non-shielded wall packs, and floodlights or lights not aimed downward have to be avoided. Therefore, the luminaires should be fully shielded in such a way that no light escapes above a 90-degree angle. This allows to aim the light into a particular spot, instead of spreading it upwards. The fully shielded lighting also ensures that glaring is decreased, which is also safer for pedestrians, particularly in junction areas, because in this way, pedestrians will not be blinded by the glare. In addition to these benefits, this type of luminaires represent great energy savings, because only the necessary light is used towards the specific points that need to be illuminated, instead of illuminating the sky.
Light pollution can also be reduced with non-tangible measures. In some countries, for example, street lights are dimmed after midnight, when they are not really used, and these measures don’t put into risk the safety of the places.
In the end, everyone needs proper lighting for safety, happiness, and wellbeing. However, as all the good things, it should not be used on an excessive scale. We don’t need to sabotage wildlife or our own health to have safe and vibrant cities. We can have proper lighting without the pollution it creates. Urban lighting is yet another aspect of our civilization that can have a more harmonious relationship with our natural environment.