The night sky is getting brighter, and it’s doing so at an increasingly rapid pace. The number of visible stars has significantly decreased, and according to research, this decline is linked to a 7-10% annual increase in sky brightness within the human-visible spectrum. However, this isn’t merely a side effect of progress. On the contrary, technological innovations can help reduce light pollution through more efficient lighting that minimizes the unnecessary dispersion of light.
To delve deeper into this important topic, we interviewed Matteo Seraceni, Technical-Scientific Director of AIDI – the Italian Lighting Association. With him, we’ll explore what light pollution is, its causes, and potential solutions.
This is an excellent question because different phenomena are often confused with one another. To be precise, we must first of all establish a distinction between “astronomical light pollution” and “ecological light pollution.”
“Astronomical light pollution” refers to the decrease in our ability to observe stars due to increased night-sky brightness* (the background luminosity) caused by artificial light sources. Every star in the sky has a specific brightness (known as “magnitude”): if a star’s brightness is close to the background one, then the star becomes invisible because the contrast is too low.
Astronomical light pollution is primarily caused by poorly oriented or oversized lighting luminaires that exceed actual needs.
“Ecological light pollution,” on the other hand, refers to any negative effects on humans or the environment caused by misused artificial light sources. Its impact depends on several factors, as different species are sensitive to various bands of visible and non-visible light radiation. Additionally, the period and duration of exposure are also important. De facto, any artificial light can be a potential source of ecological light pollution.
Unfortunately, we make very little use of the potential offered by light – both natural and artificial – which results in waste and pollution.
In the outdoor environment, lighting is often viewed as a deterrent to crime, a tourist and commercial attraction, or even an aesthetic enhancement. While light can serve all these purposes, it is much more. Just as a light bulb is not merely a bulb – try changing the position, type, intensity, or color of a light source in any room and see how it transforms the perception of the space and the associated mood.
The best antidote to light pollution is fostering a “culture of light”, meaning the ability to use this extraordinary medium to improve the quality of our lives and the surrounding environment.
Astronomical light pollution has no direct health consequences, but losing the ability to see the stars represents an immeasurable loss for humanity.
As for ecological light pollution, relatively recent discoveries reveal that our eyes contain receptors which are not used for vision but for regulating the circadian rhythm – the daily wake-sleep cycle.
Humans evolved to live outdoors and be active during daylight hours, meaning exposure to abundant light during the day and darkness at night. Today, we do the opposite: we stay indoors during the day, where light levels are significantly lower than outdoors, and are exposed to intense artificial light sources at night (such as work-related lighting or screens). This could alter circadian rhythms.
Numerous studies have found a strong correlation between circadian rhythm disruption and metabolic disorders or the development of various diseases.
The human species constantly alters the ecosystem it inhabits. Unless we eliminate our presence entirely, environmental influence is inevitable.
A striking example is Chernobyl: the 1986 nuclear disaster caused thousands of cancer cases, turned a populated area into a ghost town, and rendered 2,600 square kilometers uninhabitable.
However, 40 years after the departure of humans, many plant and animal species are more abundant than before. Even in the areas where radioactivity is at its maximum, vegetation recovered within a few years. Despite the damage, the nuclear disaster was less devastating for the local ecosystem than human activity.
This does not mean that we have free rein, because whatever we do alters the natural balance – but neither does it mean that we should assume that we cancel any artificial device, including light.
It depends on how we define “economic benefit.” If we mean monetary profit, then it’s all worth it: in Las Vegas, increased light pollution generates wealth.
However, if we broaden our perspective to a different concept of economy – regenerative and circular (such as the principles of the European Green Deal) – it becomes clear that optimizing energy consumption fits with the main rule against light pollution: illuminating only what is needed, when it is needed, and no more than necessary.
This is relatively straightforward because, in Italy, most light pollution does not come from public lighting, which has been strictly regulated for over 20 years.
A public lighting system designed by a professional, following industry standards and using the latest technologies, minimizes environmental impact.
The best way to reduce light pollution is to turn off lights when they are not needed. Today, we have LED sources that can be dimmed or turned on and off at will. Adding sensors to detect activity near light sources and intelligent control systems provides all the ingredients to create a lighting system that adjusts to actual needs at any time without waste.
Not only does this reduce light pollution, but it also cuts energy consumption and CO2 emissions.
Yes, and the most interesting aspect is that this change is evident primarily at two extremes: the supranational level (e.g., the European effort to regulate environmental issues) and the local level (where citizen associations actively discuss and propose solutions).
The mindset that “a light bulb is just a light bulb” (you can replace “light bulb” with terms like “electrician,” “lighting designer,” or “luminaire”). We need to improve how we communicate the importance of light in our lives and, consequently, the need to use the best tools and professionals.
* Note: The night sky naturally has brightness due to the moon, dust, and other non-anthropogenic phenomena. For example, during full moon nights, it’s challenging to distinguish stars even in areas far from artificial light sources.
Matteo Seraceni, Technical-Scientific Director of AIDI – the Italian Lighting Association
