There are different types of pollution around the world, and in this case, we're going to talk about one that can't be seen or touched, but whose consequences are devastating for our health and the environment: light pollution . It's defined as the alteration of natural light levels, produced by artificial light sources generated by humans, and although it's not tangible, its effects are very real.
This type of pollution affects both biodiversity and humans, disrupting ecosystems and altering the natural life cycles of many species. In this article we will delve into what light pollution is, its impacts, and how it affects both people and other living beings.
What is light pollution
Light pollution is the alteration of the amount of artificial light in a place, exceeding natural levels. This alteration is mainly caused by the electric lights used to illuminate our cities at night. Although artificial lighting has a purpose, excess light generates negative consequences for both human health and ecosystems.
Many recent studies have revealed the extent of this problem. According to the International Dark-Sky Association, more than 80% of the world's population lives under skies polluted by artificial light. In some continents, such as Europe, this figure rises to 99%.
A more recent study also indicates that in the European Union , approximately 60% of the population cannot see the Milky Way due to light pollution. This phenomenon is even more visible in brightly lit cities, where the reflection of artificial lights off dust particles and smog creates a bright dome that blocks the night sky.
Furthermore, this pollution is not just a visual or aesthetic problem. Bright lights create interference that affects health, disrupting the circadian rhythm of humans and the life cycle of other living beings, as we will see later.
Impacts of light pollution
The impacts of light pollution are more profound than we can imagine. Many of these impacts directly affect humans and biodiversity. Let's categorize these effects and take a deeper look at them to understand their severity.
Light scattering
Light scattering occurs when particles in the air, such as dust or pollution, bend light in various directions. This causes widespread glare that affects the landscape for miles. Even on clear days, scattered artificial light can cloud the sky, making stars virtually invisible near cities.
This phenomenon is most evident in places where air pollution is high. The lights of large cities reflect off the pollution particles present in the atmosphere, creating that characteristic orange glow on the horizon that prevents us from seeing the night sky.
Excess artificial lighting
Excessive artificial lighting, present mainly in large cities, affects our natural cycle of light and shadow, causing sleep problems and an alteration in vital rhythms. The strong lights that invade residential areas from streets, street lamps and advertisements cause sensory disturbances in the inhabitants of these areas.
Constant exposure to artificial light sources has been linked to sleep disorders, such as insomnia. This is because light blocks the production of melatonin , the hormone that regulates the sleep-wake cycle in humans. A recent study revealed that excessive exposure to nighttime lights in people can disrupt circadian rhythms, which can trigger serious illnesses such as mood disorders, metabolic problems, and cardiovascular disease.
In addition, this excess of lighting can cause problems when driving, creating glare that affects road safety. Many drivers tend to feel safer on well-lit streets, which can increase the speed at which they drive, also increasing the risk of accidents.
Damage to biodiversity
One of the areas where the effects of light pollution are most alarming is in biodiversity. Nocturnal animals are particularly affected because their biological cycles are synchronized with the natural cycles of light and darkness. This light interference can disorient them and alter their behavior.
A clear example is migratory birds, which use the stars to navigate. Artificial light disorients them, causing them to lose their way and suffer fatal accidents when they crash into buildings. Likewise, constant lighting on beaches affects the reproductive cycle of species such as sea turtles. They confuse urban lights with moonlight, which prevents them from orienting themselves towards the sea when they are born, seriously affecting their survival.
In addition, the presence of artificial light disrupts the feeding cycle of many species. Fireflies and other insects, for example, depend on darkness for their mating rituals. Recent studies have shown that light pollution drastically reduces the population of nocturnal pollinators, affecting the pollination of plants and decreasing the production of fruits vital for the entire food chain.
In more complex ecosystems, such as coral reefs, artificial light also plays a negative role. A recent article in Philosophical Transactions of the Royal Society B highlights how excessive artificial light disrupts the growth cycles of marine organisms, jeopardizing key ecological services such as fisheries.
Other indirect impacts on ecosystems
As the direct impacts of light pollution become visible, we can observe other collateral effects. For example, the alteration of vital rhythms in insects affects not only their behaviour, but also the food chain, creating a “domino effect” in which different species are altered throughout the ecosystem. Nocturnal predators, such as bats, are affected by the reduction in the population of their prey, which alters the entire dynamics of the ecosystems that depend on these living beings.
Furthermore, artificial light inhibits melatonin production not only in humans but in many species, leading to immunological and metabolic problems. In environments affected by climate change, these effects are exacerbated, as species are already subjected to other pressures.
Prevention and mitigation measures
To reduce the impact of light pollution, several cities have begun implementing measures to control the use of artificial light. Among the most effective initiatives are the use of shielded luminaires , which direct light exclusively to necessary areas, instead of illuminating unnecessary areas such as the sky.
The effectiveness of dimmable LED systems has also been demonstrated , allowing adjustment to the specific light needs of each area, thus reducing the amount of light emitted at night in places where it is not essential.
It is important to note that some cities, such as Madrid, have already adopted regulations to reduce the intensity of public lighting by up to 50% at night, demonstrating that cities can be illuminated efficiently without radically harming the ecosystem or the population.
Implementing policies to turn off non-essential lights at night in residential and commercial areas has also proven to be an effective measure to reduce light pollution and allow nature to take its course during the hours of darkness.
Finally, initiatives like UNESCO's Starlight Declaration , which advocates for the protection of the night sky, have become vital for educating people about the importance of natural darkness. Raising awareness is key so that we can all work together to combat light pollution and its devastating effects.
Light pollution is an environmental problem that affects countless species and ecosystems, as well as having negative repercussions on human health. As cities grow, this problem also worsens, but through awareness and the implementation of more responsible technologies and policies, we can mitigate the damage and restore the natural balance of the planet.