In the pages of the book “Polvo de estrellas” (Stardust), published by Thule Ediciones, Swedish author Hannah Arnesen reflects on the impact of human beings on planet Earth through stunning illustrations. Within its pages, there are excerpts from responses by a group of adolescent students to the question: “What do you miss in life due to climate change?” Two responses coincide in highlighting a particular issue. “Darkness,” says one. “Being able to see the sky. Where I live, there’s light pollution,” says the other.
This coincidence is not accidental. According to data from the report “The new world atlas of artificial night sky brightness,” published by the journal Science in 2016, more than 80% of the world’s population, and nearly 100% of the populations in the United States and Europe, live under skies polluted by light. This results in the Milky Way being hidden from view for six out of every ten Europeans and light pollution affecting 88% of Europe’s land area.
The Growing Threat of Light Pollution
Alicia Pelegrina, a researcher at the Institute of Astrophysics of Andalusia (IAA), reflects on the growing environmental problem of light pollution. She notes that each year, the illuminated area of the world and the intensity of artificial night sky brightness increase by about 2.2%. She emphasizes that light pollution is a rapidly growing global threat, supported by a study in 2021 by the Spanish National Research Council (CSIC) through the Quality Office of the IAA, which revealed a 50% increase in light pollution over the past 25 years.
Pelegrina argues that despite being a significant threat, light pollution is not perceived as such by the general population. Light is often associated with concepts like progress, wealth, security, beauty, fun, or well-being. However, she emphasizes that light pollution is pollution in the strict sense of the word and poses a threat not only to astronomical observations or ecosystem balance but also to human health.
Health Impacts of Light Pollution
Recent studies have begun to shed light on the health effects of light pollution. A study published in the journal Stroke, by the American Heart Association, for the first time correlates increased exposure to bright outdoor artificial light with a higher risk of stroke. The study, conducted in the Chinese city of Ningbo, found that individuals with higher exposure to outdoor nighttime light had a 43% higher risk of developing cerebrovascular disease compared to those with lower exposure levels.
Elena López-Cancio, secretary of the Stroke Study Group of the Spanish Society of Neurology (SEN), acknowledges the novelty of this study and its contribution to understanding new factors in stroke risk. She notes that previous research has linked outdoor nighttime light exposure to other health risks such as diabetes, hypertension, and circadian rhythm disruption, all of which are known risk factors for stroke.
Light pollution’s impact on the biological clock and sleep is particularly significant. Pelegrina explains that exposure to artificial light at night disrupts our biological clock and suppresses the synthesis of melatonin, the sleep hormone. Disruption of circadian rhythms and melatonin synthesis has been associated with metabolic disorders, cardiovascular diseases, cognitive impairment, mood disorders, and accelerated aging.
Mitigating Light Pollution
Despite these risks, there is limited awareness of light pollution and its health impacts. Pelegrina emphasizes the need for public awareness and action to mitigate light pollution. She suggests revising the use of artificial light, improving lighting efficiency, avoiding direct light emission into the sky, and limiting lighting hours in public spaces.
María Ángeles Bonmatí, a researcher at the Center for Biomedical Research in Fragility and Healthy Aging (CIBERFES), agrees that cities are over-illuminated and calls for urban planning that considers the real lighting needs. She emphasizes the importance of educating the public about the harmful effects of over-illumination and promoting sustainable lighting practices.
In conclusion, light pollution poses a significant threat to both human health and the environment. Addressing this issue requires concerted efforts to raise awareness, implement effective policies, and promote sustainable lighting practices. Only through collective action can we mitigate the adverse effects of light pollution and safeguard our health and the beauty of the night sky for future generations.
