Robert Gorter, MD, PhD, is emeritus professor of the University of California San Francisco (UCSF)
Light Pollution: more than 80% of the world’s population lives under light-polluted skies, causing immune suppression and cancer
Light pollution, also known as photo-pollution or luminous pollution, is excessive, misdirected, or obtrusive artificial light. Pollution is the adding-of/added light itself, in analogy to added sound, carbon dioxide, methane by cattle, etc. Adverse consequences are multiple; some of them may not be known yet.
Light pollution is a side effect of industrialized civilization. Its sources include building exterior and interior lighting, advertising, commercial properties, offices, factories, streetlights, and illuminated sporting venues. It is most severe in highly industrialized, densely populated areas of North America, Europe, and Japan and in major cities in the Middle East and North Africa like Tehran and Cairo, but even relatively small amounts of light can be noticed and create problems for humans and wild-life alike
Dr. Robert Gorter: “Light pollution is now a global phenomenon and disrupts the circadian rhythm in all humans in industrialized nations. Melatonin production becomes decreased and therefore, immune suppression is on the rise and the first signs are surfacing. Disruption of the circadian rhythm in humans, the incidence of chronic disease and malignancies are on the rise as a direct consequence of increasing immune suppression.”
Scientists explain in Science Advances how ground measurements and satellite data were used to create an atlas of a world brightened by artificial lights.
It reveals that the population of Singapore, Kuwait and Qatar experience the brightest night skies.
Conversely, people living in Chad, Central African Republic and Madagascar are least affected by light pollution.
Dr. Christopher Kyba, from the renouned German Max Planck Research Center for Geosciences in Potsdam, said: “The artificial light in our environment is coming from a lot of different things: “Street lights are a really important component, but we also have lights from our windows in our homes and businesses, from the headlights of our cars and illuminated billboards.”
The brightness map reveals that 83% of the world’s population, and 99% of Europeans and people in the US, live under skies nearly 10% brighter than their natural starry state.
The night is so bright that they use their color daytime vision to look up at the sky. In Singapore, the entire population lives under this extreme level of artificial night-time brightness, and it is a problem affecting many other parts of the world. 20% percent of the people in Europe and 37% of the people in the USA don’t use their night vision.
Dr. Gorter: “It is a growing problem due to the severe disruption (destruction) of the circadian rhytms of humans and animals alike.”
Dr. Kyba: “In the UK, 26% of people are using colour vision and not night vision.”
Dr. Gorter and his colleagues warn that nights that never get darker than twilight are affecting nocturnal animals, while in humans, the trend has been linked to sleep disorders and disease. Dr Kyba said that while lighting was important for development and safety, technology needed to improve. “There are a lot of street lights that are not particularly well designed,” he explained. “They shine light into areas that are not useful – so up into the sky, for example, isn’t really useful for anybody.
Light pollution, also known as photo-pollution or luminous pollution, is excessive, misdirected, or obtrusive artificial light. Pollution is the adding-of/added light itself, in analogy to added sound, carbon dioxide, etc. Adverse consequences are multiple; some of them may not be known yet. Scientific definitions thus include the following:
Light pollution is the alteration of light levels in the outdoor environment (from those present naturally) due to man-made sources of light. Indoor light pollution is such alteration of light levels in the indoor environment due to sources of light, which compromises human health.
Light pollution is the introduction by humans, directly or indirectly, of artificial light into the environment.
The first three of the above four scientific definitions describe the state of the environment. The fourth (and newest) one describes the process of polluting by light.
Light pollution competes with starlight in the night sky for urban residents, interferes with astronomical observatories, and, like any other form of pollution, disrupts ecosystems and has adverse health effects. Light pollution can be divided into two main types: Excessive light (generally indoors) that leads to discomfort and adverse health effects (like suppression of melatonin production).
Light pollution is a side effect of industrialized civilization. Its sources include building exterior and interior lighting, advertising, commercial properties, offices, factories, streetlights, and illuminated sporting venues. It is most severe in highly industrialized, densely populated areas of North America, Europe, and Japan and in major cities in the Middle East and North Africa like Tehran and Cairo, but even relatively small amounts of light can be noticed and create problems. Since the early 1980s, a global dark-sky movement has emerged, with concerned people campaigning to reduce the amount of light pollution. The International Dark-Sky Association (IDA) is one non-profit advocacy group involved in this movement.
Wildlife species have evolved on this planet with biological rhythms—changing that has profound effects
Artificial lighting seems to be taking the largest toll on bird populations. Nocturnal birds use the moon and stars for navigation during their bi-annual migrations.
When they fly through a brightly-lit area, they become disoriented. Birds often crash into brilliantly-lit broadcast towers or buildings, or circle them until they drop from exhaustion.
Over 450 bird species that migrate at night across North America and Europe are susceptible to collisions with night-lit towers, including threatened or endangered species.
“Seabirds are also at risk,” said Bill Montevecchi, a marine ornithologist at Memorial University of Newfoundland, in St. John’s, Canada. “Some, like the tiny Leach’s storm petrel, feed offshore on bioluminescent plankton—so are particularly drawn to light. The birds may be fatally attracted to lighthouses, offshore drilling platforms, and the high-intensity lamps used by fishermen to lure squid to the surface.”
For humans, the most worrisome insights revealed by the atlas are the effects of an ongoing shift to light-emitting diodes—LEDs—as sources of outdoor light over older incandescent illumination. LEDs are far more energy efficient, durable and dynamically adjustable than incandescent bulbs, and the U.S.A. and the EU and several other nations are aggressively incentivizing their use. The most economical LEDs, however, shine brightest in harsh blue-white hues. Because Earth’s atmosphere preferentially scatters blue light (for proof, just look up into a clear sunlit sky), Falchi’s model suggests that a large-scale conversion to cheap blue-white LEDs for outdoor lighting could substantially increase sky glow even if the total amount of emitted light remains constant. Besides being aesthetically unappealing to many people, there is concern that blue-white LED light may also be dangerous. Humans have peak visual sensitivity to the yellow and green parts of the visible spectrum, says George Brainard, a photobiologist at Thomas Jefferson University who was not involve with Falchi’s study. But it is blue-white light—exactly of the sort most produced by cheap LEDs—that dominates the regulation of human circadian rhythms and other important biological cycles,
Brainard says: “The wide-scale adoption of LEDs will reap huge energy savings, which is a good thing,” Brainard says. “The question is, are the great energy savings compromising human health and ecosystems?”
The problem is that the strong blue content of the white light in municipal LED installations scatters much more efficiently through Earth’s atmosphere, compared to other colors. “Models suggest that, when matched for the same total output of light, converting city lighting systems to white LED has the potential to significantly increase sky glow over cities,” says Barentine.
Why the big push for white LED lighting?
Many people believe that better visibility improves safety by reducing car accidents and criminal activity. Although this assertion seems reasonable, it is, however, false. No research data backs up these beliefs. Studies done in the UK, Chicago, and other cities confirm that no correlation exists between increased lighting and reduced car accidents or crime, including sexual assault.
What has been proven are the negative health and environmental impacts that can result from excessive lighting. Growing evidence shows that too much intrusive light at night disrupts our natural circadian rhythms, which can lead to fatigue and other serious health issues. For example, a study by Israeli researchers in 2011 showed that women who live in light-saturated neighborhoods had higher breast cancer rates, suggesting that excessive nighttime lighting (often from LEDs) interferes with the brain’s production of melatonin. The American Medical Association even issued a statement that “exposure to excessive light at night, including extended use of various electronic media, can disrupt sleep or exacerbate sleep disorders, especially in children and adolescents.”
Extensive evidence also shows that excessive artificial lighting disrupts the behavior patterns of nocturnal animals. LED lighting can interfere with their instinctual hunting and survival patterns, putting them at risk. “The various nocturnal species that populate our planet have spectral sensitivities to optical radiation different from those of humans,” says Rea. “For example, most nocturnal species have no long-wavelength-sensitive photoreceptors. Therefore, the impact of short-wavelength radiation could be more debilitating to these nocturnal species than to humans.”
Dr. Robert Gorter answers: “Yes, definitely and the first signs are surfacing. By disruption of the circadian rhythm in humans, chronic disease and malignancies are on the rise as a direct consequence of immune suppression.”