Are you able to see stars at night? With 80% of the world living with light pollution (Falchi et al., 2016), chances are you cannot. Not being able to see stars… is a pity for sure, but light pollution has more detrimental effects than just blocking our stars (which by the way to astronomers is a big problem). In this post, let us learn more about light pollution and what we can do about it!
Light Pollution
World map of artificial sky brightness (Source: Falchi et al., 2016)
Light pollution refers to the excessive use of outdoor artificial light which leads to the phenomenon of skyglow – the artificial brightening of the night sky (National Geographic, 2022). Light pollution is especially prominent in cities, where the day never ends and the nightlife an attraction on its own. In Hong Kong, measures of night sky brightness revealed that the night sky of Hong Kong was 1000 times brighter than it would have been without artificial life (Bramley, 2014).
By population, Singapore is the most light-polluted city in the world, with 100% of the population never activating their nighttime vision (Figure 1).
Figure 1: Different extents of light pollution (Panko, 2016)
From the Atlas, we see the extent to which light pollution is prominent in the world and how many people have been robbed of the opportunity to enjoy the natural night sky and even of their health.
Negative Effects of Light Pollution
Of the many victims of light pollution, the consequences of excessive exposure to artificial light are well-documented in animals and their natural behaviours. Chepsesiuk (2009) lists many examples, including female sea turtles which become disoriented when approaching beaches to lay their eggs due to the artificial lights and baby sea turtles similarly being unable to reach the sea as the typical “elevated dark silhouette of the landward horizon” is missing. Even trees are affected by light pollution – studies have shown that prolonged exposure to artificial light causes trees to be unable to adjust to changes in season, which has wider consequences for animals which find their habitats in these trees (Chepsesiuk, 2009).
Needless to say, the negative impacts of light pollution are significant in humans as well. The circadian clock, an internal 24-hour body clock largely affected by sunlight and nighttime darkness, can be disrupted by excessive artificial light which can lead to a variety of health problems including sleep disorders and even increased risks of breast and colorectal cancer in those with night shift work (Chepsesiuk, 2009). Significantly, melatonin production is reduced when exposure to light continues at night, resulting in less sleep, fatigue, stress, anxiety and more (National Geographic, 2022).
What can we do?
Gaston et al. (2012) detail various ways in which the negative impacts of light pollution can be reduced. One most obvious way of doing so is to reduce the use of artificial lighting and instead leave pockets of dark areas in the city. In most cities, there are already small dark regions with few streetlamps which often comprise areas with vegetation and natural landscapes (Gaston et al., 2012). By targeting and expanding these areas, the reach of light pollution can be limited to places which need artificial light, for example, roads. Furthermore, with light pollution increasingly prominent, cities and communities with places where the night sky is visible are becoming more attractive as people recognize the practical and arguably spiritual benefits of the dark night sky. The city of Jasper in Alabama has hosted Dark Sky Festivals since 2010 which have generated much and where stargazers can drive a few minutes from the town to see night sky wonders (Drake, 2019)
Furthermore, with the aim of lowering light pollution within the city, white-light LEDs, which are common globally for being efficient and extremely bright, are slowly being replaced with shielded LEDs with lower temperatures and less harmful blue wavelengths (Drake, 2019; Figure 2). This is again a practical step that cities can take, in addition to lowering street lamp poles and directing light downwards (Figure 3), to limit the reach of artificial light at night (Gaston et al., 2012).
Figure 2: Before and after the city of Dunedin, New Zealand changed its LED lights to shielded LEDs (Source: Earthly Mission, 2021)
Figure 3: Street lamp design can reduce light pollution (Source: Montjoy, 2022)
Stars (quite literally) only shine in the dark
An abundance of artificial light at night today is a sign of progress and prosperity for many cities in the world, but let us not blind ourselves in our pursuit of growth and forget to appreciate our natural wonders.
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