Turn off light pollution, switch on the night

Light pollution under the spotlight

Light pollution manifests itself in the following forms:

Light trespass

Light trespass, also known as spill lighting, occurs when a light fixture casts illumination beyond its intended area of influence, and commonly refers to uncontrolled lighting affecting residences and wildlife habitations. This is common in Singapore and Hong Kong due to numerous streetlights and light fixtures in commercial and residential areas.

Glare

Commonly associated with unshielded light fittings, there are two types of glare: disability glare and discomfort glare. The difference between both types of glare is that the former can be dangerous causing the loss of contrast and visual acuity, which can lead to temporary blinding effects. For instance, disability glare can be a temporary loss of vision by approaching headlights from a vehicle when driving on a highway. Discomfort glare, on the other hand, creates an uncomfortable environment but does not necessarily impede vision or the ability to perform a task. An example of this can be overly bright streetlamps along the street.

Skyglow and light clutter

Skyglow occurs from both natural and human-made sources. Visible in cities around the world, human-made skyglow is largely caused by poorly shielded or controlled light that is dispersed upward into the atmosphere. In cities like Sydney, Singapore and New York, the night sky is almost invisible to the naked eye. Skyglow is closely related to light clutter, which refers to bright, confusing, and excessive groups of light sources in an area causing over-illumination that reduces the ability to view the night sky.

Impact of light pollution

All living organisms adhere to a circadian rhythm, a system that governs our sleep-wake cycles. For humans, our melatonin levels rise 10-fold in the evenings to promote sleep. Studies have shown that exposure to light during the night can cause sleep deprivation, fatigue, headaches, stress, and other health-related issues. Similarly, plants and animals also rely on the Earth’s cycle of light and dark to govern their behaviours such as reproduction, nourishment, sleep, and protection from predators.

The excessive use of electric light at night has negative and, in some cases, deadly effects on animals.

City lights have affected birds that migrate and hunt in the moonlight, causing them to wander off course and into cities. Every year, millions of birds die as they collide into illuminated towers or mistakenly migrate either too early or too late, missing ideal climate conditions.

In a 2016 study by scientists in the United Kingdom, four species of trees were observed. It was found that on average, electric light caused trees to bud more than seven days earlier^[2] as compared to other trees in their naturally occurring counterparts. This study bridges the relationship between the effects of excessive light and the timing when trees produce buds, thereby suggesting that light pollution is possibly causing spring to come sooner than it should. As a result, the trees’ earlier production of buds will have a knock-on effect on the animals and insects whose lifecycles are synchronised with the trees.

With increased artificial light, additional excess heat is also being generated, which further contributes to climate change^[2].

The onus to act

Given the severity and prevalence of light pollution, what can the public, governments and industry professionals do to reverse this trend? Fortunately, the solution is relatively easy.

At the individual level, one can adopt the following actions:

• Start by being conscious of our lighting needs and switching off all unnecessary interior and exterior lighting, particularly in our homes and office buildings.
• Reduce the use of blue-rich white light sources which cause glare and compromise human vision, especially to the ageing eye. These lights create potential road safety problems for motorists and pedestrians alike. In its place, one should use LED lights which reduce energy consumption and are environmentally friendly.
• Embrace the use of dimmers, motion sensors and timers. By doing so, one can decrease average illumination, glare, and light trespass.

On a global scale, cities have started to adopt legislation to control outdoor light. Canada introduced bird-friendly lighting (and construction) laws in the mid-1990s. Large urban cities such as Toronto, Washington D.C. and New York actively participate in lights out campaigns during peak migration seasons.

Countries like Spain and the Netherlands have also begun experimenting with motion-activated streetlights. As part of the Singapore Green Plan, authorities are reviewing the transformation of its current lighting assets, allowing the use of only authority-approved fixtures, and have set in place industry guidelines. Beyond legislation and policymaking, public education through workshops and lectures are also great avenues to build awareness within the community.

Ways to reduce light pollution

Here are some steps architects, designers, lighting designers and asset owners should take to reduce light pollution as they plan for lighting solutions on their projects:

Humans and animals have a longstanding connection with the night sky. The solution to light pollution does not necessarily mean a dim future. From the outset, qualified lighting practitioners should be engaged to undertake all aspects of lighting design. Collective efforts to decrease the excessive use of electric lights, review existing lighting assets and leverage software to create holistic built environment designs with sustainable lighting solutions are key steps in the right direction.

References

[1] Falchi, F., Cinzano, P., Duriscoe, D., Kyba, C. C.M., Elvidge, C.D., Baugh, K., Portnov, B. A., Rybnikova, N.A., & Furgoni, R. (2016). The new world atlas of artificial night sky brightness. Science Advances, 2(6).

[2] Zachos, E. (2016). Too Much Light at Night Causes Spring to Come Early. National Geographic, (6).

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Contributing author & reviewer: Farida Zohair