Illuminating the Issue of ‘Light Pollution’

Written by Daniel Silver

The notion that light can be a form of ‘pollution’ is relatively new. For millennia the word ‘light’ carried solely positive connotations. The Hebrew Torah begins with God creating light and declaring it good in Genesis 1:3. Influenced by this religious origin, light came to represent truth and reason in European philosophy, exemplified in the titling of the ‘Enlightenment’ movement [i]. Artificial light, used commercially starting in the late nineteenth century, was later associated with progress, with the rise of electric lighting coinciding with industrialization [ii]. Nighttime lighting was ubiquitous by the start of the twentieth century and, until recently, was considered wholly desirable [iii].

Today, nighttime darkness romantic and nostalgic appeal to many, embodying that which existed before human activities so dominated the planet [iv]. The first critics of injudicious lighting were naturally astronomers, cognizant that nighttime lighting inhibits one’s ability to view the cosmos [v]. However, concerns about anthropogenic lighting rose in prominence during the 1970s, in unison with increasing environmental awareness about global warming [vi]. Lighting was a conspicuous source of energy consumption and thus attracted scrutiny when energy conservation became a mainstream policy goal [vii]. The term ‘light pollution’ was also first employed by academics during the 1970s, starting with Rigel (1973)’s publication in Science, “Light Pollution: Outdoor Lighting is a Growing Threat to Astronomy”. Currently, the International Dark-Sky Association defines light pollution simply as “any adverse effect of artificial light”.

The scientific literature supports anthropogenic light’s designation as a ‘pollution’. Excessive light negatively affects human health [viii], harms wildlife by disrupting animals’ circadian rhythms and solar-based movements and migrations [ix], wastes massive amounts of energy [x], and degrades the night sky, an important cultural and aesthetic resource [xi].

Spider in the glare of artificial lighting. Photo by author.

In many cases, altering lighting design can inexpensively improve the illumination of an intended area, while simultaneously reducing unintended illumination, known as ‘light trespass’. Creative solutions to reducing light pollution abound. They include (1) Cut-off fixtures: lighting bodies that direct light from a lamp downwards (Lighting Research Centre);  (2) Computer Managed Systems (CMS): ‘smart’ lighting that can be operated remotely, enabling managers to more easily turn lights on and off [xii]; (3) Pre-programmed or motion-based dimming: reducing (or turning off) outdoor lighting during non-busy hours, usually through a CMS or a motion-sensor [xiii]; (4) and Warm-colored bulbs, which reduces the more harmful blue-light (IDSA). The usage of light-emitting diode (LED) bulbs is a more controversial solution. Though LED bulbs reduce cost and energy consumption [xiv], they tend to promote net increases in lighting due their lower cost [xv].

Example of different cutoff fixtures. Retrieved from

Despite being recognized since the 1970s, light pollution is still a very recent idea, and little is known about its social and ecological effects. Pioneer communities implementing strong light regulations generally have ecotourism-based economies that benefit from preserving a pristine dark sky. Such places have been largely successful in preserving their night sky, incidentally reducing energy consumption and benefiting their ecological and human communities at the same time. In Canada, the first ever Dark Sky Preserve was established in Torrance, Ontario, just two hours north of Toronto. Here, the Torrance Barrens Dark Sky Preserve was created due to strong environmental activism and advocacy. Gravenhurst and Muskoka Lakes, the municipal townships surrounding the Preserve, established by-laws to reduce the community’s light pollution. One of its main tenets is that all lighting must use cutoff fixtures.

By-law compliant lighting on Gravenhurst’s ‘Welcome Gateway’. Photo by author.

In my mind, the key going forward will be locating unneeded lighting, from both a spatial and temporal perspective. This necessarily entails engagement with residents to determine what classes of lighting people find necessary for safety. Existing technology can do much of the work from there. Though the Torrance Barrens municipal by-law approach is an excellent model from which other communities can draw, the question of who should be making decisions about lighting is still up for debate. Adjacent communities’ light may eventually encroach on the Torrance Barrens even though Gravenhurst and Muskoka Lakes regulate their lighting. Thus, light pollution may need to be regulated at scales broader than municipal governments if we wish to truly preserve the night sky in such areas as the Torrance Barrens.

 Ultimately, though the effects of artificial lighting and the loss of a pristine night sky may seem daunting, we can take solace in the fact that, unlike carbon dioxide, plastic, mercury, and all the rest, all we need do to eliminate light pollution is flip a switch.

52368359_2649483035091670_6546347946646962176_nDaniel is an undergraduate student at McGill University, majoring in environmental studies and minoring in organismal biology. He hopes one day to become a professor with a research agenda that focuses on conservation and ecology. In summer 2018, Daniel worked in the Torrance Barrens Dark Sky Preserve, surveying and interviewing local stakeholders about the Dark Sky By-law. Daniel’s work aims to illuminate (no pun intended!) what Gravenhurst and Muskoka Lakes do well in terms of dark sky preservation, as well as the areas in which they could improve. He hopes his results will help optimize management of the Torrance Barrens and offer insight to other communities around the world that want to take steps towards reducing light pollution.


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