The wide and harmful reach of light pollution

Sarah Maguire
11 July 2018
Faculty of Science and Engineering


Light pollution is doing more than obscuring our view of the universe: it could actually be bad for our health.

There are eight billion people on the planet, and roughly one-third of them can’t see the Milky Way when they look up at the night sky.

This inability to see the galaxy that for millennia has fired humanity’s imagination and curiosity is the result of the electric lighting – on streets and in homes, across industry and commerce – that humans use to keep the dark at bay. And the widespread adoption of energy-efficient LED lighting has, ironically, made the situation even worse.

For astronomers like Dr Richard McDermid, a dark sky is all-important to their science. And it’s a no-brainer that the massive investment made to build and run observatories needs to be protected by keeping light pollution to a minimum in the areas where they operate. But, as the Macquarie University academic has discovered after looking further into light pollution, it has serious impacts right here on Earth that are only beginning to be fully understood.

“The impact of light pollution is surprisingly broad, touching on very disparate issues - ecology, marine biology, human health, urban development, cultural heritage, as well as astronomy,” says McDermid, a senior lecturer and ARC Future Fellow.

There is the obvious impact of energy wastage – “there’s really no reason for us to illuminate the universe,” McDermid says, referring to the significant amount of artificial light from human activity that is visible from space, and naming street lights and domestic skylights as among some of the major culprits. However, as humans light up the night to remove the limitations that darkness places on our own activities, animals that share our environment are affected, too.

McDermid uses the examples of creatures that use the darkness for camouflage and therefore become more vulnerable to predators in the presence of light pollution; and migratory birds whose transcontinental navigation systems get confused by the light concentrations of cities. Other behaviours are changed, too, such as that of baby turtles hatching on Queensland beaches which scuttle in the wrong direction towards the artificial light of coastal development instead of the celestial reflections upon the ocean.

Shift workers show impacts on health

In terms of human health, McDermid points to research linking diseases including cancer to shift work - which modifies the circadian rhythms of people who work at night and sleep during the day - and the prolonged exposure to artificial light that it involves.

“We don’t know how direct these connections are, but it’s something we need to pay attention to,” he says.  “Sleep is very important for our health. We’re generally becoming more aware of the impact of light on sleep patterns with the proliferation of mobile devices, and how using a backlit screen at night-time actually starts to interfere with our circadian rhythms and the triggers that our body looks for to know when to sleep.

“Light pollution interferes with the background of subconscious signalling that our brains receive, fooling us into thinking that it’s still daytime, so we don’t get sleepy.”

LED lighting dims the big picture

With light pollution only emerging in the past decade as a major area of research, McDermid is working to pull together a research project involving Macquarie academics across the relevant disciplines.

It comes at a time when LED lighting has intensified light pollution on two fronts, says McDermid. “It’s kind of a rebound effect,” he says. “Inprinciple, it's a positive move towards energy-efficient lighting; but because it makes it very cheap, lighting is now more prolific.

“And not only that, but most new LED street lighting uses a more damaging type of light – the blue light which is present in the whiter light of LEDs is more contaminating than conventional orange-coloured, low-pressure sodium lights, because it diffuses and gets spread out a lot more by the atmosphere.”

For McDermid as an astronomer, that brings the cultural importance of being able to see the night sky into focus.

“If we lose that ability to look at the night sky and appreciate its majesty, I think we start to lose a trigger to think on a bigger scale,” he says.

“An important part of what it means to be human is to see where we are in the bigger frame of things, and there’s no bigger frame than looking up at the dark night sky, staring into infinity, and being confronted by it.

“If you’re not confronted by it, then maybe you don’t think about it so much.”

Conference seeks to trigger search for solutions

Understanding the effects of light pollution, says McDermid, is the first step to taking action to mitigate those effects. And turning off the lights will not be the solution.

“It’s much more about our lighting practices, like minimising the upward spillage of light, directing lights accurately and appropriately, and only using them when needed,” he says.

In September, Macquarie will sponsor a conference on light pollution, ”Riding the Lightwave of Technology”, which will bring together ecologists, health professionals, astronomers, industry leaders, and the local community. They will gather during the annual ‘StarFest’ astronomy festival at Siding Spring Observatory on the edge of Warrumbungle National Park – home of the southern hemisphere’s first Dark Sky Park, which will be officially launched following the conference.

“If we want to change people’s behaviour, or impose restrictions or guidelines on how lighting is used, like generating any meaningful change it has to be well-motivated,” McDermid says. “The current task for research is to start documenting the wide-ranging effects of light pollution, communicating these broadly, and working with industry and communities to find positive solutions. That's the kind of progress and dialogue we want to trigger with this conference.”


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