Embracing the dark to beat light pollution

As International Dark Sky Week illuminates the issue of light pollution, Ellie O’Byrne talks to a group that says it’s not too late to save Cork’s night skies.
Embracing the dark to beat light pollution

A recent shot of Cork city from above at night. Picture: Enda Cotter

WHEN people think about pollution, they often imagine smoke billowing into the sky, or perhaps toxic chemicals leaking from pipes into waterways.

But light can be pollution too, and light pollution’s effects on animals and on human health are often overlooked.

It’s a modern phenomenon that has grown quickly worldwide, Cork Sky Friendly Campaign member Clair McSweeney says. And it’s a form of pollution whose negative side effects are often overlooked.

“We need to recognise the very severe impact that light pollution has on biodiversity,” Clair says.

“There’s a lot there about the migrating and breeding patterns of moths and insects, and about how detrimental the lighting of bridges is to fish migration.

“It’s all happened in this really short period of time, the past 200 years since industrialisation.

“Imagine that in such a short period of time, the humans on this planet have completely altered their relationship to the earth’s sky.”

Clair’s assertion that light pollution is occurring at an alarming pace is as true of Ireland as anywhere else on the planet: although the Emerald Isle has the darkest skies in Europe, light levels in Ireland increased by a staggering 60% in a period of development spanning less than 20 years, between 1992 and 2010.

For 13 years, Clair was the manager of Blackrock Castle Observatory, where her childhood love of stargazing and her work in educational programmes combined in a heightened awareness of how urgent the issue of light pollution is becoming.

“I grew up in a housing estate in the 1970s: I used to be out at night looking at the stars and Orion, Sirius and The Plough were common features in our lives,” she says. “We used to do a lot of camping and caravanning and I always loved sitting by the fire looking up at the night skies.”

Cork Sky Friendly Campaign (CSFC) was formed in 2017, and is made up of several astronomy and environmental groups including Cork Nature Network, Cork Architects Association, and Blackrock Castle Observatory as well as concerned citizens.

The technological advancement of LED lighting, which is capable of producing far more light for far less power, has been heralded as a way of curbing the energy usage, and therefore the carbon emissions, of public street lighting.

But it also means the potential for a lot more light pollution.

FIGHTING LIGHT POLLUTION: Cork Sky Friendly Campaign member Clair McSweeney
FIGHTING LIGHT POLLUTION: Cork Sky Friendly Campaign member Clair McSweeney

CSFC’s biggest success to date has been negotiating with Cork County Council’s Road Management Office, who have been charged with retrofitting public street lighting in Ireland’s South West, to ensure that the energy-efficient LED lighting being installed is of a specification that will not inadvertently add to light pollution.

“Energy-saving retrofitting is required across the board, because lighting is a huge amount of a local authority budget, the greatest amount, actually,” Clair explains. “Retrofitting street-lighting is a job that is happening around the country.”

“Blue-white LEDs at a luminosity of 4,000 Kelvins is just too much. If you can lower that to 2,700, you still have lighting without the extreme shadow play. You can have a lit environment without the negativity of light pollution.”

On top of concerns about the impacts of light pollution on biodiversity and animal life, human health impacts of blue spectrum light have been in the spotlight for the past few years.

“Blue spectrum light is dangerous for human health too,” Clair says.

“There have been loads of studies showing how lack of melatonin production and the disruption of our circadian rhythms is really detrimental to health.”

Cork Sky Friendly Campaign hosted an Ecowell event at Cork County Hall in 2019 that was attended by the Roads Management Office and Arup engineers.

“We were invited to a meeting afterwards and they have now changed the specifications on their tenders,” Clair says.

“The specifications have been reduced. I think that’s a really positive story, that change can happen.”

However, Cork city is not included in the county retrofitting roll-out plans, and Clair says that at this crucial juncture in the growth of the rebel capital, there’s “an opportunity to be an example of best practice in taking on this issue”.

She added: “It actually costs less money in the long run: the problem is that once LEDs come in, they don’t need replacing for many years so we need to act now to make sure they’re put in correctly in the first place.”

For many people, especially in urban areas, good street lighting is primarily a safety issue. But Clair says that, although it seems counter-intuitive, softer, dimmer lighting is actually safer than harsh LED blue-white lights.

“This is not a fight against light, it’s a fight against too much light, and a fight against light where it’s not needed,” she says.

“As a woman, I’m really conscious of the safety element.”

“The extremity of shadows created by these new glaring lights is actually more dangerous for women than the older, softer amber lights would have been, because they allow a throw that’s less shadowy. Less light can give the same amount of safety.”

Public lighting is one obvious source of light pollution, but homes and businesses have their own role to play.

A trend for homeowners to add lighting, both for aesthetic and security purposes, can take advantage of technology to ensure they aren’t adding to light pollution.

Members of the Cork Sky Friendly Campaign and Dark Sky Ireland at Vertigo Cork County Hall for the EcCoWell event ‘Bright Planning For The Urban Environment — The Dark Side of Illumination’. Front, from left, Clair McSweeney, Doroteja Repic, Georgia McMillan, Jack L (Lukeman), Ken Bond, Bernadette Connolly
Members of the Cork Sky Friendly Campaign and Dark Sky Ireland at Vertigo Cork County Hall for the EcCoWell event ‘Bright Planning For The Urban Environment — The Dark Side of Illumination’. Front, from left, Clair McSweeney, Doroteja Repic, Georgia McMillan, Jack L (Lukeman), Ken Bond, Bernadette Connolly

“Flood lighting goes everywhere,” Clair says. “We can use motion sensors to ensure we only have light when we need it, and with dimming and shielding and tilting, we can make sure the light is going in the right place.

“It’s still difficult to get the right fixtures and fittings off the shelf, but that’s changing. If there’s sufficient demands for those products, it will be easier to get them.”

In Cork, where a decade of development in line with Ireland 2040 plans to double the city are getting underway, Clair believes it’s not too late to start protecting our night skies with sensitive planning.

“We have so much to protect in Cork, and so little time with this mad pace towards growth,” she says.

“Ireland is rare in Europe in terms of dark skies, but you’re talking about in comparison with EU countries where you can’t see the Milky Way anymore. There’s an enormous amount to be said for the beauty and wildness that Ireland has, in this time of development, and it’s an opportunity for sympathetic change.”

International Dark Sky Week takes place from April 5-12.

Blackrock Castle Observatory, in collaboration with other members of Dark Sky Ireland, are hosting a range of events.

These are the links where the dark skies events are being shared:



Five night-loving creatures found in Cork city

Pipistrelle Bats Cork city is home to six bat species, with five species living near The Lough alone, but pipistrelles are the smallest and most common species and both subspecies, common pipistrelles and soprano pipistrelles, are found citywide.

White Ermine moths These spectacular cream-to-white coloured moths with characteristic dark spots and fairytale white fur mantle can be seen on summer’s nights between May and July.

Their caterpillars feed on ‘weed’ plants common to Cork including nettles and docks.

Foxes Urban foxes are surprisingly common and can thrive on the food waste opportunities cities provide, but prefer suburban areas of Cork where there is plenty of garden space to built-up city streets.

Hedgehogs Hedgehogs are another nocturnal mammal that can be found in parks and gardens around Cork.

The only Irish mammal to hibernate, these insectivores build ‘day nests’ to snooze during daylight hours and are even fond of napping in garden sheds.

Poplar Hawk-moths Very large moths, with a wingspan of 7-10cm. Their caterpillars feed on common trees like poplar and willow, before burrowing into the ground to pupate. Adult moths are camouflaged with grey-brown bark-like colouring. They can be seen between May and August

Light pollution Facts (via Dark Sky Ireland)

Light travels in straight lines, so unshielded light escapes into the night sky, contributing to light trespass (unwanted light in people’s accommodation) and skyglow, the glow seen over cities and towns.

Lighting levels in Ireland increased by 60% between 1992 and 2010.

There are now more than 480,000 public lights in Ireland. Powering them costs €56 million per year.

Lighting domestic homes in Ireland costs €233 million per year and generates 71,000 tonnes of CO2.

30% of the 210 gigawatts of energy used for public lighting in Ireland each year is lost as light pollution.

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