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Light pollution over Foothills County cooling as LED lights proliferate

The changing skies over northwest Foothills County have left some feeling blue.

The changing skies over northwest Foothills County have left some feeling blue.

That blue, said Dr. Phil Langill of the University of Calgary’s Rothney Astrophysical Observatory (RAO), has been a colour shift observed recently in the sky glow emitted from Calgary.

The likely cause is the shift from traditional high pressure sodium light standards to newer LED light, he said. 

Using the observatory’s AllSky camera that captures a wide-angle overview of the sky above, Langill observed a significantly bluer sky glow coming from the city’s direction.

He conceded that there are always several variables at play looking at images taken over long periods of time.

“It's not exactly an apples to apples comparison, but it certainly does seem to indicate a certain conclusion,” said Langill.

“If they could just cut down the blue, it would help a lot for anybody who's interested in looking at the sky at night.”

Stargazers aren’t the only ones concerned.

Laura Griffin, the Ann and Sandy Cross Conservation Area’s (ASSCA) nocturnal preserve lead, said blue light has the potential to significantly disrupt wildlife.

She cited reports by the American Medical Association that state cool blue light can be detrimental to health.

The reports associate lights that emit a cooler blue — those with a Kelvin value greater than 3000K — with various ill effects on human health, such as negative effects on circadian rhythm and metabolism.

Light with a Kelvin value of 4000K or more, which give off a cooler blue light, has a shorter wavelength that allows it to scatter more in the atmosphere.

A 2016 report by the American Medical Association states blue wavelength light “further contributes to disability clare, i.e. visual impairment due to stray light, as blue wavelengths are associated with more scattering in the human eye.”

It goes on to state that excessive blue light is environmentally disruptive for nocturnal species.

A new development on the southwest edge of Calgary adjacent to the ring road, dubbed Alpine Park, was a cause of concern for the County stakeholders 

Langill learned, however, that the Providence Area Structure Plan (ASP) which covers the development, is the first Calgary ASP with language restricting light pollution, and directly references the observatory and ASSCA.

It states “Because of proximity to the Rothney Astrophysical Observatory and a nocturnal preserve, a luminaire Backlight, Uplight and Glare value of 0 should be used, in consultation with The City of Calgary’s Roads department.”

A statement from City of Calgary spokesperson Sherri Zickefoose mirrored this regard for the City’s neighbours.

“City of Calgary is working with various stakeholders, including the University of Calgary, to mitigate light pollution and preserve dark-skies in the Providence area due to its proximity to a nocturnal preserve and the Rothney Astrophysical Observatory (ROA). 

“As identified in the previously developed Area Structure Plan (ASP), light pollution is a significant concern in the Providence area and the City of Calgary is committed to implementing best practices and innovative technical solutions to minimize light pollution to the greatest extent possible," she said in the statement. 

Zickefoose added the City is uses primarily 3000K lights (referred to as luminaires) in residential, collector, and some major roads, and are using 4000K lights on major roads, but mostly 3000K. 

“We have target illuminance and uniformity of light ratios that we aim to meet on all new roadways,” she said in the statement. “As we issue new contracts annually for luminaires, our specifications (including colour temperature) are reviewed and we adjust based on what is available on market.”

Calgary street lights feature full cut off photometrics and Dark Skies certifications in an effort to reduce skyglow and to optimize illuminance levels for the pedestrian and vehicular environment, the statement adds.

“The luminaires we are using are safe and appropriate for use in Canada,” Zickefoose said.

Fortis Alberta, which maintains street lights in much of rural Alberta, has been using 3000K lights since 2017, according to spokesperson Alana Antonelli.

Foothills County Reeve Suzanne Oel said in a statement she looks forward to further consulting and working with the City to ensure preservation of the night sky.

“We hope that the City of Calgary will follow through on using Dark Sky principles, policy and design guidelines for street lighting, as indicated in the Providence ASP, because this could be an inspirational urban development if the outcome is that a reduction of light pollution and impact mitigation is achieved,” Oel said in an email statement.

“This good-neighbour effort would respect a lot of surrounding, affected landowners and organizations.

“We look forward to communications to invite participation in the development permit stage from the UofC’s RAO, one of the County’s Dark Sky Initiative partners.”

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