Light pollution, one of the great environmental disasters of the last 50 years – astronomer


By RNZ

Light pollution is one of the great environmental disasters of the past half-century, all the more insidious because many people are completely unaware of the problem, says famous astronomer John Hearnshaw.

Astrotourism is a fast growing niche tourism industry around the world, and New Zealand, with five Dark Sky Sanctuaries, is playing a leading role.

Professor Hearnshaw has just launched the Aotearoa Astrotourism Academy, a school to train budding astrotourism guides. He is also about to release the New Zealand Dark Sky Manual, a manual for those interested in dark sky protection.

Globally, light pollution is increasing at a level of 2% per year, so the skies are getting brighter, he said.

Light pollution makes people sick and affects the environment, Professor Hearnshaw said.

“It makes people sick because the blue light from the new LED street lights disrupts our hormones and especially melatonin and melatonin are only produced at night in the absence of blue light.

He said there was a lot of “light breach”, where street lights shine through the windows of people’s rooms – which is very damaging to their health.

“It is well known that if you disrupt your hormones with blue light it increases hypertension, it causes depression, it can even lead to suicidal tendencies, so blue light at night is very serious.”

He said that while any blue light can cause health problems, “the real bad guy is the new LED, that is, the light emitting diode, street lights that have a strong blue component.”

They are mainly replacing high pressure sodium lamps which have a very orange color with very little blue, he said.

Professor Hearnshaw said this happens because LED lights can produce a lot of light for little electricity and are low maintenance.

But he said they should be replaced with a new type of LED called Amber Phosphor Conversion LED.

“It turns a lot, but not all, of the blue light into a more yellow light, so the warmer, orange-colored LEDs are now available.”

This type of more amber LED is installed in the Mackenzie District around Lake Tekapo and the Mount John Observatory, Professor Hearnshaw said.

He originally said it was in an effort to tackle light pollution because it’s bad for astronomy and the Mount John Observatory is very close to the village of Tekapo.

Professor Hearnshaw said a lighting ordinance was introduced into the Mackenzie District Council’s district plan to help astronomy, but light pollution is often combated now because people recognize its damage to the environment and to human health.

“But most of New Zealand, and indeed most of the world, gets rich blue LEDs.”

He said these should be replaced with the more amber LED type, which is unlikely.

LED lights can be dimmed or turned off by a central computer control system and if dimmed it would reduce light pollution, he said.


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