Tuesday, August 8, 2017

Cool blue or warm amber - If insects could vote.

The issues around light pollution are varied and when considered in relation to the ecosphere and biology can be quite different to the on going debate around the statement from the American Medical Association (AMA). Is it all about spectrum or do very particular wavelengths have a greater influence. On particular article that cycles around on website of Luxreview 'LED lights don’t attract insects. True or false?' makes an attempt to explain a few points and unfortunately doesn't get to a real conclusion. Other than it's probably pointless trying to conduct a scientific trial in your backyard. 
There's no shortage of research articles on the topic of light and insects. I think many of the researchers in this area would agree on one principal, that artificial light at night (ALAN) shifts the balance in the ecosystem and general creates a better environment for predators. If you're at the bottom of the food chain it's bad news. If as a human you're basically at the top of the food chain then the bad news is that ALAN may well attract nasty insects bearing disease. These ideas were published by 'Jari Lyytim¨ aki ' in 2013 in the paper "Nature’s nocturnal services: Light pollution as a non-recognised challenge for ecosystem services research and management" (Ecosystem Services).
Some recent research around moths suggests that populations of urban moths have reduced propensity to fly to light when compared to populations of moths in rural areas as found by 'Altermat & Ebert' in "Reduced flight-to-light behaviour of moth populations exposed to long-term urban light pollution" (Biology Letters 2016).
So a few months ago I was wandering around Brisbane one night, attending a conference by Institute PublicWorks Engineering Australia on ... whatever ... (I'd hasten to add that I'm not an engineer, I'm an IT consultant with a Masters in Illumination Design). I found an interesting piece of grass, I think it was nearby the Science Works museum. It was interesting because it had two types of lighting, high CCT and low CCT (see the header image). I think the luminaires were both LED but I can't remember now, and the close up images aren't revealing of the technology. Either way I'm not sure there's much difference. So to the images. The first image is of the small grassed park, the two types of luminaire are most definitely high CCT to the right ans low CCT to the left. I'm not too sure why this would be?
Grassed park area Brisbane showing high and low CCT luminaires

A close up of the high CCT shows a web of - well cob webs and plenty of insects.  In fact in this image it does appear that the luminaire may well be a LED package, there appears to be an array of square modules.
High CCT luminaire Brisbane Science Works
 A close up of the low CCT luminaire shows an absence of cob webs and no insects.  Is this surprising?
Amber (low CCT) luminaire BrisbaneScience Works
So - who has voted?