Zoological lighting specialist warns that LED street lights could lead to a loss of biodiversity.
Light-emitting diodes (LEDs) pose a serious threat to biodiversity and should not be specified for outdoor environments, a leading animal welfare expert and architect has warned, writes Stephen Cousins.
LED bulbs are more energy-efficient than traditional incandescent bulbs and are now being used to replace sodium vapour lights, commonly used in street lighting. The original inventors of the technology even received a Nobel Prize in Physics last month.
But according to James Karl Fischer, managing director of the Zoological Lighting Institute (ZLI) and president of the US branch of the RIBA, LEDs disrupt the “photo diversity” of nocturnal environments, which include a range of natural light conditions such as clouded night, starlight and moonlight. This ultimately leads to a loss in biodiversity, as the habitats that support wildlife become restricted to a limited range of conditions.
LEDs also attract unnaturally large swarms of insects in developed areas, increasing the chances of disease spreading, he said, and removing important food sources from mammals in the wild.
"Reducing exterior artificial lighting is a must to allow the complexity of nocturnal environments to flourish. If LEDs have to be used, shielded light fixtures should be specified."
James Karl Fischer, ZLI
“Fluorescing LEDs [that emit a broad range of frequencies] are a huge threat to biodiversity, they disturb animal physiology, making it necessary to avoid their specification in outdoor environments altogether,” said Fischer. “Reducing exterior artificial lighting is a must to allow the complexity of nocturnal environments to flourish. If LEDs have to be utilised outdoors, shielded and bollard light fixtures should be specified to restrict intrusion by insects. Light should only be cast where humans need to see, and as minimally as possible to allow animals’ eyes to adjust to starlit environments.”
The warning came following the publication of a report, by New Zealand-based research institute Scion, which found that white LED bulbs attract 48% more insects than sodium vapour lights. Researchers, led by entomologist Stephen Pawson, said the effect potentially disrupts the food chain by causing flies to be thrown off their usual path and into the jaws of predators. Insects are attracted to white and yellow light, but evidence suggests they are even more attracted to the short wavelength blue light generated by all LEDs.
ZLI has conducted its own research into the effects of external artificial lighting on animals. “A prime concern is ‘photo-taxis’ whereby animals are attracted or repelled by artificial light, which leads to concentrations in developed areas, where there should not be,” said Fischer. “Artificial light has been shown to disrupt creatures’ hormone cycling and production, visual cues related to foraging and breeding and causes timing issues inherent to the daily, monthly and seasonal interactions of animals.”
When any type of artificial lighting is specified for outdoor environments, ZLI recommends that designers restrict output to a very narrow band of frequencies to reduce the potential impacts.
ZLI has also urged manufacturers to produce a range of LEDs with filters that emit light in different frequencies to allow designers to specify products that will not impact on key local species and their critical co-species.
