Artificial light can attract insects carrying deadly pathogens—a big concern in developing nations. Can customized LEDs help?

Artificial light: It stresses our eyeballs, fiddles with our biological clocks, and may even contribute to obesity. These are just a few of the health concerns associated with indoor lighting in the developed world.

But in warm, developing countries, light bulbs can be literal beacons for human disease when buildings aren't uniformly equipped with screens or glass windows. In Brazil, for example, a fluorescent light can invite deadly pathogens on the backs of mosquitos, sandflies and more. Chagas disease, leishmanias, and malaria are all diseases transmitted by insects, whose attraction to light—especially to the blue and ultra-violent end of the spectrum—is well documented. According to the World Health Organization, some 584,000 people die of malaria alone each year.

But new developments in LED lightbulbs mean that artificial lighting could be customized to discourage insects, says Travis Longcore, associate professor of spatial sciences at the University of Southern California.

Although LEDs have a reputation for harsh, blue light, some new ones come with four color diodes: Red, blue, green, and white. The combination of these wavelengths gives off "full-spectrum" light, which is ideal for indoor activities like reading, drawing, and watching TV. But the individual diodes can be manipulated to create a different mix of wavelengths, while still appearing white to the human eye.

"Most forms of artificial lighting have a spectrum that's pre-determined by the way you make the light," says Longcore, referring to fluorescent and incandescent bulbs. "But with LEDs, you can decide what combination of spectral output you want."

Captured insects (courtesy of Travis Longcore)

In a collaborative study with André Barroso, a senior scientist at Philips Research in the Netherlands, and a group of UCLA undergraduates, Longcore essentially "turned down" the blue and green diodes on a few custom-made LEDs, and compared how many insects were attracted to these bulbs versus off-the-shelf fluorescents and LEDs. All of the bulbs gave off light that looked "white," but the wavelength combinations were different. Sure enough, the team found that the custom bulbs that minimized blue and green wavelengths attracted about 20 percent fewer insects.

"We don’t know that this is necessarily the best configuration of wavelengths, because this is the first time that people have tried to do this," says Longcore. "What this does say is that there's an opportunity with LEDs to make light the way you want it instead of the way the lamp has to have it."

It's a big first step towards developing a safer bulb that deters as many vectors (disease-transmitting organisms) as possible, though different insect groups are likely drawn to slightly different wavelength combinations.

"In the tropics, it's unlikely that you’re ever going to have a single-vector situation," says Longcore. "The holy grail here is figuring out what lots of have species have in common."

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