The Nobel Prize in physics was awarded this year for the development of LED lighting as that technology came under increasing attack for its possible deleterious effects on the night sky and possibly human and animal biology.

This week, the International Dark-Sky Association (IDA) announced restrictions on the most disruptive or bluest spectra of LED lighting in its “Fixture Seal of Approval” program.

“Exposure to blue light at night has known negative effects on ecology and is thought to cause certain kinds of chronic disease in humans,” the IDA said in releasing its new rules.

“It can increase glare, compromising human vision, especially in the aging eye. The blue component of outdoor white LED lighting also increases light pollution more than older lighting technologies,” its announcement said.

In Davis, Calif., meanwhile, the city is replacing LED lighting it installed earlier this year with lighting that would meet and actually exceed the new IDA model requirements.

Jim Benya, a lighting consultant in Davis who is also a member of the IDA’s technical committee, said Davis residents led the push for that change. The bright LED lights were causing glare and were scattering light more widely than the sodium lights they had replaced, he said.

LEDs, or light-emitting diodes are becoming ubiquitous. They are in our computer screens, handheld devices and headlights. They are increasingly used for indoor lighting as the price of bulbs and fixtures decreases and they have become a cost-and-energy-saving alternative for outdoor lighting.

Benya said the IDA is not opposed to LEDs. When the right ones are installed the right way, they achieve energy efficiency without sacrificing the quality of the light being cast, he said.

He pointed to the parking lot of Tucson International Airport as an example. It recently installed LED lights with a “correlated color temperature” of 3000K, which matches the IDA’s approved level and is well below the level of 3500K set in the Tucson/Pima County Lighting Code.

The “K” in the rating stands for the Kelvin temperature scale and refers to the correlation between heat and color. The higher the temperature, the bluer the light.

“We’re doing this because there is a concern with the pace at which LEDs are coming to market and the content of blue-rich white light,” said Matt Root, the IDA’s technical director.

“LED lighting has many great attributes,” he said.

“It is efficient in energy use and can be very directional.”

The IDA has been working toward a standard for LED lighting since 2010, when it issued a white paper on light-emitting diodes.

It concluded that blue-rich white light from LEDs caused 15 percent to 20 percent more light scattering than the high-pressure and low-pressure sodium lamps they replaced.

On the visible spectrum, blue light emits at shorter wavelengths, making it more conducive to scatter. It’s the reason why the daytime sky appears blue to the human eye.

The white paper also urged scientific study of the effects of various wavelengths on the ecology of the nocturnal world.

It warned of blue light’s disruption of circadian rhythms and melatonin secretion and a possible link to cancers.

Contact reporter Tom Beal at tbeal@tucson.com or 573-4158.