Outdoor lighting makes it possible for humans to safely live their lives well after sunset. But the excessive use of illumination is turning skies once dark enough to see thousands of stars into a flat haze.

And the issue goes far beyond not being able to spot Orion's Belt.

"Light pollution " is a global phenomenon that disrupts ecosystems, disorients migrating creatures and disturbs humans' circadian rhythms, experts warn. “光污染”是一种全球现象，它会破坏生态系统，使迁徙生物迷失方向，扰乱人类的昼夜节律，

In efforts to kickstart mindful artificial light usage in California, dark sky advocates reintroduced legislation in December that would dim the artificial light glowing from state buildings, following a previous veto from Gov. Gavin Newsom in September.

AB 38, a repackaged bill written by Assembly member Alex Lee, D-San Jose, would put greater standards 制定更高的标准 all outdoor lighting fixtures installed or replaced on state-owned, leased or managed property.

Building owners would have three eco-friendly options to choose from - installing external shields to prevent light from shooting into the sky, setting up shutoff timers or using motion-activated lights. 建筑业主将有三种环保选择——安装外部防护罩以防止光线射向天空，设置关闭计时器或使用动作激活灯。

"Light pollution is pollution, and it has harmful impacts on our ecosystem," said Lee in a statement.

Earlier in 2022, Gov. Gavin Newsom shut down the bill despite its bipartisan support, saying it was expensive and "an overly broad mandate that raises concerns for health and safety, security, and crime prevention."

But proponents said the veto was ill-considered, citing several exemptions listed in the bill for prisons, first responder services and buildings concerned with vandalism.

Activists are bringing the bill back in hopes that this will be California's first step towards minimizing its light pollution.

If passed, California would follow the footsteps of 19 other states — including Arizona, Texas and New York — that have authorized "dark skies" legislation to some degree, whether that be for energy conservation, astronomical research purposes or human and environmental health.

How light harms

Eighty percent of all migrating bird species use the night sky as their roadway to and from their breeding grounds, said the National Audubon Society. Excess artificial light can distract the birds and draw them towards human environments, where they are more at risk of colliding with buildings and structures. 过多的人造光会分散鸟类的注意力，并将它们吸引到人类环境中，在那里它们更有可能与建筑物和结构物相撞。

In the Bay Area, the region's hazy glow can be disorienting for the millions of birds that use the Pacific Flyway, a popular travel route to seasonally migrate north and south.

This is only one of the myriad of consequences from artificial light, said Mike Lynes, policy director for Audubon California. Residents are installing more light fixtures than necessary for the sake of safety, without knowing that it can cause harm to wildlife, neighbors and themselves.

"Those of us that are concerned about the problem want to try to get a handle on it before it gets any worse," Lynes said. "A bill like this can demonstrate that your buildings can be safe, you can use a light appropriately, but turn it off when you don't need it."

For humans, being exposed to bright light after sunset can slow down melatonin production, an essential hormone for quality sleep and immune system support. 对人类来说，日落后暴露在强光下会减缓褪黑激素的产生，褪黑激素是保证睡眠质量和免疫系统支持的必要激素。

Responsible light management is situational and conditional, he said. The bill is an opportunity for the state to consider ways it can cut down on wasteful energy use, which not only saves money but also conserves biodiversity and protects the night sky.

The International Dark-Sky Association estimates that at least 30 percent of all outdoor lighting in the country is wasted, burning an extra $3.3 billion and releasing 21 million tons of carbon dioxide a year. 全国至少30%的户外照明被浪费，每年额外消耗33亿美元，释放2100万吨二氧化碳。

Cities like Los Angeles or San Francisco have historically been light pollution hubs, but as urban boundaries expand into rural areas, light is beginning to pour into previously dark areas, drawing insects — and therefore the rest of the foot chain with them — to places they should not be.

"If there's an area that we know has sensitive wildlife, that would be a place that I would flag to try to darken, if possible," Lynes said.

It's how you use light, not how much

Mindful light design can mitigate the effects of light pollution 用心的灯光设计可以减轻光污染的影响, said Lynes.

For example, take classic lamp post that is essentially just an orb of light spreading light around the sky. It's capable of reflecting light up to the clouds, wasting energy and confusing migrating birds, and shining on people's properties who may not want light spewing into their windows at night — something called light trespassing. 它能够将光线反射到云层上，浪费能量并使候鸟困惑，并照亮那些可能不希望夜间光线射入窗户的人的财产——这被称为“光侵入”

Shielding the top part of the orb can make a significant difference both in light pollution and trespassing, Lynes said. This can ensure that a place like a trailhead of a hiking trail can be lit without light spilling into the natural habitat it surrounds.

"A lot of what we're talking about is not expensive, it doesn't require any new technology. For the most part, it's a decision when the new installations are going in," Lynes said.

Opponents to light pollution mitigation efforts cite crime and safety concerns as a main reason for contention.

But environmental scientist Travis Longcore said there is a solutions-oriented approach; using LEDs to our advantage, and the basics of how the human eye works.

"I think people get afraid of this topic because they think that people won't be safe, and they're going to be plunged into darkness, and there's going to be crime everywhere," Longcore said. "And that's just not what's going on here. The Dark Sky community is very solutions-oriented, because we know and understand just how much energy and light you can save by doing good lighting as opposed to a lot of the lighting that's out there."

Longcore said that too bright of a light makes shadows darker for humans. A dimmed light that illuminates the area, rather than flooding it with light, can allow people to better see into the shadows and be more situationally aware. 用暗淡的灯光照亮这个区域，而不是用大量的光线照亮它，可以让人们更好地看到阴影，更清楚地了解情况。

"If you have a super honkin', bright, quote-unquote 'security' light that comes on, people feel safe because there's so much light," Longcore said. "But what they need to realize is that because that light is there and so bright, their eyes are adapted to that brightness, and all of the shadows are darker 但他们需要意识到的是，因为有光，而且很亮，他们的眼睛适应了这种亮度，所有的阴影都变暗了."

"You can't see shadows, they become pitch-black, and your eye is unable to adapt to that because it's got that super bright light there,"你看不到阴影，它们变得漆黑一片，你的眼睛无法适应这种情况，因为那里有超亮的光线 Longcore added.

The case for LEDs

Ever since light bulb companies began producing mass quantities for a cheap price in the mid-00s, LED lights have become the next big lighting source. Not only are they cheaper, but they save significantly more energy and cut back on people's electrical bills.

The boom even prompted the U.S. Environmental Protection Agency to pledge to phase out incandescent bulbs and switch to LEDs in 2007.

Too much of a good thing can be a bad thing, however. 然而，好事太多也可能是坏事 When LEDs became significantly cheaper to use than incandescent, people began illuminating spaces with more lights for longer, said Longcore.

But LEDs still have great potential to mitigate light pollution, because they can be dimmer, very directional and tailored to emit a warmer hue to minimize nighttime impact.

'Light pollution is pollution, and it has harmful impacts on our ecosystem.'

-Alex Lee, member, state Assembly

Earlier models of LEDs were derived from blue light, which was then coated with phosphor to produce a bright white light, said Longcore.These blue-heavy lights could easily scatter across the atmosphere because of their short wavelength and significantly contribute to the sky glow that washes out the stars. They also coincidentally attract more insects.

"Blue is the signal to basically all of life that it's daytime. So being exposed to blue light at night affects circadian rhythms, the daily physiological rhythms of humans as well as other species at sensitivities far lower than what humans are sensitive to," Longcore said.

Though LEDs have been historically criticized by the ecology community, Longcore said the industry has made improvements, like selling yellow-hued lights that are less harmful for the environment. Caltrans recently agreed to use them during construction of the world's largest wildlife crossing bridge over the 101 freeway in Los Angeles.

"They can be bad, but we can do them right and the technology is here to stay," Longcore said.

A step in the right direction

Lynes is hopeful that California can inspire change in how private homeowners, businesses and municipalities use their lights, especially as the state continues to expand.

"This is a good time for California to step in and start be a leader on the issue. This bill is a really good first step to do that," Lynes said.

Longcore said the bill appears modest in scope, but it has the potential to turn best practices from light experts into law. State agencies like Caltrans and the California Department of Fish and Wildlife have already begun researching ways to cut back on their light emissions.

"We can be much more aggressive about regulating light escaping from private properties and even from public outdoor street and area lighting. But this is just a good first step to show that the state recognizes this is a real issue," Longcore said.我们可以更积极地规范从私人财产，甚至公共室外街道和区域照明中逸出的光线。但这只是一个很好的第一步，表明国家认识到这是一个真实的问题

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