對抗光污染，請把黑夜還給我！

Last July， France—including the City of Light—grew darker late at night as one of the world’s most comprehensive lighting 1）ordinances went into effect. From 1 a.m. to 7 a.m.， shop lights are being turned off， and lights inside office buildings must be 2）extinguished within an hour of workers leaving the premises.

Until recently， efforts to restrain our use of light have been primarily in response to the 3）astronomical light pollution erasing starry nights. But researchers are increasingly focusing on the impacts of so-called 4）ecological light pollution， warning that disrupting these natural patterns of light and dark， and thus the structures and functions of 5）ecosystems， is having profound impacts.

The problem is worsening as China， India， Brazil， and numerous other countries are becoming increasingly affluent and urbanized. Satellite views of the Earth at night show vast areas of North America， Europe， the Middle East， and Asia glowing white， with only the world’s remotest regions—Siberia， the Tibetan 6）plateau， the Sahara Desert， the Amazon， and the Australian outback—still cloaked in darkness.

Technological advances such as LEDs， or light-emitting 7）diodes， can improve our ability to reduce and better regulate lighting， but these same new lights may actually make things worse because they contain heavy doses of a “bluerich” white light that is especially disruptive to 8）circadian rhythms.

Some 30 percent of 9）vertebrates and more than 60 percent of invertebrates are 10）nocturnal， and many of the rest are 11）crepuscular—active at dawn and dusk. All are potentially impacted by our 12）burgeoning use of artificial light， scientists say.

Every flip of a light switch contributes to altering ancient patterns of mating， migration， feeding， and 13）pollination， with no time for species to adapt. On the Caribbean island of 14）Tobago， a 2012 study of 15）leatherback turtles—a species that has roamed the Earth for 150 million years—found that “artificial lighting of the nesting beaches is the biggest threat to survival of 16）hatchlings and a major factor in declining leatherback turtle populations.”

Many migrating birds， drawn off-course by artificial light， join the breathtaking number—between 100 million and 1 billion—killed each year by 17）collisions with human-made structures. For moths， which help pollinate the world’s flora， our outdoor lights are irresistible flames， killing countless moths and other insects， with ripple effects throughout the food chain.

Of course， “humans are animals as well，”explains Steven Lockley of Harvard Medical School’s Division of Sleep Medicine， “and so when light/dark cycles mess up seasonal patterns of trees or breeding cycles of 18）amphibians， there’s no reason to think it’s not doing the same to us.”

As recently as 1980， humans were thought to be immune to the effects of artificial light at night. But continuing research has shown that nocturnal light disrupts our sleep， confuses our circadian rhythms—those 24-hour biological processes that regulate our body’s functions—and impedes the production of the hormone 19）melatonin at much lower levels than previously thought possible.

More and more of the light we see at night—whether it’s from electronic gadgets or outdoor lighting—is rich with the blue wavelengths most disruptive to our body’s rhythms. （More than any other wavelength， blue wavelength light tells our brain that night is over， that morning’s blue sky has returned， and that the day has begun—the opposite signal that we want to be sending our brain in the middle of the night.） Studies continue to suggest that the consequences of excessive exposure to light at night include an increased risk for obesity， diabetes， and 20）cardiovascular disease.

Last year， the American Medical Association issued a statement calling for increased research into the “risks and benefits of occupational and environmental exposure to light-at-night，” and recommending “new lighting technologies at home and at work that minimize circadian disruption.”

In fact， researchers are concerned about the impact of some new lighting technologies. While their capacity to be computer-controlled and directed could make LEDs a key tool in reducing light pollution， these lights may actually make things significantly worse. Touted as energy-efficient and clearer in color， most LEDs currently being installed are often brighter than the old lights they are replacing， further increasing light pollution. In fact， as explained in a recent article from the Journal of Environmental Management， LEDs could “21）exacerbate known and possible unknown effects of light pollution on human health （and the） environment” by more than five times.

In the Journal of Applied Ecology， researchers have identified numerous practical steps to reduce light pollution： changing the 22）spectral 23）composition of lighting （especially LEDs）， limiting the duration of lighting， reducing the “24）trespass” of lighting into areas not intended to be lit， altering the intensity of lighting， and preventing areas from being artificially lit in the first place.

The relatively simple act of shielding our lights—installing or 25）retrofitting lamp fixtures that direct light downward to its intended target—represents our best chance to control light pollution.

Experts say it is far more important to use light effectively than abundantly. Explaining France’s new lighting rules， Delphine Batho， until recently France’s environment minister， described the government’s desire to “change the culture” to include the responsible use of light. This change is to be applauded， for what increasing numbers of studies—as well as our own eyes—tell us is that we are using far more light than we need， and at 26）tremendous cost.

去年七月，自世界上最全面的照明條例實施以來，整個法國，包括“光之城”巴黎，在深夜都變得相對黯然了。從凌晨一點(diǎn)到七點(diǎn)，商店的燈都必須關(guān)閉，寫字樓內(nèi)的燈必須在員工離開后的一小時內(nèi)熄滅。

直到最近，對照明使用的限制措施主要都是為了應(yīng)對天文光污染令星空日漸消失的問題。但是研究人員越來越關(guān)注所謂的生態(tài)光污染的影響，警告說對這些光與暗的自然模式的干擾會引發(fā)生態(tài)系統(tǒng)在結(jié)構(gòu)和功能上的紊亂，繼而產(chǎn)生深遠(yuǎn)的影響。

由于中國、印度、巴西和眾多其他的國家日益富裕和城市化，這個問題也日漸嚴(yán)重。夜晚的地球衛(wèi)星視圖顯示，北美、歐洲、中東和亞洲大部分地區(qū)光如白晝，只有世界上最偏遠(yuǎn)的地區(qū)——西伯利亞、青藏高原、撒哈拉沙漠、亞馬遜地區(qū)、澳大利亞內(nèi)陸地區(qū)——仍然隱匿在黑暗之中。

技術(shù)進(jìn)步的成果，諸如LED燈，即發(fā)光二極管，能令我們減少使用照明，提高對照明的掌控，但是這些新型光源實際上可能使情況變得更糟，因為它們含有大劑量的“富含藍(lán)色波長”白光，對于晝夜節(jié)律尤其具有破壞性。

大約有30%的脊椎動物和60%以上的無脊椎動物都在夜間活動，還有許多動物會在黎明或者黃昏時活動。科學(xué)家說，所有這些動物的行為都可能會因人造光源的濫用而受到影響。

每一盞燈的開關(guān)都瞬間改變著生物交配、遷移、進(jìn)食和授粉的古老模式，沒有時間讓物種自然適應(yīng)。在加勒比海島上的多巴哥，2012年的一項關(guān)于棱皮龜?shù)难芯俊馄斒且粋€在地球上生存了1.5億年的物種——發(fā)現(xiàn)“其筑巢海灘上出現(xiàn)的人工照明是孵化幼崽存活的最大威脅，也是棱皮龜數(shù)量減少的最主要因素?！?/p>

許多候鳥，因為人造光而偏離航向，數(shù)目已經(jīng)達(dá)到了驚人的程度——在1億和10億之間——每年因撞向人造建筑而死亡。飛蛾有助于世界上的植物授粉，而戶外燈光對于它們，是無法抗拒的火焰，其造成了無數(shù)飛蛾和其他昆蟲的死亡，引起了整個食物鏈的漣漪效應(yīng)。

當(dāng)然，“人類也是動物，”來自哈佛醫(yī)學(xué)院睡眠醫(yī)學(xué)部門的史蒂文·勞克雷解釋道，“光/暗周期能擾亂樹木的季節(jié)生長模式或是兩棲動物的繁殖周期，我們沒理由認(rèn)為它不會對人類也造成同樣的影響?！?/p>

直到1980年，人類還自認(rèn)為晚上的人造光不會對自己有什么不良影響。但是持續(xù)的研究表明夜間燈光擾亂我們的睡眠，使晝夜節(jié)律變得混亂——24小時的生物進(jìn)程調(diào)節(jié)著我們身體的功能——阻礙了荷爾蒙褪黑激素的產(chǎn)生，使荷爾蒙褪黑激素水平比以往預(yù)料的要低得多。

越來越多的夜間燈光——無論是來自于電子儀器或者是戶外照明——富含藍(lán)色波長，這種波長對我們的身體最具破壞性。（不像其他波長，藍(lán)色波長告訴大腦夜晚結(jié)束，早上的藍(lán)天出現(xiàn)，白晝開始了——和深夜我們想發(fā)送給大腦的信號是相反的。）研究持續(xù)表明，過度暴露于夜晚燈光之下，會增加患肥胖癥、糖尿病和心血管疾病的機(jī)率。

去年，美國醫(yī)學(xué)協(xié)會發(fā)表聲明，呼吁增加對于“在職業(yè)和環(huán)境中，暴露在夜間燈下的威脅和益處”的研究，以及倡導(dǎo)“在家庭和工作中，利用新照明技術(shù)將晝夜節(jié)律的擾亂降到最低?！?/p>

事實上，研究人員擔(dān)心的是一些新照明技術(shù)的影響。雖然，計算機(jī)的控制和定向會使LED燈成為減少光污染的重要工具，但是這些燈實際上反倒會使情況大為惡化。雖然夸口其具有節(jié)能和明晰的特點(diǎn)，但是大多數(shù)當(dāng)前使用的LED燈比其取代的舊燈更加光亮，從而增加了光污染。事實上，正如最近一篇來自《環(huán)境管理期刊》的報道所述，LED燈會以五倍多的速度“加劇已知和未知的光污染對于人類健康和環(huán)境的影響”。

在《應(yīng)用生態(tài)學(xué)期刊》上，研究人員已經(jīng)發(fā)現(xiàn)許多減少光污染切實可行的措施：改變光源的光譜組成（特別是LED燈），限制照明時長，減少光對于無需照明地區(qū)的“侵入”，改變光的強(qiáng)度，以及將防止多個地區(qū)被人造光照亮放在第一位。

屏蔽光的相對簡單的行為——安裝或者改裝燈具裝置使光線向下聚焦到預(yù)定目標(biāo)上——就是控制光污染最好的途徑。

專家們認(rèn)為，用光貴乎“效”而非“量”。最近離任的法國環(huán)境部長黛爾菲娜·巴多在提到法國的新照明規(guī)定時指出，政府希望“改變文化”，將“更負(fù)責(zé)任地使用照明”融入到新的文化意識中。這種改變值得贊賞，因為越來越多的研究，以及我們的眼睛，告訴我們，我們所使用的光遠(yuǎn)超我們所需，同時耗資巨大。