光污染的危害到底有多大？适度照明如何做？

【中国绿发会讯】随着经济的快速发展，光污染问题日益凸显，已成为全球不可忽视的污染之一。人工照明不仅对人类自身健康造成严重危害，更对生物多样性和生态系统产生深远影响。

（来源：NASA）

https://earthobservatory.nasa.gov/images/90008/night-light-maps-open-up-new-applications

光污染会直接干扰自然光-暗循环，破坏生物体的昼夜节律光夹带[1]，造成生物钟紊乱，导致相关疾病正在且不断威胁人类健康[2]。全世界超过80%的人口受到不同形式的光污染的影响[3]。光污染对人类健康的潜在影响不仅会造成睡眠障碍[4]，还会引起更多疾病，如肥胖[5]~[7]、代谢紊乱[8]、精神障碍[9][10]，甚至癌症[11]~[14]等。其中，值得注意的是，涉及癌症的几个关键过程都受昼夜节律的控制[15]。可见，昼夜节律与人类的身体健康状况息息相关。另外，有研究表明，户外人造光源中的蓝光光谱暴露与结直肠癌[16]、前列腺癌和乳腺癌[17]密切相关，而可见光光谱不太会增加乳腺癌风险，且与前列腺癌呈负相关[17]。

人工照明不仅威胁着人类的健康，还破坏了野生动物的栖息地，更对其生命阶段和关键行为活动产生不利影响。有研究表明，人工光源会影响海龟筑巢[18]，改变母龟产卵行为，并会导致刚孵化的小海龟迷失方向，从而无法顺利返回大海[19]~[21]。昆虫学家认为，人工光源是昆虫减少的驱动因素[22][23]。白炽灯泡产生的中等光照水平（8-40勒克斯）会显著减少了白蚁产卵的数量[24]。人工光照还会破坏蛾的繁殖、幼虫发育和蛹滞育[25]。同样，光污染也会扰乱植物的昼夜节律，影响其发芽、开花、休眠、落叶等生长过程，进而影响到整个生态系统的平衡[26]。植物物种对人工光污染更敏感，当人工照明越亮时，物候进展受到的阻碍越明显，甚至出现延迟现象，如出叶和开花的物候期显著延迟[27]。

另外，夜晚不必要的照明会造成能源浪费，排放更多的二氧化碳，给生态环境造成更大压力。据国际暗夜组织估算，美国每年至少有30%的户外照明被浪费，大部分是没有屏蔽的灯，造成每年2100万t二氧化碳(CO2)的排放量。要抵消这部分的二氧化碳，则需要每年种植8.75亿棵树[28]。而夜间照明释放的热量也会加剧了城市“热岛效应”[29]。

随着城市化进程的加速，智慧城市的持续推进，光污染不断加剧。因此，我们需要加强治理光污染、守护好黑暗夜空。那么，在生活中，我们如何减少光污染呢？

首先，关闭不必要的照明，缩短户外照明时间。根据最近的流行病学研究，不仅辐射强度，而且光污染的光谱和时间，都是影响健康的潜在因素[30]。户外照明会影响夜行动物的行动，比如觅食和迁徙等。

其次，尽量使用暖色光的灯，远离蓝光，健康用眼。LED灯由于其节能性而被广泛用来替代传统的窄光谱照明，如钠灯（发出暖色光）。但LED灯通常会发出冷色光，而蓝光已经被证明可以降低人类褪黑激素的水平[31]。另外，电脑、iPad、手机和荧光棒等产品也存在蓝光。有研究表明，在常规电脑屏幕亮度蓝光暴露下，2h即可出现角膜上皮辐射损伤[32]。

再次，建议使用带有屏蔽罩的户外照明灯具。不必要的人工照明产生的眩光是一个日益严重的问题[33]。屏蔽罩可以防止光线超过一定范围，尽量减少眩光以及对人类和环境的有害影响。

最后，在夜晚行车不要滥用远光灯。过于明亮的照明环境会对司机的视觉造成不良影响，引起视觉疲劳，容易引发交通事故[34]。

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