This recent article in US News gives a great, quick overview of the problems associated with over-lit nighttime skies, with a few new insights I find helpful. I want to summarize it here, by way of a brief review of many of the topics already covered on this site.
- Up to 30 percent of outdoor lighting is wasted, costing the US over $10 billion a year and adding 38 million tons of carbon dioxide to the atmosphere.
- Stargazing is increasingly difficult in brightly-lit urban centers, with the best viewing conditions usually experienced in the countryside. Estimates put visible stars at 2,000 in dark, rural areas, with on three visible in bright city squares.
- Nightshift work and bright cities are being linked to higher cancer rates. Some studies indicate that women who work at night are 70 percent more likely to develop breast cancer than their non-nightshift working counterparts. Prostate cancer rates may also be higher in men who work at night. Boosts in cancer rates are likely due to the disruption in circadian rhythms and lower production rates of melatonin.
- Bright lights negatively affect wildlife in a number of ways. Illumination from cities has been recorded as traveling up to 200 miles into national parks. This light can disorient wildlife, taking them away from their normal migratory paths and disrupting their mating and feeding habits.
- Rather than making situations safer, light can actually contribute to increases in crime and accidents. Glare from lights that shine directly in a person’s eye can cause momentary blindness, disorienting pedestrians and drivers alike. And high-contrast illumination created by overly-lit areas can create pockets of shadow where criminals can hide.
All of these reasons make it plain that we need a lighting revolution. All of the problems together – from the environment to finances, human health to human safety – make for a more than compelling case for increased dark sky ordinances nationwide. Light pollution is a serious problem but there are solutions all of us can put into place to begin to change this.