Light Pollution

I once asked a Chinese-American friend if she ever misses living in China.

“No,” she said.  “I couldn’t breathe there, and I could never see the stars. I love seeing them here.  They are so beautiful.”

Her response was flattering.  It can be tempting to forget America’s environmental failures and instead congratulate ourselves on the success of certain policies.  The Clean Air Act of 1990 allows us to breathe without difficulty and enjoy the stars at night.  However, the latter benefit is increasingly threatened by a new kind of unregulated pollution: light pollution.

Light pollution, the excessive and misdirected use of nighttime lighting, is now endemic to cities, highways, and even small towns.  Witness any store at night.  Hours after closing time, fixtures flood the surrounding area with light.  The intended objects of lighting, sidewalks and parking lots, are lit as bright as day.  Meanwhile, most of the light is projected wastefully into the sky, dimming all but the brightest few stars.

Astronomers are concerned about the situation, which has worsened with the spread of urbanization.  One astronomer, John Bortle, notes that while it used to be possible to drive to sites dark enough for stargazing in the northeast, these areas have been almost completely eradicated.  Bortle developed the Bortle Dark-Sky Scale to rate darkness, ranging from 1 (regions of the Milky Way are bright enough to cast shadows) to 9 (background glow is bright enough for reading newspaper headlines).  Most typical suburbs rate 5 or 6 on the scale, making astronomy, both amateur and professional, a difficult prospect.

Consequences of light pollution are not limited to reduced visibility of the stars.  Recent research has suggested that light pollution can disrupt human circadian rhythms, and may be linked to higher incidences of breast cancer in women who work night shifts.  Humans aren’t the only ones adversely affected by the new prevalence of nighttime lighting.  Migrating birds, confused by artificial light, are killed by the thousands when they fly into buildings and guide lights.  Light pollution also disrupts the life cycle of sea turtles. Artificial lights cause newly hatched turtles to travel away from the ocean, resulting in their death when they encounter predators and roads.

Light pollution’s economic impact alone is an argument for its prevention.  The International Dark Sky Association estimates that unnecessary nighttime lighting costs the U.S. about 3 billion dollars a year.  The oil burned to produce that energy releases 21 million tons of carbon into the atmosphere–not an insignificant contribution to global warming.

Unlike many environmental problems, light pollution is both reversible and technologically easy to prevent; it does not demand significant changes in our lifestyle.  All it requires is shutting off lights that aren’t needed, such as overnight interior lighting in office buildings and redundant flood lights in parking lots.  As for outdoor lights, it isn’t necessary to eliminate them.  They simply need to use the proper fixtures.  Fully shielded fixtures point light down to the ground, preventing it from leaking above the horizontal plane into the sky.  Local ordinances can help guide businesses in the right direction when choosing outdoor light fixtures, as can public awareness.

Yet the deceptively forgiving nature of light pollution is what makes the problem urgent, especially since the greatest losses we face are the intangible ones.  Most Americans, myself included, have never seen the Milky Way.  But we don’t miss what we can’t remember.  It never seemed sad to me until I saw stunning pictures of our galaxy online.

In my own small Massachusetts hometown, a field that used to contain a barn and wildflowers was replaced by a shopping mall.  The mall uses large globe fixtures that illuminate its parking lot all night, projecting a broad, hazy dome of light into the sky.  The glow is visible from my backyard a ten-minute drive away.  I cannot remember now what the sky in my backyard looked like before the mall was built.  I know only that its quality has been diminished–and that, at the same time, younger residents of the town accept this mall as ever-present and unchangeable.

That is why it’s crucial to combat light pollution now.  Otherwise, if we accept incremental degradation in the beauty and quality of our surroundings, soon none of us will remember what things were like before.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s