When we consider all forms of pollution, light pollution is almost always overlooked. A starless sky is taken for granted in the city, as residents depend on bright street lights and house reflectors for their safety and convenience. However, according to a recent study by researchers from the National Oceanographic and Atmospheric Administration (NOAA), the cost of this security is much higher than starless nights.

Many air toxins released in urban environments, such as ozone, accumulate during the day and are dispersed at night through a series of chemical reactions in the atmosphere. The main reagent studied, the nitrate radical, renders many toxins harmless, but is inactivated by sunlight. Although the lights used in homes, businesses and streets are not as powerful as the sun, the study shows that the nitrate radical is significantly affected by them.

Measurements of the atmosphere over Los Angeles found that city lights were responsible for decreasing the formation of nitrate radicals by 7% and increasing the amount of ozone precursors by 5% the next day. This may not sound like much, but a lot of US cities are approaching or exceeding federal clean air guidelines already. The problem becomes more significant when we consider that those high pressure sodium and metal halide lights, the most common forms of street lighting, cause more pollution through night operation.

Light pollution also has other effects discovered in recent years. The mechanism behind a previously identified link between light pollution and an increase in breast cancer has been discovered by researchers studying the effects of melatonin. The production of melatonin in the brain occurs mainly in the dark, and melatonin was found to inactivate the effects of sex hormones in reproductive tissues. Many disorders, from prostate cancer to insomnia to PMS, are exacerbated when nighttime lighting decreases the production of melatonin.

This is not a surprise since the reproductive cycles of animals are largely determined by the changing length of night during the year. Light pollution can cause serious problems for wildlife by disrupting breeding cycles and interfering with migratory patterns. According to the Purdue researchers, light also damages many common deciduous trees and shrubs, as these plants also depend on the changing length of the night.

Policy makers, business owners and individuals need to be aware of the costs of light pollution and make the necessary adjustments. There are immediate benefits to doing so, including lower energy bills and less fossil fuel pollution. Fixing this problem is as easy as turning off the lights, but it doesn’t necessarily mean compromising safety or convenience. Traditional lights can be swapped out for dark sky lighting, led or ground led lights, with extended hood accessories, to significantly reduce glare from the sky.