A 2021 study of Italy's COVID-19 cases also found a positive correlation with outdoor light pollution. The researchers believe light pollution may depress the human immune system to accelerate virus infection.

Although LED lights are more energy-efficient, the blue light wavelengths such street lighting emits are five times more disruptive to people's sleep cycle than conventional bulbs. The ecological disorientation causes needless deaths of migratory birds and baby sea turtles annually.

The International Dark-Sky Association (IDA) calculates excess outdoor lighting caused global annual energy waste equivalent to the output of 2.6 million tons of coal and 13.6 million barrels of oil. It estimates there is 30 percent of outdoor lighting waste in the United States alone, costing up to $3.3 billion, emitting 21 million tons of carbon dioxide per year. To offset the recurrent CO2 emissions, 875 million trees would need to be planted annually.