Municipal LED Lights: A Bright Idea?

The implementation of new Light Emitting Diode (LED) streetlights can be complicated, and if not well considered, may not be as bright of an idea as originally thought. With every major change in infrastructure, there are benefits and potentially harmful side effects. On the positive side, municipal LED bulbs don’t use up as much electricity, thereby saving costs on energy. Also, with longer bulb lifetimes, the LEDs will save the city maintenance and replacement costs. All together, there is an estimated cost savings of $1M annually from the PUC for our new LED street lights, with a project payback within 8 years.

Everything sounds great in terms of cost and energy savings, so why would anybody be losing sleep over this issue? That’s just it. LED bulbs emit very high-intensity light, in particular blue light, that interferes with sleep. The white-looking light actually has a high concentration of blue wavelengths. Blue light suppresses melatonin; the hormone that is produced by the body which signals when it is time to go to sleep. With repeated exposure to blue light at nighttime, our circadian rhythm gets disrupted and essentially confuses our body as to when it’s time to go to sleep. This causes lack of sleep, interruptions in duration of sleep, and increased grogginess upon waking up.

Even if you’re resting easy, the wildlife certainly isn’t. The light pollution plus the blue wavelengths are wreaking havoc on certain species of birds, insects, turtles and fish. The blinding light disorients them, and can make it hard to find prey, or get back to their habitat.

The new LED streetlights are also creating a hazard for anyone driving at night. LED light is directional – meaning it doesn’t get diffused into a pool of light. Rather, it travels in the direction that the light is pointing. This means that the gap between lights is effectively not getting lit up. The high intensity of the light also creates a much worse “glare zone” on the windshield of cars. These flashes of bright light can disorient drivers, and cause temporary blindness.

Recognizing these risks, The American Medical Association recommended:

"Recognizing the detrimental effects of poorly-designed, high-intensity LED lighting, the AMA encourages communities to minimize and control blue-rich environmental lighting by using the lowest emission of blue light possible to reduce glare. The AMA recommends an intensity threshold for optimal LED lighting that minimizes blue-rich light. The AMA also recommends all LED lighting should be properly shielded to minimize glare and detrimental human health and environmental effects, and consideration should be given to utilize the ability of LED lighting to be dimmed for off-peak time periods.

All in all, removing the old High Pressure Sodium streetlights and converting to LED is a step in the right direction. Saving on energy should be a top priority of all infrastructure endeavors. But moving forward, certain measures like dimming the lights, using proper shielding, and investigating different bulbs that emit lower levels of blue light should all be considered.