Evaluating Color Temperature of LED Streetlights

In recent years, white light emitting diode (LED) lighting have emerged as a popular option for modern street lights. These LED lighting has better energy efficiency and longer lifespan than other types of lighting. Despite these benefits, the American Medical Association (AMA) expressed concerns over the use of white LED streetlights with high color temperature (CT) value.

Expressed in Kelvin (K), CT is a parameter used to express the color characteristics of light numerically. A high CT values would indicate that the light is emitting more blue content, which may be harmful to the human retina over a long period of time. The AMA recommends that the CT of street lighting should not be higher than 3000 Kelvin (K).

Measuring the CT alone is insufficient as it does not factor in human color perception. Two white LEDs with similar CT values may look different from each other where one may emit more blue content than the other. Using measurement parameters such as correlated color temperature (CCT) and spectral power distribution (SPD) provides a more comprehensive evaluation on whether the LED streetlights are emitting blue content within a safe range.