December 2017 UPDATE:
The results from the LED lighting study that was conducted in Lex-Ham and two other Saint Paul neighborhoods last winter/spring by Public Works can be viewed by clicking on the link above. The next step will be for the City to issue a request for proposals (RFP) for an LED bulb to be created that would suitable for our residential streets based on the findings of the study.
The lower Kelvin level bulbs were found to be strongly preferred and the top-mounted sample which directed the light down toward the ground made a difference in livability as well. Currently, 3000 Kelvin bulbs are not available for top mounting on our older lantern-style fixtures. The RFP process including selecting a manufacturer, creating the new bulbs, and installing them could take up to a year to compete.
In the short term, Public Works has committed to replacing the 4000 Kelvin LEDs in our neighborhood with a 3000 Kelvin LED that is corncob-shaped (the rounded one in the picture above) which was the second-most favored option from the study.
Background on LEDs in Lex-Ham
4000 Kelvin LEDs were chosen to replace the streetlight bulbs throughout Saint Paul. Lex-Ham is one of the first residential areas where they were implemented, starting on Portland Avenue in April 2016. The Lex-Ham Council office heard from several dozen neighbors with opinions or questions about the change.
One type of bulb was tested per block on the following streets between Lexington and Griggs:
The Lex-Ham neighborhood was used to test bulbs in the older lamp post style lights. Two other neighborhoods were sites for testing bulbs in the newer lamp post style lights.
Here is a summary of information on 4000K blue-rich light gathered by Lex-Ham residents: Light-Emitting Diode (“LED”)
- brighter that traditional lights
- available in a variety of color temperatures
- have a longer lifespan
- more energy efficient that earlier generation bulbs
The concerns regarding the 4000K blue-rich LED bulbs are listed below.
a. Exposure to blue-rich light at night can lead to decreased melatonin secretion in humans
- Melatonin, secreted by the pineal gland, helps balance: reproductive, thyroid, and adrenal hormones and regulates the body’s circadian rhythm of sleeping and waking
- Lower melatonin levels have been linked to increased risk of cancer
b. The AMA adopted a position on LED street lights at their annual meeting June 14, 2016, recommending that the lighting should have a color temperature of no greater than 3000 Kelvin (K). The ones installed in Lex-Ham are 4000K. Incandescent has a CT of 2400K (Color Temperature (CT) measures spectral content – a higher rating means greater blue content and whiter light appearance). Here is a summary of the AMA recommendations:
- Supports reduced energy consumption of LEDs
- Encourages minimizing and controlling blue-rich lighting by using the lowest emission of blue light possible
- Encourages the use of 3000K or lower lighting for outdoor installations such as roadways and proper shielding be installed to minimize glare and lighting be dimmed for off-peak time periods.
c. Discomfort & Glare – causes pupil constriction and can damage the retina
d. Circadian Rhythm is disrupted by blue light in humans and other lifeforms