Sierra Club DC Chapter
Comments on DDOT's Proposed Contract
for LED street lights
February 3, 2022
The District Department of Transportation (DDOT) has submitted to the D.C. Council a proposed contract to convert all the District's street lights to energy-efficient LEDs.
With more than 3,000 dues-paying members, the Sierra Club D.C. Chapter has an active interest in energy efficiency, along with environmental and public health. We strongly support the LED conversion project for its potential to reduce energy usage.
However, three elements of the proposed contract must be revised to take full advantage of LEDs and reduce their potentially harmful impacts on human health and the environment: 1) the amount of LED light, 2) its blue-rich color, and 3) the direction it shines.
A failure to include these revisions would lock the District into years of avoidable negative human health and environmental impacts. Sierra Club strongly urges the Council to ensure that the new LEDs meet these certain criteria so as to protect the health and well being of the people and wildlife of DC.
I. Excessive Amounts of Light
The amount of light emitted by streetlights is critical because brightness directly impacts energy usage and the urban environment.
Research has shown that artificial light at night disrupts our circadian rhythms1, alters wildlife behavior2, and causes urban skyglow that obscures the stars and disorients migrating birds3. The science therefore suggests that nighttime light is a pollutant that should be used sparingly – only what is truly necessary.
Recent epidemiological studies have found outdoor light at night – especially the blue-wavelength emissions of LEDs – associated with harmful impacts on human health, including breast cancer4, prostate cancer5, colorectal cancer6, diffuse large B-cell lymphoma7, and anxiety disorders in adolescents8. While such associations do not prove causation, these studies deserve serious consideration when designing a street-lighting system.
DDOT's stated goal for the proposed contract is replicating current light levels. This is troubling because many D.C. streets are excessively lit – far beyond what is sufficient for traffic safety according to national standards.
While the superior directionality of LEDs will reduce overall light levels somewhat, DDOT estimates that many streets, including local residential streets, would have more than twice the minimum amount of light recommended by the American Association of State Highway and Transportation Officials (AASHTO), and some arterial streets would have nearly three times as much.
Professional lighting designers have warned that excessive light is counterproductive to good visibility. Light levels "should not significantly exceed the recommended values without justification," according to the Illuminating Engineering Society of North America (IES), which sets roadway lighting standards that correspond to those of AASHTO. "More light is not always correlated with better visibility, as inappropriately designed lighting can increase visibility-reducing factors such as glare and can increase obtrusive light."9
DDOT states that LED fixtures could be dimmed at the request of neighborhood residents. This implies, however, that all the District's streets would be overlit initially. Instead, to avoid environmentally harmful excessive light, the default standard should be the minimum light levels recommended by AASHTO or IES, and no more.
D.C. residents rely on street lighting for personal safety, and some streets undoubtedly need more light. Adhering to the minimums of national standards would correct many instances of inadequate lighting. If residents of a street or block want additional light beyond the recommended minimums, they could be afforded a formal process for making their request to DDOT through their Advisory Neighborhood Commission.
II. Excessive Blue-Wavelength Light
Compared to older lights, LEDs emit greater amounts of blue light, the most biologically active component of white light.10 Blue light also produces more glare that impairs driver vision, especially for older people11, and exacerbates skyglow12.
The American Medical Association recommends that street lights have a color temperature of 3000 Kelvin or lower. (The lower the Kelvin rating, the less blue light.) The AMA also calls for "the lowest emission of blue light possible to reduce glare."13
Installing warm-white 2700-Kelvin LEDs helps mitigate skyglow and potential harm to human health. It also reduces glare, improving driver vision and making it easier for pedestrians to assess the safety of their surroundings.
DDOT's proposed contract does call for 2700-Kelvin LEDs on residential streets, but also 3000-Kelvin fixtures, emitting more blue light, on many arterial streets.
DDOT asserts that 2700-Kelvin LEDs are a safety risk on high-speed streets unless their brightness is increased. One has to question, however, whether the problem isn't 2700 Kelvin but rather DDOT's stated goal of exceeding recommended minimum light levels.
Installing 3000-Kelvin LED fixtures instead of 2700 Kelvin or lower flouts the D.C. Council's clearly stated preference for goods and services that are "less harmful to human health and the environment when compared with competing goods or services that serve the same purpose."14
The experience of other jurisdictions demonstrates that DDOT can light all the District's streets to national standards with 2700-Kelvin LEDs. Phoenix has successfully installed 2700 Kelvin city-wide, regardless of street category or surrounding land usage. Los Angeles County plans to install 2700 Kelvin for all the streetlights it owns and is investigating the option of 2200 Kelvin. DDOT should follow these examples.
III. Light Directed Upward into the Sky
Under DDOT's proposed contract, anachronistic Washington Globe and teardrop fixtures would be retained and shine some of their light directly into the sky, wasting energy and exacerbating skyglow.
DDOT's reluctance to eliminate uplight from the Washington Globe fixtures apparently responds to a request from the U.S. Commission of Fine Arts (CFA), which prefers that the entire globe surface be illuminated at night for aesthetic reasons. The commission's legislative mandate, however, primarily addresses building permits and monuments; it says nothing about streetlights15. DDOT should not allow the CFA to dictate lighting specifications throughout the District.
The proposed contract's specifications for Washington Globe and teardrop fixtures are not consistent with the D.C. Council's preference for "green" procurement and should be revised to eliminate uplight and reduce glare.
Conclusion
Thank you for the opportunity to comment on DDOT's proposed LED streetlight contract. Sierra Club believes our suggested contract revisions are consistent with the D.C. Sustainability Plan and will help make the District a national model for safe, healthy, environmentally sustainable street lighting. We further note that these revisions would better align this contract with the District’s procurement guidelines and would result in reduced harm to human health and the environment.
The Sierra Club strongly urges the Council to ensure these revisions to address excessive light, light color temperature, and uplight are included in a final contract.
1 American Medical Association Council on Science and Public Health, Light Pollution: Adverse Health Effects of Nighttime Lighting, CSAPH Rep. 4,A-12 (2012)
2 Falcon J. et al., Exposure to Artificial Light at Night and the Consequences for Flora, Fauna, and Ecosystems, Front. Neurosci., Nov. 16, 2020 https://doi.org/10.3389/fnins.2020.602796
3 McLaren, J. D. et al., Artificial light at night confounds broad-scale habitat use by migrating birds, Ecology Letters, Jan. 9, 2018 https://doi.org/10.1111/ele.12902
4 Garcia-Saenz et al., Evaluating the association between artificial light-at-night exposure and breast and prostate cancer risk in Spain (MCC-Spain Study), Environmental Health Perspectives, 2018; 126 (04) DOI: 10.1289/EHP1837
5 Ibid.
6 Garcia-Saenz et al., Association between outdoor light-at-night exposure and colorectal cancer in Spain, Epidemiology, 2020 Sep; 31(5):718-727 DOI: 10.1097/EDE.0000000000001226.
7 Zhong C. et al., Outdoor artificial light at night and risk of non-Hodgkin lymphoma among women in the California Teachers Study cohort, Cancer Epidemiology, 2020 Dec; 69:101811. DOI: 10.1016/j.canep.2020.101811. Epub 2020 Sep 28.
8 Paksarian D. et al, Association of outdoor artificial light at night with mental disorders and sleep patterns among US adolescents, JAMA Psychiatry, 2020 Jul 8; 77(12):1266-1275. DOI: 10.1001/jamapsychiatry.2020.1935.
9 Illuminating Engineering Society of North America, Recommended Practice for Design and Maintenance of Roadway and Parking Facility Lighting, §1.3.3 (2018)
10 American Medical Association Council on Science and Public Health, Human and Environmental Effects of Light Emitting Diode (LED) Community Lighting, CSAPH Report 2-A-16 (2016)
11 Ibid.
12 Luginbuhl, C.B. et al., The impact of light source spectral power distribution on sky glow, Journal of Quantitative Spectroscopy and Radiative Transfer, 139:21-26 (May 2014) DOI: 10.1016/j.jqsrt.2013.12.004
13 American Medical Association Council on Science and Public Health, Human and Environmental Effects of Light Emitting Diode (LED) Community Lighting, CSAPH Report 2-A-16 (2016)
14 D.C. Code §2-361.01 Green procurement.
15 40 U.S.C. §8104, 40 U.S.C. §§8901-8909, 40 U.S.C. §§9101-9104