Built Environment

Health Effects of LED Street Lights

Toronto Public Health Briefing Note: Health Effects of LED Street LIghting


On September 27, 2016 the Public Works and Infrastructure Committee requested the General Manager, Transportation Services to report to the Public Works and Infrastructure Committee, in consultation with Toronto Hydro, Toronto Public Health, and the Environment and Energy Division on possible benefits and risks to the public associated with the prevalent use of LED or other similar street lighting technologies in the Toronto street lighting system, and such report to include, but not be limited to:

a. consideration of the human health effects related to light colour temperature and intensity;

b. down lighting directional capabilities and light pollution effects;

c. contrast and traffic safety risks or benefits;

d. crime prevention factors; and

e. aesthetics.[i]


  1. The City of Toronto to install LED streetlights with a colour temperature rating of 3000K or less with options for dimming lights during non-peak times and shielding to reduce glare
  2. Toronto Public Health to monitor the research related to the impacts of LED lighting on     health.



In the last decade, cities have been looking for ways to reduce their energy consumption and reduce operating costs of street lighting.  One way to do this has been to replace the existing high pressure sodium (HPS) street lighting with more energy efficient light emitting diode (LED) street lights.

LED lighting has become the preferred choice by municipalities due to better colour rendering, more uniform lighting distribution, increased energy savings, increased reliability, dimmable configurations and decreased maintenance costs over traditional high pressure sodium lighting[ii].

The visual spectrum of light is defined as wavelengths from 360nm to 700nm, with blue light found in the 400-500nm range[iii].  Most HPS lights emit the majority of their energy between 550-650nm (yellow/orange spectrum); on the other hand, white LED lighting has a higher proportion of energy with wavelength under 500nm3 (blue spectrum).

Toronto hydro has completed a pilot of LED street lights at 6 sites across the city.  A survey of residents found that the majority were satisfied with the brightness of street lights and supported a city-wide roll out.  About 20 percent of respondents indicated that the lights were too bright.


Health Evidence Summary:

The main health impact of exposure to light is related to its effect on maintenance of the circadian rhythm. Studies indicate that disruption of our circadian system is associated with an increased incidence of diabetes, obesity, heart disease, cognitive and affective impairment, premature aging and some types of cancer[iv].

Not all wavelengths of light disrupt our circadian systems at the same level. Short wavelength blue light, which is known to help with alertness in the daytime, seems to be more disruptive at night, and induces the strongest melatonin inhibition[iv].  Melatonin is an important antioxidant with a significant role in antioxidant defense, regulating enzyme activity and production[v].

LED lighting in the blue spectrum has been shown to be stronger at suppressing melatonin than equivalent 4000K fluorescent lighting[vi]. The proliferation of energy-efficient lighting (LEDs) and electronic devices are increasing our exposures to blue light during the night[vi].

Studies suggest that artificial light at night (ALAN), including dim light, has adverse effects on sleep quality[vii].  A significant association between outdoor ALAN exposure and obesity which cannot be explained by potential confounding factors has been found[viii], [ix].  Other observation studies suggest that outdoor ALAN levels are a risk factor for breast cancer[x].

Glare, from too much bright light, can dazzle, mask hazards and can cause temporary vision loss increasing the risks of trips, falls or safety threats[xi].  Dark adaptation; the eye's ability to adjust to reduced lighting levels is important for safety in the community.  The time it takes for the eye to adapt from the lit areas and the unlit areas increases with the brightness and colour of lighting[xii].  Research indicates that LED lights less than 3000K have better dark adaptation times than cooler 4000K or 5000K LED lights[xii].  The design of LED lights can have an impact on the amount of glare it produces, appropriate shielding and diffusing and directionality of the lighting can reduce risks associated with glare[xi].  

Jurisdictional Review:

The American Medical Association[xiii] recently released a position statement recommending communities that are converting street lighting to LED use lower correlated colour temperature (CCT) lights to minimize potential health and environmental effects.  Its recommendations included proper conversion to LED lighting, to reduce fossil fuel and energy consumption; minimizing and controlling blue light emission to reduce glare and using 3000K or lower (CCT) for outdoor installations, including shielding to minimize glare and dimmable lighting for off-peak time periods.

Many cities across Canada, in the United States and throughout Europe have converted or are going through the process of converting their street lighting systems to LED lighting.  The majority of these cities are installing 4000K LED lights.  A number of these cities have had a large number of complaints on the harshness of the lights and increased glare[xiv],[xv].  As a result a few cities have replaced the newly installed LED lights with lower correlated colour temperature ones[xvi][xvii].  Since the AMA’s recommendation was released a number of cities are suspending the replacement of streetlights pending further review[xviii], including Surrey, BC[xix] and Montreal, QC[xx].

Ottawa is using LED that are a similar temperature to the existing high pressure sodium lighting (3000K) in residential neighbourhoods[xxi].  Other cities including Kitchener[xxii] are converting to 3000K LED lighting and Lake Worth, Florida[xxiii] are converting to 2700K LED lighting.  Research in to the performance of different CCT LED street lights indicates that low colour temperature (approximately 3000K) are more suitable for street lighting[xii].

Health units in Canada are starting to look in to the issue.  The Region of Waterloo Public Health and Emergency Services division recently made the recommendation of 3000K or lower LED lights that are shielded and dimmed at off peak hours for street lighting[xxiv]

Prepared by: Kelly Drew, Healthy Public Policy

Circulated to: Ashley Curtis, Acting General Manager Transportation Services

Further information: Kelly Drew, Healthy Public Policy, Kelly.drew@toronto.ca

Date: October 3, 2016;  Revised January 24, 2017


[i]Public Works and Infrastructure Committee September 27, 2016 http://app.toronto.ca/tmmis/viewAgendaItemHistory.do?item=2016.PW15.7  Accessed September 27, 2016

[ii] LED Streetlights in your Neighbourhood, Toronto Hydro http://www.torontohydro.com/sites/electricsystem/GridInvestment/powerup/Pages/LEDStreetlights.aspx  Accessed Sept 29, 2016

[iii] International Dark-Sky Association.  Visibility, Environmental and Astronomical Issues Associated with Blue-Rich White Outdoor lighting.  May 4, 2014.  www.darksky.org/wp-content/.../bsk.../8_IDA-BLUE-RICH-LIGHT-WHITE-PAPER.PDF Accessed September 30, 2016

[iv] Bonmati-Carrion MA, Arguelles-Prieto R, Martinez-Madrid MJ, Reiter R, Hardeland R, Rol MA, Madrid JA.  Protecting the Melatonin Rhythm through Circadian Healthy Light Exposure. Int J Mol Sci. 2014 Dec 17;15(12):23 448-500

[v] Navara K.J., Nelson, R.J.  The dark side of light at night: Physiological, epidemiological, and ecological consequences.  J. pineal.Res. 2007; 43:215-224

[vi] West KE1, Jablonski MR, Warfield B, Cecil KS, James M, Ayers MA, Maida J, Bowen C, Sliney DH, Rollag MD, Hanifin JP, Brainard GC. Blue light from light-emitting diodes elicits a dose-dependent suppression of melatonin in humans.  J Appl Physiol (1985). 2011 Mar;110(3):619-26

[vii] Cho C, Lee H, Yoon H, Kang S, Son S, Bok K, Jung K, Kim L, Lee E; Exposure to dim light at night increases REM sleep and awakenings.  Sleep 2014; 37, A298 (A298-A299) Proceeding held: CONFERENCE START: 2014 May 31 CONFERENCE END: 2014 Jun 4 in 28th Annual Meeting of the Associated Professional Sleep Societies, LLC, SLEEP 2014 Minneapolis, MN United States

[viii] Koo YS, Song JY, Joo EY, Lee HJ, Lee E, Lee SK, Jung KY.;  Outdoor artificial light at night, obesity, and sleep health: Cross-sectional analysis in the KoGES study. Chronobiology International: The Journal of Biological & Medical Rhythm Research. 2016;33(3):301-314.

[ix] McFadden, E., Jones, M.E., Schoemaker, M. J., Ashworth, A., Swerdlow, A.J.; The Relationship Between Obesity and Exposure to Light at Night: Cross-Sectional Analyses of Over 100,000 Women in the Breakthrough Generations Study. American Journal of Epidemiology. 2014; 180(3):245-250.

[x] Cho, Y.M., Ryu, S., Lee, B.R., Kim, K.H., Lee, E., Choi, J.; Effects of artificial light at night on human health: A literature review of observational and experimental studies applied to exposure assessment. Chronobiology International: The Journal of Biological & Medical Rhythm Research. 2015;32(9):1294-1310

[xi] Ticleanu, C., Littlefair, P.  A Summary of LED lighting impacts on Health. International Journal of Sustainable Lighting.2015;1:5-11

[xii] Jin H, Jin S, Chen L, Cen S, Yuan K. Research on the lighting performance of LED street lights with different color temperatures. IEEE Photonics Journal. 2015;24(6):975-78. http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7328247. Accessed September 14, 2016.

[xiii] AMA Adopts Community Guidance to Reduce the Harmful Human and Environmental Effects of High Intensity Street Lighting.  June 14, 2016 http://www.ama-assn.org/ama/pub/news/news/2016/2016-06-14-community-guidance-street-lighting.page  Accessed September 26, 2016.

[xiv] Chaban M. LED streetlights in Brooklyn are saving energy but exhausting residents. NY Times; March 23, 2015. http://www.nytimes.com/2015/03/24/nyregion/new-led-streetlights-shine-too-brightly-for-some-in-brooklyn.html?_r=0  Accessed September 26, 2016.

[xv] Scigliano E. Seattle’s new LED-lit streets Blinded by the lights. Crosscut. March 18, 2013. http://crosscut.com/2013/03/streetlights-seattle-led/ Accessed September 26, 2016.

[xvi] Davis Will Spend $350,000 To Replace LED Lights After Neighbor Complaints.  October 21, 2014 http://sacramento.cbslocal.com/2014/10/21/davis-will-spend-350000-to-replace-led-lights-after-neighbor-complaints/  Accessed September 26, 2016

[xvii] City replacing some LED street lights because they're too bright.  May 14, 2016. http://nypost.com/2016/05/14/city-replacing-some-led-street-lights-because-theyre-too-bright/ Accessed Sept 26, 2016.

[xix] Surrey reviewing lighting plans in wake of warning over health effects of LED lights. September 28, 2016 http://globalnews.ca/news/2967725/surrey-reviewing-lighting-plans-in-wake-of-warning-over-health-effects-of-led-lights/  Accessed September 28, 2016

[xx]  Opposition calls for suspension of Montreal's LED streetlights project April 18, 2016 http://montrealgazette.com/news/local-news/opposition-calls-for-suspension-of-montreals-led-streetlights-project  Accessed September 26, 2016

[xxi] LED Streetlight Conversion Project http://ottawa.ca/en/residents/water-and-environment/green-living/led-streetlight-conversion-project .  Accessed September 27, 2016

[xxii] Recommendation: That Light Emitting Diode (LED) street light replacement program. March 7, 2016 https://www.kitchener.ca/en/Calendar/Download.ashx?Id=ae03f3fe-138e-4f9f-b1fe-a62ed56c24aa Accessed September 27, 2016

[xxiii] Street Lighting with A New Approach http://www.lakeworth.org/topics/2016/05/03/lightsapproach/ Accessed September 27, 2016

[xxiv] Region of Waterloo Public Health and Emergency Services, July 28, 2016, Briefing Note: LED (Light Emitting Diode) lights and health effects.