by Barbara Clowers
We promote responsible lighting design based on the principles of balancing the need for light at night with human health, environmental health, and preservation of nature, including the night sky. Elements of responsible lighting design include:
- eliminating waste which includes saving energy and reducing greenhouse gases
- capping total lumens to control light pollution,
- employing fully shielded luminaires in most applications,
- mitigating or eliminating glare,
- using lighting only where it is needed,
- choosing the proper color temperature and spectrum of light,
- eliminating over lighting,
- dimming or shutting off lights when not in use
- establish a verification and accountability process using suitable metrics
- produce an attractive outcome.
Problem: Health Risks of Blue-Rich White Light (BRWL)
- Exposure to blue-rich white light (BRWL) resets our circadian clock in the morning making us alert. The circadian clock is reset again at night by an absence of BRWL stimulating the production of melatonin and fatigue resulting in sleep. Exposure to BRWL at night disrupts circadian systems in humans and all other living beings with detrimental impacts.
- Exposure to BRWL inhibits the production of melatonin. Reduced melatonin production has been scientifically linked to human breast cancer, metabolic syndrome, diabetes and other diseases.
- In 2012 the AMA stated nighttime light exposure is hazardous human health and has potential tumor-enhancing effects related to melatonin suppression, especially for breast cancers.
Violation of Davis Dark Sky Ordinance 1966
The new LED street lights violate City of Davis Dark Sky Ordinance 1966, passed unanimously in 1998, creating standards for outdoor lighting which mitigate light trespass, reduce pedestrian glare and limit light trespass. That ordinance was passed to:
- Minimize light pollution, glare, light trespass caused by inappropriate or misaligned light fixtures and preserve the night sky as a natural resource and people’s enjoyment of looking at the stars.
- Restrict any light dispersion above the horizontal plane from the lowest light emitting point of the light fixture.
- State that any light emitting lamp, or luminaire lens, shall not extend beyond the shielding of the fixture and be fully shielded.
It contains the following definitions:
- Light pollution shall mean any artificial light which causes a detrimental effect on the environment, astronomical research and or enjoyment of the night sky, or CAUSES UNDESIRABLE GLARE OR LIGHT TRESPASS.
- Light trespass shall mean artificial light that produces an unnecessary and unwanted illumination of an adjacent property.
- Glare shall mean artificial light that causes annoyance, discomfort, or loss of visual performance and visibility.
We contend that the newly installed LED street lights violate the letter and/or intent of Ordinance 1966 in all of the following ways.
- Although “fully shielded” against uplight, the blue rich white LED light source and luminaire design currently installed, pose detrimental effects in several areas by emitting significant light in the glare zone (above 70 degrees relative to nadir) which in turn causes light trespass into residential windows and causes disability glare for pedestrians. This is in direct violation of City Ordinance 1966 which provides for limiting and/or prohibiting light trespass on an adjacent property and the restriction of light quality which poses glare hazards for pedestrians and motorists.
- Established peer review scientific research has demonstrated that excessive blue spectrum component of LED radiation, similar to that of the light source installed in Davis, has a number of potentially significant and deleterious impacts on people and the environment. In summary these include:
- Increased artificial sky glow due to increased Rayleigh scattering in the atmosphere. Here in Davis, independently documented collected data establishes a 14% increase of sky glow directly attributed to the replacement of the older high pressure sodium streetlights with the newer LED street lighting. This type of light further limits the enjoyment of the night sky and dramatically limits the suitability for astronomical research.
- Excessive glare from lights, as a function of spectrum and source luminance, can cause temporary blindness and excessive discomfort and disability glare in all ages. Glare results in decreased visibility at night for persons over the age of 42 (causes age related disability glare) and promotes longer periods of light/dark adaptation for senior pedestrians and motorists alike.
- Blue light in particular has detrimental effects on human health, and on plants and animals, as well. Extensive and well established scientific research over the past two decades shows that natural biorhythms are set by exposure to the blue frequencies in white light, and exposure to these frequencies at night interferes with and alters the biorhythms of humans, plants and animals.
As publically stated and privately expressed previously by a number of concerned citizens, including the professional opinion of lighting experts living in the community, we believe that the necessary actions to remedy the situation include:
- Install new LED luminaires with improved shielding equal to the “flat lens cobra head” of the high pressure sodium predecessors: new luminaries must feature glare shields that prevent light trespass onto homes and reduce glare potential for motorist and pedestrians.
- Replace all installed LED streetlights with the following: Residential areas to provide for high CRI ( > 85 ) 2700K with photometrics providing for less than 10% of the radiant energy in the blue spectrum( 430 – 490 nanometers). Roadway areas to provide high CRI ( >85% ) 3000K light source with less than 10 % of the radiant energy in the blue spectrum.
- Eliminate the cobra head style of luminare and limit the spectrum to blue-free amber light sources for path lighting, bikeways, parks, pathway, greenbelt, and other environmentally sensitive areas. An alternative light source to include filtered white LED’s (<2000K) with zero emission of blue spectrum below 500 nm. As in current and established practice throughout US National Parks, we also recommend “indirect” design style luminaires for either the LED or blue-free amber light sources.
- Establish a committee to measure, monitor, advise and report on light pollution, total lumens and energy consumption. This committee must include representatives from the following groups:
- A representative familiar with visual needs of an aging population.
- Persons engaged in astronomy and other aspects of nature appreciation and preservation that are related to dark skies.
- Experts in the lighting science, independent of industry
- Establish a process for street light removal when requested by the residents concerned. Currently, once installed, a street light can never be removed. Excess lighting can be wasteful, unaesthetic, reduces property values, can reduce visibility, and affects human health and the environment.
Barbara Clowers is a long time resident of Davis, former owner of an “innovative” small business located in Davis, parent of grown children, member of the International Dark Sky Association, cursed with six unshielded street lights and married to an amateur astronomer who enjoys astrophotography.