[No. 01] Longcore and Rich: Adverse effects of night lighting at natural-setting playing fields. In the course of the Beach Chalet athletic fields renovation proposal (Golden Gate Park, San Francisco, California) – see http://www.synturf.org/sanfranciscobrief.html (Items 8 and infra.) for earlier posting on the subject - Travis Longcore, Ph.D., and Catherine Rich, J.D., M.A., issued an experts’ analyses on the effects of night lighting from the proposed fields renovation. The report, dated 26 March 2013, along with biographical notes on the experts and all internal citations and studies, is available here. While the field renovations call for artificial turf fields, the subject-matter of the report is of general interest to all natural-setting venues that use lights to illuminate the outdoors playing surfaces. The following is excerpted from the report.
The City of San Francisco has proposed to replace existing turf playing fields at the western end of Golden Gate Park with synthetic turf fields and sports field lighting. The City prepared a Draft and a Final Environmental Impact Report (DEIR/FEIR) for the project and issued a Coastal Development Permit, which was appealed to the California Coastal Commission (Commission). The Longcore and Rich Report is an analysis of the effects of the proposed project on coastal zone resources, with a focus on impacts to biological resources from night lighting.
The proposed lighting system consists of ten 60-foot light standards, each with ten 1,500-Watt metal halide lamps. Therefore, the sports fields will be illuminated by one hundred 1,500-Watt lamps, which the manufacturer claims will produce 134,000 lumens each. The total amount of light will be 13.4 million lumens over 9.4 acres (excluding parking and walkway lighting). As a comparison, a 60-Watt incandescent bulb produces about 800 lumens, which means that the new sports field lighting will be as bright as 16,750 60-Watt incandescent bulbs. The proposed project would create a luminous dome of bright white light where it is currently darker than the surrounding city. This dome, especially under foggy conditions (which occur at least one third of the year), would be the defining visual feature of the nighttime environment in the National Park to the west, and would increase ambient illumination over a wide area to levels that are ecologically disruptive.
The Report concludes that the project goal of a lighted field cannot be achieved without significant adverse impacts on coastal zone resources. The Commission should protect those resources, and in this instance, should only approve a renovated grass field without any of the proposed sports field lighting. Such a recommendation would actually be consistent with the adopted Master Plan for Golden Gate Park, which does not propose any nighttime use at the project site.
The main argument in the project proposal and environmental assessment is that all of that light will be directed downward and consequently will not affect the surroundings. The EIR neglects, however, to properly account for reflection and scattering of light. No matter how shielded, sports field lights cause light pollution.
The angle that light shines on a surface affects the amount of light that is reflected by that surface. Because research on the reflectivity of artificial turf within the visual spectrum of light (390–700 nm) is not readily available, so for the purpose of analysis, one assumes that artificial turf has similar properties and is at least as reflective as natural turf. When light shines straight down on turf, roughly 55% of the light is reflected back upward. When the light is at a 60º angle, as little as 12% of the light is reflected upward. The average amount of light reflected upward from light shining on turf at angles of 60–90º is 20–25%. The light standards for the proposed project are no more than 240 feet from each other and are 60 feet tall, so all of the light will be shining on the turf at angles of 60–90º. Therefore, the proposed project would result in at least 2.7–3.4 million lumens of light reflected up into the sky across the 9.4-acre site from reflection, in addition to the light reflected onto the trees surrounding the site.
Light is scattered by aerosols in the air. These can be dust, pollen, or droplets of water. An assessment of light pollution from the proposed sports field lighting should also consider scattering from molecules in the air, which is known as Rayleigh scattering. This type of scattering increases with shorter wavelengths of light, so the light from proposed full-spectrum lamps will be scattered much more than that from the streetlights along the Great Highway. This is because the streetlights along the Great Highway use high-pressure sodium lamps, which have very little light in the shorter wavelengths of the spectrum, while the proposed sports field project would use metal halide lamps, which produce significantly more light in the shorter wavelengths of the spectrum.
Illumination is important to understand because it has biological effects. Small mammals respond to illumination in their foraging activities. For example, artificial light of 0.3 and 0.1 lux reduced the activity, movement, or food consumption of a cross-section of rodent species. This phenomenon also has been shown in natural (in addition to laboratory) conditions. One lux is roughly 0.1 footcandles, so the amounts of light in these studies were ten times smaller than the resolution of the illumination diagrams in the EIR. Birds can be extremely sensitive to illumination, and extended foraging by species under artificial lights is documented in the literature. Many species of shorebirds and other waterfowl have been recorded foraging or roosting under artificial lights. Effects of increased illumination on bird behavior also include changes in singing times. Those birds that sing earliest are responding to increases in illumination so faint that they are undetectable by humans.
Luminance, and the visibility of lights themselves (whether or not they increase illuminance, the measure of illumination) also affects wildlife species. Even if illumination is not appreciably increased, merely seeing the light from the project can influence animal behavior. One example where luminance probably is as or more important than illumination is that of breeding bird density and lights. The one experimental study of the effect of streetlights on breeding bird density shows a negative impact from lights much dimmer than those proposed for the sports fields. The streetlights in the experiment created a maximum illumination of 20 lux (1.8 footcandles). The adverse effects of these lights (decreased density of black-tailed godwit nests) were experienced up to 300 m (984 ft) from these lights, extending into areas with negligible increased illumination, which means that the adverse impact results from the light being visible, rather than the amount of light incident on the sensitive receptor.
Families of insects are attracted to lights, including moths, lacewings, beetles, bugs, caddisflies, crane flies, midges, hoverflies, wasps, and bush crickets. The metal halide lamps proposed to be installed would generate significant emissions in the ultraviolet (UV) spectrum, which would make them very attractive to insects. Insects attracted to lights are subject to increased predation from a variety of predators, including bats, birds, skunks, toads, and spiders.
The sensitive bird species found within area could be adversely affected by lights. The EIR claims that Western Snowy Plover is absent because of a lack of habitat. Western Snowy Plover does, however, winter along the beach close to the project site and certainly within the range of influence of the proposed lights. A cursory review of eBird data reveals the presence of Western Snowy Plover quite close to the project site. Given that the species is listed under the Endangered Species Act, the project does not have to impact nesting habitat for protections to be required. Rather, any disruption of Western Snowy Plovers habitat of any kind, or the possibility of disruption of the birds themselves, should have triggered consultation with the U.S. Fish and Wildlife Service. The proposed project would significantly increase the ambient illumination on the beach that is used by this threatened species, which could have adverse impacts by increasing predation. The advantages given to predators by additional light have been well documented. While it may seem a benefit for diurnal species to be able to forage longer under artificial lights, any gains from increased activity time can be offset by increased predation risk. The sensitive raptor species found in project area include Cooper’s Hawk. It is documented twice in 2012 at the fields themselves. The is also a likelihood of presence of Red-tailed Hawk as is Red-shouldered Hawk.
Seabirds are particularly attracted to lights at night, presumably because they cue in on bioluminescent organisms while foraging. In coastal regions, seabirds such as storm-petrels are routinely observed at athletic stadia, having been attracted to the lights, including Leach’s Storm-Petrel around the lights of Candlestick Park in San Francisco, and Ashy Storm-Petrel at Stanford Stadium in October 2011. Given that the proposed project is closer to the open ocean than these two sites, it can be expected to attract seabirds, especially during overcast and foggy conditions, when these species fly closer to the shore. This is of particular concern along the California coast because of the documented high level of attraction to night lights exhibited by the two species of Synthliboramphus murrelets, which are of significant conservation concern.
The spectrum of lights proposed increases biological impacts. The environmental analysis for the project does not incorporate any of the voluminous research that shows the differential effects of different wavelengths of light on biological systems. Neither the aesthetics analysis nor the biological resources analysis takes into account the wavelengths of light that would be produced by the proposed project. This light, as produced by metal halide lamps, would be much “whiter” than existing lights in the vicinity of the project. The color temperature of the lights proposed for the project would be 5000 to 8000 K, which is a very “cold” blue light. By contrast, incandescent bulbs produce much “warmer” light that does not have emissions in the shorter wavelengths (blue, violet, and ultraviolet) that are present in light from metal halide lamps. The conclusion from a number of studies on humans and wildlife is that whiter light (that is, fullspectrum light with blue and violet light included) has more adverse impacts. The blue-heavy spectral character of the metal halide lamps has the potential to affect human health because blue light gives a physiological signal to humans (and other organisms) that it is daytime, disrupting circadian rhythms. The wavelengths of light that humans see as blue are 500 nanometers (nm) and shorter. Light of these wavelengths, when sufficiently bright, suppresses the production of the hormone melatonin in humans and other animals. This can occur at levels previously thought to be too dim to have any effect (< 1 lux, while a streetlight illuminates to 15–100 lux). Melatonin is naturally produced at night as humans sleep and provides many health benefits, including playing a role in preventing breast and prostate cancer.
The scientists have shown that regions of the world with high levels of outdoor lighting have higher breast and prostate cancer rates. For example,
• Breast cancer tumors that are grafted onto rats grow much faster when nourished by blood from women exposed to light at night (i.e., low melatonin) than do tumors nourished by blood taken from women who were in darkness before the blood draw (i.e., high melatonin).
• Women who report having more light in their bedrooms are at significantly greater risk of breast cancer than women who report that their bedrooms are dark.
• Globally, breast cancer risk in countries with the brightest outdoor lighting is 30–50% greater than countries with the lowest outdoor lighting, even when accounting for other demographic differences.
• Within a country (Israel), the level of outdoor lighting was significantly associated with breast cancer risk after all other demographic and ethnic variables were controlled.
• Risk of prostate cancer was found to be significantly greater for men living in areas of the world that have the most outdoor lighting, when all other factors were controlled.
• Exposure to light at night and associated sleep disruptions, which can be caused by bright streetlights outside houses and apartments, is also associated with depression, insomnia, mood disruptions, weight gain, and metabolic disruption.
The beach and shoreline ecology is vulnerable to light pollution. The inland end of the beach of the Pacific Ocean is only about 450 feet from the proposed lights. Even though human visitors heavily use this beach, it is also an important habitat for other species, and is especially used at times when human use is lower (e.g., at night). As a general rule, additional light, whether moonlight or artificial light, increases foraging efficiency of predators and reduces activity of prey. This phenomenon has been shown many times in different habitats, including beaches. For example, ghost crabs are active only at night, and avoid activity under both the full moon and artificial light.
Effects from lights near shorelines may also affect aquatic ecosystems. For example, the predator-prey dynamics of fish and marine mammals are affected by lights. In general, additional light provides benefits for predators, except when their prey are schooling species, in which case the predator defense mechanism of a school is enhanced. Shorebirds sometimes forage at night, probably as a defense against predation, and as a result of slightly higher invertebrate activity on beaches at night. Predator defenses of shorebirds are different during the night compared with the day; in an observational study some proportion of Dunlins remain motionless and limit vocalizations as a defense at night while all individuals in a flock fly away in response to predators during the day Some shorebirds forage under artificial lights, presumably because they can do so by sight instead of by touch. Time of foraging in shorebirds is therefore likely the result of tradeoffs between the risk of becoming prey with ability to detect their own prey. The proposed project will affect the ambient illumination conditions for shorebirds on the beach at night, which may adversely impact some species (e.g., small species such as Western Snowy Plovers), while extending foraging times for other species. This should be considered an adverse impact since it further disrupts natural patterns and cycles of illumination.
Curfew on lights does not eliminate impacts. Substantial evidence exists to conclude that even though sports field lights would not be on all night, they still would have a substantial impact on wildlife. The examples use species not present at the park, but illustrate a general ecological principle. First, many groups of species share resources across lighting levels; that is, one species may forage at dusk, another right after dusk, and another in the dark of night. By lighting the fields (and adjacent habitats) the project essentially would eliminate the range of illumination experienced by habitats surrounding the fields. Rather than a smooth range of illumination conditions as the sun goes down and darkness falls, sites will experience a single illumination level until the sports field lights are turned off. For a substantial portion of the evening, this will favor those species that are adapted to the artificial lighting level. As shown in experimental studies on amphibians, the increased illumination levels influence the outcome of competitive interactions. The predicted result of lights, even if switched off at an hour certain, is a reduction in species diversity.
Second, increased illumination, even on a temporary basis, reduces the time available for critical behaviors. The research on frogs illustrates that mating and other reproductive behaviors are highly dependent on lighting levels. If artificial lighting eliminates a significant period of potential breeding time for a species, the long-term consequences will be negative. This is illustrated by the foraging activities of western toad (Bufo boreas), which is concentrated at certain illumination levels. If artificial lighting such as that proposed for the sports fields, or even streetlights, were present in the toad’s habitat until 11 P.M. each night, any such crepuscular species would be deprived of one-half of its available foraging time, a significant impact by any estimation.
