Your checklist
First steps a city can take towards protecting wildlife from light pollution
Start with natural darkness and only add light for specific purposes.
Artificial light should only be added for specific and defined purposes, and only in the required location and for the specified duration of human use.
Use adaptive light controls to manage light timing, intensity and color.
Advances in smart control technology provide a range of options for better controlled and targeted artificial light management including remotely managing lights, instant on and off switching of lights, control of light color, dimming, timers, flashing rate, motion sensors and well-defined directivity of light.
Light only the object or area intended – keep lights close to the ground, directed and shielded to avoid light spill.
Light spill is light that falls outside the area intended to be lit. Light that spills above the horizontal plane contributes directly to artificial sky glow while light that spills into adjacent areas on the ground (also known as light trespass) can be disruptive to wildlife in adjacent areas. All light fittings should be located, directed or shielded to avoid lighting anything but the target object or area.
Use the lowest intensity lighting appropriate for the task.
Starting from a base of no lights, use only the minimum number and intensity of lights needed to provide safe and secure illumination for the area at the time required to meet the lighting objectives.
Use non-reflective, dark-colored surfaces.
Light reflected from highly polished, shiny or light-coloured surfaces such as white painted infrastructure, polished marble or white sand can contribute to skyglow. In considering surface reflectance, the need to view the surface should be taken into consideration as darker surfaces will require more light to be visible.
Use lights with reduced or filtered blue, violet and ultra-violet wavelengths.
Short wavelength light (blue/violet) scatters more readily in the atmosphere and therefore contributes more to skyglow than longer wavelength light. Most wildlife is sensitive to short wavelength light and, as a general rule, only lights with no short wavelength violet or blue light should be used to avoid unintended effects.
Further actions for cities
- Determine the areas with most light emissions and prioritize actions to reduce light pollution. For example, if most light pollution comes from streetlighting, then the updating and management of this can be prioritized to reduce light emissions
- Consider all light sources at a given site. For example, in a city center street, signs and lights from shop windows may provide enough light for people to walk, meaning that streetlights can be switched off
- Consider spatial distribution of light pollution to ensure that artificial lighting does not form a barrier for species which move or migrate between habitats. Linear lighting, for example along roads in industrial areas, may create a barrier for wildlife