Outdoor lighting is used to illuminate roadways, parking lots, yards, sidewalks, public meeting areas, signs, work sites, and buildings.
It provides us better visibility and a sense of security. Most street lights shine light not only on the nearby ground, where is needed, but also miles away and skywards. Thus a large fraction of the light is lost, or may cause ill environmental effects.
Effects of light pollution
i) Urban light pollution threatens street trees, flora in nature reserves, parks and gardens. Upwardly directed floodlighting of trees disorients and dazzles nocturnal animals and insects.
ii) Exposure to intense floodlighting sources may result in permanent photochemical retinal damage in animals as well as in humans.
iii) Some marine and aquatic creatures are known to be affected, including endangered species.
iv) Light pollution and light trespass represent unnecessary greenhouse gas production.
Control of light pollution
i) Outdoor light fixtures should be designed so that they direct light only to where the light is needed. This will result in energy savings, in lower operating costs and more efficient utilization of the light, improved night sky visibility, reduced glare, improved safety and security due to better night visibility, and a more attractive environment
ii) Properly-designed full cutoff lighting reduces operating costs, saves energy and prevents light pollution.
iii) Lighting should be designed, installed and operated to:
1. Control glare,
2. Prevent light trespass onto,
3. Minimize direct upward emission,
4. Promote effective security,
5. Avoid interference with operation of motor vehicle