SCIENTIFIC ARTICLES

~ Aiming for Good Lighting Environments ~

March 1998

II. "Light Pollution Countermeasure Guidelines"

1-1 Environment impacts of lighting

The effects of outdoor lighting on the sunounding environment can be summarized as follows;
(1) Effects on plants and animals
(a) Wild plants and animals
(i) insects
(ii) mammals, amphibians, reptiles
(iii) birds
(iv) fish
(v) plants
(vi) ecosystem
(b) Crops and livestock
(i ) crops
(ii) livestock

(2) Effects on human activities
(a) Effects on astronomical observation
(b) Effects on inhabitants
(c) Effects on pedestrians
(d) Effects on transportation system
(i) Automobiles
(ii) boats and airplanes

(i) Good lighting environment
A good lighting environment is a state in which safe and efficient lighting, using an appropriate objective and technology based on the surrounding conditions (social conditions and natural environment) is installed and scenic views and the sunounding environment are taken into suffcient consideration when setting up the lighting.

(ii) Spill light/stray light
Light emitted by lighting installation which falls outside the targeted area or boundary.

(iii) Obtrusive light
Spill light which, due to the amount or direction of the light, or both, has a deleterious effect on human activities, other living organisms, etc.

Light pollution is defned as obstruction of the formation of a good "lighting environment" by spill light . or the deleterious effects due to such an obstruction. A shorter defnition would be adverse effect due to obtrusive light.

The effects of lighting on the surrounding environment can be summarized as follows;

(1) Effects on plants and animals

(a) Wild plants and animals

(i) Insects
Some insects, such as moths, are phototactic (attracted by light), while others such as fireflies are lucifugal (dislike and therefore avoid light). For both of these insect species, the effects of nighttime lighting are significant.

When there are rice fields, mountains and forests, rivers, and lakes located close to a lighting installation, there is the possibility of an increase in the number of insects flying by, depending upon the season, and the disappearance of some species may become ¨ problem in some instances. In such cases, it is desirable to (a) use light sources with a
wavelength that has a low degree of attraction for insects, and (b) to use luminaires that do not emit light in the direction of the insect habitats.

(ii) Mammals, amphibians and reptiles
. The environmental effects of night ligbting on the habitats of nocturnal mammals such as raccoon dogs (tanuki in Japanese) are significant. Many species of mammals, amphibians and reptiles come to feed on insects that gather at lights during the night, and for this reason it is important to take care of their habitats.

(iii) Birds
It has been reported that the distribution of bird habitats has been changing in conjunction with the urbanization of suburbs which still have some natural environment remaining. In particular, it is feared that nighttime lighting will have effects on birds of prey such as owls and other species which live in forests. However, there are still many
unresolved aspects concerning the quantitative effects of nighttime lighting on birds so future research is being anticipated.

(iv) Fish
While some fish species are attracted by light others tend to avoid it. Furthermore, different species react differently depending upon the illuminance or type of light. Future research is needed since the effects of lighting on fish are still unknown and appropriate illuminance levels are not known.

(v) Plants
It is possible that nighttime lighting has an effect on plant physiology and plant ecosystems. There have been reports on the effects of lighting on the physiology of photosynthesis and growth and biological seasons, effects on bud formation in short day plants and long day plants, effects on pollinating insects, and so on. It has been confirmed
that artificial lighting has different effects on different species of roadside plants in urban areas. For example zelkova and gingko are not affected by light while liriodendron (tulip tree) and Chinese parasol are affected.
Therefore, it is desirable that nighttime lighting installations be set up at appropriate locations and that various other factors, depending upon the plant species, such as the wavelength and intensity of the light, the season and time of lighting, and so on are adequately considered.

(vi) Ecosystems
Many points concerning the impact of nighttime lighting on entire ecosystems, including wild plants and animals, remain unclear so future research in this subject is being keenly anticipated.

(b) Crops and livestock .

(i) Crops
The effects of artificial light on agricultural crops such as rice and spinach are well understood. Rice is ¨ short day plant and rice ear formation is delayed by nighttime light. This effect is believed to be the strongest from 20 ~ 40 days before ear formation so it is necessary to be careful when setting up lighting installations on roads in the vicinity of rice paddies.

(ii) Livestock
It is conceivable that inappropriate outdoor lighting may have a variety of effects on livestock, such as the disruption of physiological and metabolic functions of livestock and poultry, a decrease in production capacity, and abnormal behavior in the animals. Therefore,be sure to take the habits of the animals into consideration when setting up
lighting close to livestock, etc:

(2) Effects on human activities
(a) Astronomical observation
Light in urban areas has a negative effect on astronomical observation caused by a brightening of the night sky due to dispersion of the light by moisture and dust particles in the atmosphere. When it is anticipated that lighting close to an observatory will affect astronomical observations, measures which will prevent this from occurring should be
adopted.

(b) Effects on residents (windows of dwellings)
It is feared that outdoor lighting, such as road and street lights, which shine into dwellings will have a deleterious effect on the privacy and restful sleeping of residents. The Commicsion Internationale de 1'Eclairage (CIE) has set a maximum illuminance for light coming in the windows of residential dwellings. It is desirable to decrease the
illuminance of the window surface as much as possible. Measures to ensure this include studying the height and location of lighting fixtures as well as installing shades and louvers on light fixtures to control the spatial distribution of the luminous intensity.

(c) Effects on pedestrians
Improper selection and installation of street lights and other lights may not only result in insuffcient illuminance, but may also cause glare for pedestrians. There is also the of losing the anti-crime effect (i.e., safety) if the lighting is inappropriate. Therefore, it is important to install luminaires which are suitable based on the conditions of the
sunounding environment.

(d) Effects on transportation systems

(i) Automobiles
It is possible that the lighting of buildings and other faclities situated close to roads affects drivers and thus may hinder traffic safety Therefore it is necessary to use lighting stipulated by JIS and other specifications.

(ii) Boats and airplanes
It is conceivable that city lights and port facility lights have a deleterious effect on the recognition of marine lights and shipping lane markers.