 SCIENTIFIC
ARTICLES
GUIDELINES
FOR LIGHT POLLUTION
~ Aiming for
Good Lighting Environments ~
March 1998
Environment
Agency of Japan
II. "Light
Pollution Countermeasure Guidelines"
1. Definition of light pollution
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
1-2 Defitions of related terms
(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.
1-3 Definition of "light pollution"
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.
1-4 Environmental effects of lighting
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.
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