- [Narrator] The invention
of the electric light bulb,
150 years ago,
was one of the most transformative
milestones in history.
This new form of light, artificial light,
brightened and made
safe once-dark streets,
prolonged waking hours into the evening,
and brought electricity into
homes for the very first time.
Today, this glow has grown, but at a cost.
Light pollution is the over-illumination
of cities and night skies
by artificial lighting.
It's caused by the abundance
of light sources emitting light outside
of an intended direction.
Several types of light pollution
exist, including glare,
which is a disruptive light
that shines horizontally,
light trespass, the unwanted shining
of light onto nearby areas,
and sky glow, a halo over
inhabited areas caused
by the scattering of light particles.
No matter what form light pollution takes,
each can have unintended,
yet harmful impacts.
Wildlife, particularly sea turtles,
have had their nocturnal
patterns disrupted.
The turtle hatchling's
instinct to follow the light
of the moon in order to reach the sea
is intercepted by the
light of inland cities.
Because of this, many never
find their way to the ocean.
Human's well being is also
compromised by light pollution.
The excess light can
overwhelm photoreceptor cells
in the retina, damaging ones eyesight.
Plus, it disrupts natural sleep cycles,
and causes sleep deprivation,
leading to a number of health problems,
possibly including cancer.
Light pollution also
results in the production
of additional carbon emissions.
Each year, potentially billions
of dollars worth of coal or oil,
which are burned to produce electricity,
are wasted on unnecessary light.
Over the past several
decades, light pollution
in North America has increased
an estimated 6 to 10% each year.
A rise fueled by growing populations,
greater access to electricity,
and increased urban development.
Efforts have been made
to help counter this rise
in excess light, including the development
of alternative
energy-efficient light bulbs
and smarter directional lighting designs.
These and other innovations will continue
to refine this 150-year-old technology,
artificial light, and optimize
it, for a brighter future.
(light switch clicks)
