‘LIGHT POLLUTION’ : A detailed study on effects of ALAN

KASHYAP.V.MTE-468

Light pollution (Def.s):

•Light pollution, also known as photo pollution or luminous pollution is excessive, misdirected, or obtrusive artificial light.

•Scientific Explanations

Alteration of natural light levels in the outdoor environment owing to artificial light sources

Light pollution is the alteration of light levels in the outdoor environment (from those present naturally) due to man-made sources of light. Indoor light pollution is such alteration of light levels in the indoor environment due to sources of light, which compromises human health

Light pollution is the introduction by humans, directly or indirectly, of artificial light into the environment

Classification of Light pollution:

Light pollution is a broad term that refers to multiple problem now according to the problems they have been further classified

•Glare

•Skyglow

•Light Clutter

•Light Trespass

Glare:

GLAREIt is a visual sensation caused by excessive and uncontrolled brightness. It can be disabling or simply uncomfortable

Blinding glare Disability

glare

Discomfort glare

• describes effects such as that caused by staring into the sun

• It is completely blinding and leaves temporary or permanent vision deficiencies

•describes effects such as being blinded by oncoming car lights, & reducing contrast,

•as well as reflections from print and other dark areas that render them bright, with significant reduction in sight capabilities

•does not typically cause a dangerous situation in itself, though it is annoying and irritating at best. It can potentially cause fatigue if experienced over extended periods

Example of lighting that can result in disability and discomfort glare

Sky Glow•Sky glow refers to the glow effect that can be seen over populated areas.

• It is the combination of all light reflected from what it has illuminated escaping up into the sky and from all of the badly directed light in that area that also escapes into the sky being scattered (redirected) by the atmosphere back toward the ground.

time exposure photo of New York City at night shows skyglow , one form of light pollution

Light Clutter

•Light clutter refers to excessive groupings of lights. Groupings of lights may generate confusion, distract from obstacles (including those that they may be intended to illuminate), and potentially cause accidents.

•Clutter is particularly noticeable on roads where the street lights are badly designed, or where brightly lit advertising surrounds the roadways

•Clutter may also present a hazard in the aviation environment if aviation safety lighting must compete for pilot attention with non-relevant lighting. For instance, runway lighting may be confused with an array of suburban commercial lighting and aircraft collision avoidance lights may be confused with ground lights

The Las Vegas Strip displays excessive groupings of colorful lights. This is a classic example of light clutter.

Light Trespass•Light trespass occurs when unwanted light enters one's property, for instance, by shining over a neighbor's fence.

• A common light trespass problem occurs when a strong light enters the window of one's home from the outside, causing problems such as sleep deprivation

widespread trespassing occurring outside a grocery store parking lot

Scotobiology & LP relating study and findings :•Plants developments usually occurs by seasons and they detect seasons by duration of darkness

•Thus categorized plants into short day plants and long day plants ,short day plants require long nights and long day plants require short nights.

•Short-day plants normally bloom in the autumn when the days are shorter. Long nights initiate the onset of flowering, and later, as nights lengthen, the onset of dormancy, which enables plants to withstand the vigours of winter.

• If short-day/long-night plants are illuminated even briefly during a long night, they detect this as two short “nights”, under continuous night-time light pollution plants respond as if there were no night. In either case flowering and development are compromised.

Cont….

•The effects of light pollution are also considerable at the community and ecosystem level. Disturbance of plant and animal life-cycles within a community affects the survival of otherwise unaffected members.

•Human health is more severely affected by light pollution than is generally realized. As Human hormone regulation, physiology and behaviour have evolved in a diurnal pattern of night and day

Need for Light and Dark -Human Body Aspect•Humans evolved under both light and dark night cycle, modifying it will lead to health risks ,dark night is equally important to light period for proper human health and well being.

•Cyclic daylight and dark night exposure controls the fluctuations of body’s production of various hormones and this is known as Circadian rhythms with about a 24 hr period.

•According to these circadian rhythms the hormones can be classified into two general categories, visible light producing hormones(460 – 500 nm) and dark light producing hormones (> 600nm).

•The below two tables shows the various hormones and the relative body functions

Circadian Blue Light 460 – 500 nm, Morning 6 – 10 am

Neurotransmitters

Cortisol SerotoninDopamine

stress responseimpulse control, carbohydrate cravingpleasure, alertness, muscle coordination

Neurohormones

CRFGastrin Releasing PeptideNeuropeptide YFSHTSH

Stresshungerhungerreproductionmetabolism

Circadian Dark Response – above 600 nm No circadian blue after 10

pm

Neurotransmitters

Melatonin

Vasoactive Intestinal PeptideGrowth Hormone

Sleepblood pressuredecreased body fat

Light pollution : Human EffectsCircadian Rhythm changes and problems associated with it:

•The production of melatonin is associated with circadian rhythms, and changes in that will give a mix of health problems.

•The human immune response consists of two major pathways: Th1 (T helper 1) [cell mediated immunity], which uses N-Killer (NK) cells and cytotoxic T cells to destroy viruses and cancer, and Th2 (T helper 2) [humoral or antibody-mediated immunity], which enlists B cells to produce specific antibodies to help eradicate bacteria, parasites, and toxins

• Autoimmune diseases (asthma, rheumatoid arthritis) by imbalance in Th 2 are more prevalent in the morning,

•while light at night prevents the nocturnal melatonin production, preventing the activation of the anti-cancer N-Killer (NK) cells and cytotoxic T cells which in turn increase the risk of cancer (breast and prostate).

•Night time workers have an increased risks of getting cancer due to disrupted production of melatonin.

•Contrast Sensitivity•Color perception•Our ability to see contrasts

ALAN (Artificial Light At Night) and sleep disorders•Weight gain•Stress•Depression•Diabetes

Glare On eyes and problems associated with it

Light Pollution –Wild life Effects

LP (Light pollution) Effects on mammals:A decline in reproduction, leading to a shrinking population

Difficulty foraging for food due to too much light

Exposure to predators that would otherwise be unable to see them

Increased mortality caused by impairment of their night vision.

Examples of these affected mammals are bats, raccoons, coyotes, deer and moose

LP effects on Birds: Many species of birds migrate or hunt at night .This dependence on darkness makes them extremely vulnerable to bright lights in areas that are naturally dark.

•Collisions with lighted building and towers causes death of many birds. It has been estimated that almost 100 million birds dies per year due to this collisions.(North America).

•Not wanting to fly back into the dark, they continue to fly in the light’s beam until they are exhausted, fall or become prey

•The artificial lights can also cause migrating birds to wander off course and never reach their natural destination.

•Marine birds have been known to collide with lighthouses, wind turbines and drilling platforms at sea.

Light Pollution Effects on AmphibiansThe haze from sky glow extend far beyond the borders of an urban city, impacting the environment for miles, including wetlands, the natural habitat of amphibians. It causes amphibians and other creatures of the marshes to become confused and disoriented, causing,

•A decrease in reproduction ,resulting in lower populations•Reduced foraging for food and lower body weight•Confusion of natural instincts that protect against predators and

Light Pollution Effects on ReptilesReptiles are greatly affected by light pollution, Nocturnal reptiles become disoriented by the artificial light invading their homes and experience a change on natural behaviors. These behaviors might include:

•Appetite problems resulting in decreased weight•Decrease in mating, resulting in diminished populations.•Increased vulnerability to natural predators and unusual ones like cars and humans.

The one of the worst affected reptile by light pollution is Sea turtles,

• Female sea turtles like to nest on remote and very dark beaches. Coastal lights interfere with their ability to find a safe nesting area for their eggs.

•Sea turtle hatchlings crawl instinctively toward the relative safety of ocean because of it’s reflection of the moon and stars. For centuries, this reflection was the brightest point of light on a beach. •Artificial lights can confuse the hatchlings and cause them to crawl away from the ocean and onto roads or into communities. If they do not find their way back to the ocean , they could become fatally exhausted or dehydrated

Light Pollution effects on InsectsMoths and other insects are attracted to artificial lights and may stay near that light all night. This activity round the light

•Expends too much energy and interferes with mating and migration, causing population reduction

•Makes them easy prey for bats and other nocturnal predators, further reducing their numbers Impacts all species who rely on insects for food or pollination

Light Pollution –Plant life effects•Most night lighting (ALAN) does not have the intensity to affect photosynthesis, but it might affect trees that are sensitive to day length. Artificial lighting, especially red light , extends the day length and can change flowering patterns, and most importantly, promote continued growth thereby preventing trees from developing dormancy that allows them to survive the rigors of winter weather.

Measurement of Light Pollution And it’s UnitsLight

Photometry• the measurement of light, in terms of its perceived brightness to the human eye

• It is based on the sensitivity of our eyes to different wave length of light

Radiometry •Radiometry is a set of techniques for measuring electromagnetic radiation, including visible light

• characterize the distribution of the radiation's power in space, as opposed to photometric techniques.

•Luminance (photometric quantity)(how bright a spot is)Luminance is a photometric measure of the luminous intensity  per unit area of light travelling in a given direction. It describes the amount of light that passes through, is emitted or reflected from a particular area. The SI unit for luminance is candela per square meter  (cd/m2)

•Illuminance (Radiometric quantity)Amount of light hitting some surface is a useful integral measure in case of light. it it is measured directly by a luxmeter; the quantity is then illuminance, its unit is lux

Measuring Light pollution:

relative light pollution = man-made part of any photometric or radiometric quantity

natural part of the same quantity

In most cases, it is preferable to express pollution this way: as a dimensionless number rather than by photometric units.

Double Relatively

Ratio of two contrast = Contrast polluted

Contrast Clean•which are determined for a polluted and an unpolluted situations, is the best measure of pollution, as regards the visibility of faint lights.

Where,Contrast = luminance of target – luminance of background luminance of background

Control Of Light pollution

Lighting Scheme Changes

Creating Environmental Zones

Design Aspects

Full cut off lighting Fixtures

usage of different types and colors of light

Usage of automated light sensors

Limit Growth in installed lighting

How Lp Occurs

Lighting Scheme Changes:

•Light Sources•Luminaries•Installation

Light Sources: Light Sources Emitting ultraviolet radiations should be avoided.(According to European Commite’s SCENIHR CFLs may pose an added health risk due to the ultraviolet and blue light emitted)Light Sources Emitting blue light should be avoided in night works(White LEDs  with high color temperature emit proportionally more blue light, and International Dark Sky Discourages the using white light sources with correlated color temperature above 3,000K

LuminariesThe most sensitive/critical zones for minimizing sky glow are those between 90ο and 100ο as shown in Figure and referred to as the lower, upward light output zone (UL)

InstallationKeep glare to a minimum by ensuring that the main beam angle of all lights directed towards any potential observer is not more than 70ο. Higher mounting heights allow lower main beam angles, which can assist in reducing glare

When lighting vertical structures such as advertising signs, direct light downwards wherever possible. If there is no alternative to up-lighting, as with much decorative lighting of buildings, then the use of shields, baffles and louvres will help reduce spill light around and over the structure to a minimum.

Environmental zonesIt is recommended to divide the various areas into different environmental zones and provide specific lighting environment in each of them.

Environmental Zones

Zone

Surrounding Lighting Environment Examples

E0 Protected Dark UNESCO starlight Reserves, IDA Dark Sky

Parks

E1 Natural Intrinsically dark National Parks, Areas of outstanding

natural beauty etc

E2 Rural Low district brightness Village or relatively dark outer suburban

locations

E3 Suburban Medium district

brightness

Small town centers or suburban locations

E4 Urban High district brightness Town/city centers with high levels of night

time activity

Where an area to be lit lies on the boundary of two zones the obtrusive light limitation values used should be those applicable to the most rigorous zone.NB: Zone E0 must always be surrounded by an E1 ZoneDesign Aspects

ULR = Upward Light Ratio of the Installation is the maximum permitted percentage of luminaire flux that goes directly into the sky.Ev = Vertical Illuminance in Lux - measured flat on the glazing at the centre of the window. I = Light Intensity in Candelas (cd) L = Luminance in Candelas per Square Metre (cd/m2)

 

Full Cut Off Lighting Fixtures

By far the best choice for lighting (apart from switching lights off altogether) is the ‘Full Cut-Off’ lighting fixtures which direct their light output down only.

Full Cut-Off Lighting

•A luminaire light distribution where zero candela intensity occurs at or above an angle of 90º above nadir

•This should be the preferred type of light fitting. Full cut-off fittings provide excellent performance in all situations, from the illumination of streets to sports arenas and outside lights

Cut-Off Lighting•A luminaire light distribution where the candela per 1000 lamp lumens does not numerically exceed 25 (2.5 percent) at or above an angle of 90º above nadir and •100 (10 percent) at or above a vertical angle 80º above nadir. This applies to all lateral angles around the luminaire

Semi Cut Off lighting A luminaire light distribution where the candela per 1000 lamp lumens does not numerically exceed 50 (5 percent) at or above an angle of 90º above nadir and 200 (20percent) at or above a vertical angle 80º above nadir. This applies to all lateral angles around the luminaire. These types of fittings should be prohibited in ecologically sensitive areas

A luminaire light distribution where there is no candela limitation in the zone above maximum candela. These types of fittings should not be permitted by planning law

Use of different types and colors of light•Adjusting the type of lights used, so that the light waves emitted are less likely to cause severe light pollution is important•This can include replacing older high pressure mercury vapor lights with high pressure sodium vapor lamps and combining them with “full cut-off luminaries” to reduce energy waste and glow

•Different wavelengths of light have different attractiveness to animals. White lights appear to be the worst offenders for bird attraction, with yellow lights performing better in this aspect. Red and blue lights are the least attractive. This may be important in the construction of tall buildings with lights on top of them and in the lighting of cranes etc

No Cut off Lighting

Turning lights off using a timer, occupancy sensor or manually •Outdoor lights can be activated by motion sensors rather than a switch. These motion sensor lights not only save energy but also reduce levels of light pollution.

•Many motion detectors can be set so that they are less sensitive to the movement of small animals. Particularly in the case of security lighting, Passive Infra Red detectors (PIR) should be used whenever possibleLimit Growth in Installed Lighting

•Limits to the increase of the new installed flux should be implemented.

• A 1% yearly increase could be allowed at first for each administrative area, followed by a halt in the increase of total installed flux, and then by a decrease

•This does not mean that no new installation will be allowed, but simply that if you want to install new lights you have to decrease the flux in the existing overlighted areas.

Lighting regulationsFew countries in the world has separate regulations for the control of light pollution, which include US, Czech Republic, Italy, Slovenia, England and Scotland (according to International Dark Sky Association database)UNITED STATES OF AMERICA

In US, each state has established their own separate standards for controlling light pollution, (16 out of 50) states has implemented these.

Arizona:•AZ House Bill Title 49

California:•California Energy Commission (CEC) Title 24: Energy Efficiency Standards for Residential and Nonresidential Building

•Outdoor Lighting Zones - 2005 Building Energy Efficiency Standards

•CEC 2005 Building Energy Efficiency Standards, Section 132-Outdoor Lighting Controls and Equipment •CEC 2008 Building Energy Efficiency Standards, Section 132-Outdoor Lighting Controls and Equipment

INDIA: In India a National Lighting Code (NLC) has been established, SP 72:2010 by BIS it briefly covers the following aspects of light pollution related factors,

a) Guidance on illuminating engineering practices to be followed by various types of occupancies.

b) Guidance on good engineering practices to be followed in the design, selection, installation and maintenance of lighting systems for indoor and outdoor areas

c) Matters related to the science of illumination such as physics of light, electric light sources, luminaries and photometry

d) Coordination aspects to be considered while designing the lighting systems such as day lighting

e) Aspects relating to energy management and energy conservation in lighting installations including guidelines for design and good practices to be adopted for effective and efficient use of light sources.

Case Study: Light Pollution in Hong-Kong

Hong Kong is one of the most densely populated cities around the world and the worst affected by light pollution (By Peter Shadbolt, CNN March 21, 2013) In Hong Kong and many other major Asian cities, companies compete for business by setting up large flashing signs and billboards

•In an attempt to draw a potential customer’s eyes, the owners make their billboards flash rapidly and intensely. Since Hong Kong is so densely populated, many businesses have sprung up in the area, leading to a greater competitive atmosphere and creating a drive for bigger and more visible advertisements

Methodology

The goals of project were two-fold: (1) to determine the extent to which light pollution is perceived as a problem by the people living in Hong Kong and (2) to recommend applicable lighting ordinances for reducing light pollution in Hong Kong

Sources of Light Pollution in Hong Kong

•One of the objectives was to determine what the most problematic sources of light pollution are for the people of Hong Kong. Using the information collected from our survey, field observations, and interviews we were able to estimate which light sources contributed the most to light pollution.

•the mean perceived contribution to light pollution for each of the sources on a scale of 0 to 6, where 0 is ‘None Whatsoever’ and 6 is ‘Highly Excessive

Perceived Levels of Lighting

Perceived level of brightness Level of desired brightness

• A great number of respondents felt the current level of light outside their residences at night is halfway between being bright as day and dark as night, i.e. levels 2 to 4

•The graph on the right of shows a large portion of our respondents desire lower levels of lighting, i.e. levels 0 to 2. •the average perceived level of brightness is 2.7, where the average level of desired brightness is 1.5. This difference of 1.2 shows a major shift towards lower levels of lighting

Perceived health effects of artificial lighting

Recommendations for proper controlling LP•Infraction of light pollution ordinance results in monetary penalty•All lights in certain zones must be off between certain hours of the night•Light fixtures should be fully shielded and directed at its intended target•A person may not direct any amount of light past his property lines without express permission from the neighbor•A special court may be set up which deals with light pollution infractions in a civil court (similar to small claims court)•Limitations on light fixtures•Video billboards require government permits in order to be installed•More researches for Light pollution in Hong Kong

CONCLUSION

•LP is a byproduct of industrial civilization, majorly from building exterior and interior lighting, advertising, commercial properties, offices, factories, streetlights, and illuminated sporting venues.

•As we have seen how drastically it affect our health (Humans),Plants and animals it must be reduced .

•The most lucky factor behind light pollution is that it can be easily reduced by adopting simple measures

•By controlling Light pollution we are also reducing energy wastage

•The need of laws for controlling light pollution is a must ,and in an ever growing country like India ,by proper implementation of LP controlling ordinances will help to solve this problem at an early stage

•Proper education of people for the need of darkness and various factors relating to Light pollution must be reaching to common people.