Light Pollution

I. Introduction - The Need for Action

The night sky over Britain is more brightly lit than in any other country in Europe, apart from The Netherlands. The problem is becoming increasingly serious. During the 1990s, the area in England with pure, dark skies reduced by some 27%.

We, in the Oswestry Borough, are comparatively lucky, as we live in an area where light pollution has not yet entirely blotted out the Milky Way. This night darkness is something that we need to cherish and maintain. It is an important feature of a rural area, as are the trees, hedgerows, lapwings and orchids. It is a defining aspect of our community. Were we to lose it, we would be losing a precious feature of our local environment.

But, each year, light pollution becomes worse. This paper shows that external lighting, well designed and positioned, can provide more effective lighting with improved security and potential energy savings, and sets out some recommended best practices.

II. What is Light Pollution?

Light pollution is every form of artificial light which shines outside the areas it is intended to illuminate.

This includes all light which is directed or "leaks" above the horizontal into the night sky or which causes glare or other nuisance.

There are different types of light pollution:

Sky Glow: The orange glow we see over towns and cities caused by upwardly directed or reflected light. This can often be seen from rural areas many miles away.
Light Trespass: Any light shining where it is not needed or wanted. Examples include street lights shining into gardens and windows of adjacent houses.
Glare or Dazzle: Excessively bright and misdirected light can cause discomfort or danger.

III. What are the sources of light pollution?

The major sources of light pollution are street lighting, security lamps, advertising and architectural lighting, floodlights for commercial, sporting and parking facilities.

Street lights

While poorly directed street lights are a major cause of sky glow, the impact of street lights on individual homes can also be particularly unpleasant. Street light flooding in at bedroom windows or illuminating people's gardens can cause nuisance and reduce night time privacy.

Light pollution from street lighting has been compounded by the replacement of the old sodium lights with much brighter high pressure sodium lighting. However, well designed and directed high pressure lights can reduce light pollution and nuisance, if light spillage is controlled by installing full cut-off units, which direct the light downwards onto the public highway.

Security lights

Industrial, commercial and domestic security lighting tends to use fittings which are too bright and poorly designed or installed. These installations frequently allow light to "trespass" outside the designated area, causing irritation and sometimes dangerous dazzle.

A very cheap and commonly available domestic "security light" is fitted with a 500 Watt bulb where a 150 Watt or less would be quite sufficient, and indeed provide better security by reducing hard, dark shadows and dazzle or glare.

It is generally assumed that the greater the external lighting the better the security, but most break-ins occur in daylight. When operating at night, burglars prefer well lit premises so that they can see what they are doing and can move about easily in the shadows. The Government's crime reduction web-site shows that "lower levels of lighting provide more efficient security than higher levels of lighting. It is only when a light is angled downwards that an intruder becomes fully visible. Until that point is reached, the light does more to conceal than reveal".

Architectural lighting

This is illumination of warehouses, shops, pubs, churches and other buildings for advertising or aesthetic purposes. Frequently a flood light is installed at ground level and directed upwards onto the building. A great deal of this light misses the area that it is intended to cover and invades adjacent buildings and the sky. These lights tend to be left on all night rather than being controlled by time clocks or motion sensors.

Facility flood lighting

Sport grounds, car parks, and industrial premises are often floodlit to provide usable light, safety or security. Often the light fittings used are excessively bright and poorly designed leading to all forms of light pollution.

IV. Impact of Light Pollution

Impact on humans

In a simple sense light pollution "steals" away the darkness, taking away from us all the wonder of the night sky.
In many cases, it becomes a serious nuisance due to light trespass, dazzle and glare.
In extreme cases, light pollution can cause real suffering to those affected, depriving them of sleep and resulting in serious health problems.

Impact on wildlife

Light pollution has been attributed to migrating birds colliding with illuminated buildings.
It causes a false dawn which disrupts the behaviour of birds and other creatures.
It causes the death of moths and other insects as they are attracted to the light (possibly a factor in the recent decline in urban moth populations). This results in loss of food for bats and birds and badly effects pollination of trees and other plants.
It disrupts tree and plant habits that are controlled by day length (e.g. leaf fall and flowering).

V. Conserving Energy.

It is clearly desirable to cut energy use to the minimum level needed, while ensuring that external lighting provides the desired level of illumination. Thus it is important to ask some key questions before installing external lights.

Do we really need to illuminate this area?
What level of light is really needed?
Can the lights be turned off (e.g. at 11.00 pm) or made movement sensitive?
What is the most effective way (lowest cost + adequate illumination)?

VI. Recommended Best Practice

There is a wealth of useful information and guidance available from the National Lighting Product Information Program (NLPIP), the Institution of Lighting Engineers (ILE) and the Campaign for Dark Skies (CfDS). We have attempted to boil their guidance down to some simple "Best Practice Guidelines", which we believe should be adopted immediately by Oswestry Borough Council. At the same time we would like to see the Council publishing a robust and explicit policy statement on light pollution, which should then be included in the Unitary Development Plan.

Planning

The Institution of Lighting Engineers states that:

The best method of dealing with light pollution is at the planning stage. This is an ideal time to influence the design or installation of lighting schemes, and

Local Planning Authorities should specify the following environmental zones for exterior lighting control within their Development Plans:

Zone 1 Intrinsically dark landscapes (National Parks, Rural Areas and Areas of Outstanding Natural Beauty)
Zone 2 Low district brightness areas (Small villages or relatively dark urban locations)
Zone 3 Medium district brightness areas (Small town centres or urban locations)
Zone 4 High district brightness areas (Town/city centres with high levels of night time activity)

The key principle is that lighting should always be set at the lowest level necessary in the circumstances.

Best Practice Guidelines:

General Rules for External Lights

External lights should be designed to light only the property on which they stand and not that of a neighbour. For instance, the light on sports grounds and car parks should be confined to the pitch, court or park being lit.

In addition, all external lights should face downwards so that the source of the light, the bulb and the glass surrounding it is visible only to someone standing in the area that the light is designed to illuminate.

Street Lighting - All street lighting should have full "cut off" lights to avoid light "trespassing" onto private property. Where ever possible, street lights should not exceed first floor height, to reduce intrusion of light in residential areas.

Rural Areas - In rural areas, street lighting is not appropriate and should only be installed if it is absolutely necessary. This will help to maintain the distinction between town and country.

Security Lights - Security lights should, in addition to being aimed downwards, be motion operated wherever possible.

These rules should apply to all public premises, including street lighting, and all private premises.

It is our hope that these "Best Practice" Guidelines will be adopted as formal guidelines by the Borough Council and subsequently included within the new Local Development Framework (LDF).

There is hope for the future

Modern lighting design can already provide street lighting that is energy-efficient, does not over light an environment and directs light only where it is wanted.

The Highways Agency, backed by the Department of Transport, has begun to address lighting on trunk roads and is now fitting or retro-fitting full cut-off lighting (units which do not emit light above the horizontal).

The Clean Neighbourhoods and Environment Act 2005 added artificial light as a statutory nuisance. Local authorities and Environmental Health Practitioners now have the power and a duty to resolve issues arising from nuisance artificial light.

Conclusion

Everyone should be entitled to see the Milky Way in the night sky. To achieve this, guidelines and controls are required, not necessarily to ensure less light, but to ensure better light.

Darkness at night is normal. Unfortunately, people have become so used to a high level of artificial lighting that they often ignore and accept without questioning its adverse effects. In order to rectify this situation, a culture change is needed. This has already occurred with public attitudes in relation to dropping litter, dog-fouling, drink-driving and wearing seat-belts. Now we need to see the same happen with regard to lighting.

Charles Lillis and Charlie Burton