Light Pollution Abatement Site

Calgary Centre

Royal Astronomical Society of Canada


Page last updated March 2, 2008		 LPA Logo

Light and Crime

Fear of increased crime is the most significant concern expressed by people when asked about reducing light pollution. It is commonly believed that nighttime lighting reduces crime, yet studies of crime conclude primarily that only our fear of crime is reduced. Although there is an overwhelming view that all-night lighting prevents crime, crime data do not show a strong relationship between lighting and crime rate.

The belief that lighting reduces crime is widely held and this and related issues have been examined in many places over the past few decades with some surprising results.

Numerous investigations of the supposed relationship of light and crime have been undertaken are listed at http://amper.ped.muni.cz/light/crime/OLCpt2.htm and http://amper.ped.muni.cz/light/ctstarwchr/LiteLynx.htm#crime.

A test in West Sussex, UK showed crime went up in lit areas. In certain test areas, all-night lighting was installed; other areas were kept as control areas. West Sussex Police monitored the crime patterns for comparison with the previous year in both test and control areas and polled residents about their perceptions and the affects of the all-night lighting.

Polling results confirmed people thought lighting prevents crime and most residents felt safer after the all-night lights were installed. Crime statistics, though, showed a 55% increase in crime in the test areas as compared to the control areas and to the county as a whole! West Sussex has subsequently decided against all-night lighting.

And there's another surprise: Police report that such darkness is often safer. That's partly because neighbors soon learn to alert police if they see any lights on in a building. There's even less graffiti because it's usually lighted walls that attract the spray-can vandals, not dark ones.

The San Diego police have gone on record indicating they see no real influence of lighting source on crime levels. Commonly, people's perception about what lowers the risk of crime is not based the facts of the situation.

Vandalism and graffiti have been successfully reduced in many American schools with the Dark Campus Policy that was begun in San Antonio in the 1970s. Vandalism and graffiti-and the associated cost of repairs-dropped immediately when "security" lights were removed or turned off.

The City of Calgary Police Service has also concluded that when and where crimes occur are not related to the amount of darkness available. Calgary crime statistics show that most break-ins occur when a property is unoccupied (homes during the day; businesses at night, despite "security" lights). Assaults generally occur between individuals who know each other and they usually involve drugs, alcohol, or past differences.

Many studies in the United Kingdom and the United States have attempted to understand the relationship between lighting and crime. A comprehensive study was recently concluded by the US National Institute of Justice ( Preventing Crime: What Works, What Doesn't, What's Promising), A Report To The United States Congress, 1997). It used data from existing reports primarily from The United States and The United Kingdom. Social and physical factors and the full spectrum of crimes were considered. The study was critical of most studies because they tend to have poor experimental design. However, the overall conclusion about lighting is: "We may speculate that lighting is effective in some places, ineffective in others and counter productive in others. The problematic relationship between lighting and crime increases when one considers that offenders need lighting to detect potential targets and low-risk situations."

Several British studies have followed proper scientific methodology. A comprehensive study of 100,000 crimes in an inner London area with a high crime rate sought to determine whether new street lighting reduced crime . 3500 new streetlights were installed. While residents felt safer, the principal conclusion was ". . . that no evidence could be found to support the hypothesis that improved street lighting reduces reported crime."

And what about the criminal's perspective? The Home Office Crime Prevention Unit in London interviewed over 300 experienced burglars and robbers about what influenced their decision to commit a crime . Opportunity, proximity and "the excitement of risk taking" were the reasons given. Even the presence of neighbours and the possibility of intervention by passers-by were routinely considered in their decisions. However, the presence of potential witness wasn't a deterrent since the perpetrators knew witnesses would commonly take no notice or, if they did, no action. It was clear, too, that offenders were not necessarily influenced by lighting conditions. The only truly powerful deterrents cited were signs of occupancy and to a lesser extent, dogs and alarms.

"Security" Lighting

Lighting supposedly militates against crime because it enhances surveillance. Lighting that draws attention to would-be crimes might be a deterrent, as long as there are potential witnesses. Motion-sensor activated lights, with a short duration, will do this much better than lights that are left on constantly (this is the same logic as the common auto alarm-it turns on to call our attention to a potential problem and to startle the would-be criminal). However, lighting, accompanied by public vigilance (i.e. looking out for your neighbours) and greater police presence may be more effective.

Concern for property and personal safety is a natural outcome of the society that we live in. While crime rates are generally dropping, we do need to be aware of the possibility that "it could happen to me." For many people at night, the fear for personal safety is entwined with another fear, that of darkness. These two separate concerns are so often treated as a single item, that it can be tough to imagine them apart. The fear of darkness is something we have lived with since we were small children wondering what or who was lurking under the bed or in the closet. This irrational fear of the dark distorts our legitimate concerns about personal safety - to the point that a brighter light is falsely viewed as making an area safer than a dimmer one could.

A whole industry has sprung up around "security" lighting, feeding on the public's fear of darkness, foisting poorly designed, glare-prone, overly bright light fixtures on a public that has blended its justifiable concern for property and personal safety with a misplaced fear of darkness. Feelings about darkness are so entrenched that the words "security lighting" are accepted unquestionably as a positive description of these light fixtures. Yet, think about the very similar "security blanket." This conjures up images of youngsters with a misplaced faith in the protective properties of their favourite "blanky" or Charles Shulz's famous Peanuts' character, Linus, and his indispensable fabric. Remember laughing at the trouble Linus' "security blanket" got him into with the rambunctious Snoopy? Charles Shulz loved to remind us of the difference between belief and actuality with these antics.

"Security" lighting is primarily about making the purchasers feel better - not necessarily improving their odds with criminals. For these reasons, the design of "security" lights involves the use of glary bulbs - people need to see the light bulb in order for it to make them feel safer. Not BE safer, but FEEL safer. If the bulb was hidden and unobtrusive (as it would be in a responsibly designed light fixture) and of a much lower brightness than what are provided with most "security" lights, it would provide better illumination. It would do so by not forcing our pupils to constrict and by not creating strong contrasts in the amount of light in one part of the yard to another. Responsible illumination can enhance surveillance - which does have an impact on crime and safety. Light can have an impact on crime only if someone is likely to be watching. A report by the City of Calgary Police Service cautions that too bright of a light may deter surveillance and actually aid criminal activity.

So, "security" lights do not replace human vigilance. "Security" lights can create a false sense of security, and poorly designed "security" lights can obscure criminal activity, both of which may ultimately be detrimental to a person's safety.

How to Light Responsibly For Safety

How often do you listen to or even hear a ticking clock? We tend to tune out all-night lights after a while, just like we tune out a ticking clock. Once this happens, "security" lights will not draw the attention of potential witnesses. This can be fixed motion detector lights.

Instead of dusk-to-dawn "security" lights, use motion-sensor activated lights. Motion sensor lights enhance surveillance by drawing attention to trespassers. This is the same logic as the car alarm or barking dog-the sensor turns lights on to call attention to a potential problem and to startle the intruder. Be sure to aim the sensor downward to guard only the area the lights illuminate.

Let's face it, everyone knows that motion sensor lights turn on whether someone is home or not. They simply do not fool potential criminals into thinking someone just turned on the light. The goal with these lights is to draw attention to activity, not create the illusion that someone is home.

Understanding the proper role and goal of security lighting (think task lighting) allows you to purchase the correct motion sensor model for your setting, as well as properly set its options (sensitivity, duration and aiming of both sensor and lights). We like motion sensor lights with the following features.

Be careful with too much of a good thing. Just as a car alarm works well when it comes on only occasionally, or a normally quiet dog starts barking, motion sensor lights should be set to light only when real intrusions occur. No one wants to live next to an irresponsible car owner with a hair trigger alarm that is constantly wailing, or a dog that won't shut up ("just steal the car already, and get it out of my neighbourhood. And will someone shoot that dog!?"). Similarly, motion sensor lights that turn on whenever anyone walks down the sidewalk, or drives down the street or laneway, will be more of an annoyance to your neighbours than an aid to your safety.

Remember, the purpose of the light is to draw attention and aid in illuminating what's happening. Too bright lighting that shines at your neighbours' windows will just ensure that they will never see anything ("A description of the culprit, officer? All I saw was a bright, glowing orb. No, I couldn't tell if his hair was brown, or even if he had hair."). Instead, think Block Watch; look out for your neighbour and don't take away the opportunity for them to watch out for you.