Does light make people safer? Maybe. Maybe not.

One of the cool things about LED lighting is that it provides opportunities to bring some of the benefits of big, modern infrastructures to developing countries without having to actually build the big, modern (and expensive) infrastructure.

A couple of years ago, I wrote a story for ArchitecturalSSL magazine about people installing solar-powered LED streetlights in remote villages in southern Mexico. Tying these places into the larger electrical grid would have been extremely difficult. But solar LED streetlights allowed the people who lived in those places to get the night light they wanted.

Now there's similar work happening in refugee camps in Haiti, where many people displaced by the 2010 earthquake still live. The change is undoubtedly useful: LED streetlights don't have to be powered by expensive gasoline generators, they're better on the lungs than fires, and the light level is bright enough to allow people to work and live far more easily. But what about physical safety? Surprisingly, there turns out to be a decent amount of debate over whether or not the extra light actually reduces violence and makes people safer. It's an interesting case study in how "common sense" doesn't always match up with reality and how difficult it is to attribute cause and effect in complicated social environments. From at story Txchnologist:

In recent months, the lights have come on at two camps through the efforts of aid groups, the Haitian government and the particular expertise of the Solar Electric Light Fund, or SELF, a Washington, D.C.-based nonprofit that uses renewable energy to provide light and power in developing countries.

The nexus between public lighting and safety is hotly debated in Western countries.

Some studies show a decline in crime after an area is illuminated while other research has found that crime actually increases after lights are installed, though it may be because crime is more visible. These studies are of little value, however, in places with collapsed infrastructure like Haiti, which plunged into darkness after the magnitude 7.0 earthquake flattened entire neighborhoods and killed untold thousands.

The security improvements were immediate. The lights function at full power from 6 p.m. to 12 a.m. and at 50 percent between 12 a.m. and 6 a.m. Reported acts of violence, including sexual assault, declined from about six per week when the installations began in June to one or zero per week when streetlights came online in August, according to J/P HRO data provided by SELF. While it’s possible to attribute this drop to other factors – the population of the camp had declined to 23,000 by September and community-based “protection teams” have increased patrols – residents reported feeling an increased sense of security. Increased usage of the latrines also improved Sanitary conditions “significantly,” according to J/P HRO.


    1. Schneier’s stuff is really interesting Kent, thanks for pointing it out.
      I’d say, this Haitian example shows that there are a lot of variables involved in the lights/security discussion. As I noted in the piece, though, it was clearly untenable for a tent city with tens of thousands to stay in the dark. 

  1. See also: defensible space. The idea that people care about their surroundings when they have enough of it to “defend”. Is there a chance that crimes go reported more often when security lights are installed, because they feel that the security lights entitle them to a higher standard of living? 

    Living in a poor, rural area, crimes might not go reported simply because they feel nobody (their government, either local or national) care enough about them to do anything. Perhaps by reaching out to the community and giving them a mechanism to decrease crime, it also gives them the voice to ask for help.

    Can we get a link to the sociology papers or grant proposals that were written to fund these projects in the first place? If you’re going to tag a blog post with “Society” and “Science”, I think a little more editorial effort is required by your readers than a link to a news story. With the information given, this feels more like a fluff piece.

      1. I think you answered your own question. You looked at the angle, and decided that, no, these aren’t compatible with dark skies. You didn’t base your analysis on the fact that these were, in fact “lights”.

        So… by your own standards, it should be possible to design a dark sky- friendly lamp, and that the choice between man-made light and starlight is a false choice.

  2. The International Dark Sky Association has for years been advocating intelligent lighting, lighting that keeps the sky dark and addresses security concerns.  Adequate light is all that’s needed; too much light (“luminance overload,” as they call it) that is poorly directed can be a problem too.  Some of the larger cities in Arizona have dealt with the intelligent lighting/light pollution issue and left everyone happy.  Better lighting, darker skies, and lower energy costs are the result.

  3. Outside safety matters aside:

    LED lighting means you can cook, read, do piecework, etc. inside your house after dark, without the safety and health concerns of candles or kerosene.

  4. A deserted, lit street is probably just as dangerous as a deserted, unlit street. A street with lots of eyes on it (pedestrians, shopkeepers, etc.) is safer, regardless of the amount of light, because there are other people on it watching for trouble. The lights on a lit street do increase the effective radius of the eyes watching it, though. So if a street has a few people watching it, then street lights make those people more effective at watching more of the street–more bang for the buck, increasing safety, so to speak. But if you add street lights and don’t add people, then the sense of security you feel when walking down the street is a false one. (I’m paraphrasing from Jane Jacobs’
    “The Life and Death of Great American Cities”–she says it much more

    1. So being able to see an assailant a block away is the same as not being able to see an assailant until they’re feet away? Albeit anecdotal, my personal experience says I’ll take a lighted street over an unlit one any night.

  5. Reading this post, all I can think of is growing up watching old movies. In some of them, the bad man almost always stood under a street light. 

  6. Of course street lighting will make the place safer.  What benefits does darkness provide for people who want to avoid trouble?  Hide like a ninja all the time??

    1. Of course street lighting will make the place safer. What benefits does darkness provide for people who want to avoid trouble?

      Unless you want to provide blanket coverage of pseudo-daylight (for a couple of months until we run out of oil), you create pockets of shadow for the predators and night blindness for the prey.

  7. Now if we would just reforest their half of the island…
    Haiti is just so screwed that every marginal piece of good news seems like a Biblical revelation. Makes you wonder if things are ever going to really change there.

  8. maggie, one of the more interesting things i can remember reading was the ieee’s inspection of the types of generators the US installed in iraq:

    Since then, it’s always been on the back back burner: what’s the correct engineering decision for electricity in iraq?

    they’ve recently taken another look re: afghanistan

    However, I still don’t understand how the amount of money we’ve sunk in these countries…we can’t fix the human problems, the political problems, but why can’t we make the right engineering decisions and get those people the electricity they need?

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