Outdoor Night Time Lighting May Reduce Crime

March 8, 2018 in Health, Light, Lighting Profession

I’ve just learned about a study conducted last year for the New York City Housing Authority (NYCHA).  In a randomized trial 39 NYCHA sites received additional night-time lighting for 6 months, while 38 sites received no additional lighting.  The study showed these reductions in crimes:

Index crimes: 7% reduction in overall index crimes (day and night). This reduction in overall index crimes was driven by a 39% reduction in index crimes that took place outdoors at night.

Felony crimes: 5% reduction in overall felony crimes (day and night). This reduction in overall felony crimes was driven by a 30% reduction in felony crimes that took place outdoors at night.

Assault, homicide and weapons crimes: 2% reduction in overall assault, homicide, and weapons crimes (day and night). This reduction in overall assault, homicide and weapons crimes was driven by a 12% reduction in assault, homicide and weapons crimes that took place outdoors at night.

Misdemeanor crimes: No detectable change in net misdemeanor crimes in treatment communities.

The results of other studies have been mixed, but I’m not clear if they were controlled, randomized studies.

The disappointing thing, from a lighting designer’s perspective, is the data that’s missing.  The report tells us the fixture wattage and lumen output, but doesn’t tell us the area covered or measure the increased light levels.  Instead it treats light fixtures as fixed items and counts them per square block.  This method would be fine if the world had only one type of outdoor fixture, but it doesn’t  So more light is better, but it doesn’t say how much more or what the upper limit should be.