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Dangerous strobing!

Thomas P. Ahern tahern at moose.uvm.edu
Sun Jun 18 20:27:53 EST 1995


Louis Veillette (synergi at CAM.ORG) wrote:
: I've recently worked with differnt kinds of srtobing, moving and pulsating
: lights for an event I did. At one point somebody fell victim of too much
: strobing. Luckily she regained consciousness after 15 minutes but it was
: enough to make us wonder just dangerous are those kind of lights to the
: public. I've posted some questions in different lighting and stagecraft
: forums on the Net but as you can see below, the results are too vague to be
: used with certainty. Could someone with sufficient knowledge about the
: brain and how it is affected help me with this problem?

: Here are the first conclusions we could come up with so far:
: @News.CAM.ORG

: 1. Strobe or any pulsating light can be very disorientating beucause the
: brain has problems deciphering all the data it receives about the position
: of the body. They should be used with cautions unless that's exactly the
: effect you're looking for.

: 2. People who are on drugs can also be negatively affected as a result of
: extreme strobing.

: 3. The response to strobing apparently is not from too much,
: rather it is from the right rate and intensity. I read a study
: about it 10 or so years ago, I can't recall much else except
: that they were definite about the problem being rate and
: intensity.

: 4. While the link to epilepsy was absolute, there
: were also problems with people who had petit mal seizures and
: certain kinds of brain damage that might otherwise not be
: noticeable.

: 5. Strobing lights are known to induce epileptic seizures at around
: 8-12 hz.  In many cases this can affect individuals who havent shown
: any previous symptoms, so a lot of common strobes dont flash at those
: frequencies.  However some of the more expensive types (like
: Intellabeams) have variable controls, and somebody could unknowingly
: set them in the 8-12 hz range which could mess a lot of people up
: in a 30000 seat arena...

: 6. In all cases a sign should be proeminently posted stating that Strobes
: are i effect or such so people can decide on their own if they want to take
: the risk.

: ALSO:
: 1. Since we're not EXACTLY (100%) sure at which frenquency/intensity or
: lenght of use strobes can affect people, I'll do more research possibly in
: alt.neurology or such and will keep you informed of anything new.

: 2. Effects from strobing can be very sudden and take people by surprise.
: For example the person that was hit when I was strobing told me that she
: thaught about looking somewhere else but didn't have the time to do so
: before falling on the ground. Also many strobes are not a directional
: source of light and tend to fill the whole room with light. So it's
: difficult to look "somewhere else". Plus strobes really have an hypnotic
: effect and can "suck" people into their effect, especially if they are on
: drugs on in a trance-like effect due to too much dancing. So these toys
: remain very dengerous to use because the effect is hard to avoid for the
: spectactors even when they can and want to do so.

: 3. I couldn't find anything regarding the law so far. I know that strobing
: for more than a defined period of time is illegal in some countries and
: possibly some states. Its not clear who would be blamed if somebody was
: hurt by too much strobing.


: So before all the last questions can be answered and surely even after,
: strobing should be used with extreme caution by the operator. They should
: make sure to have a global view of the spectators to promptly react in case
: of emergency when they use them.


: Special tahnx to,
: William Robinson
: Benjamin Hay
: Mike Shepherd (aka: The Sheepster)
: Ed Puntin
: Jaime Graham
: Mark Gebhardt
: Cameron Grainger



: Louis





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