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Dangerous strobing!

Louis Veillette synergi at CAM.ORG
Wed Jun 14 16:33:04 EST 1995

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:

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

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

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.

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


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