Aloha,
If you don't have easy access to compressed air, use a vacuum attachment and suck out the dust.

Put your hands around it so all the suction is concentrated on the hole.
If that doesn't satisfy...Sure it's safe to take it apart, if it's unplugged, of course.

Opening it up can sometimes reveal potential problems like a bad connection that has been arcing and burning/overheating. I do it all the time. I just fixed a 3x150W MH light for a friend. A problem with a connection in the ballast housing had caused it to short out and start smoking. I replaced a few melted wires and connections and now it works as good as new. I also left the ends off of the ballast box so it runs much cooler, extending the life of the unit.
my 2 cents,
Mark

808-345-1049
Edited by Mark Peterson - July 20 2013 at 12:04pm