Static Electricity is Deadly
Being in the computer repair business, I can't over state the importance of grounding the nozzle of your air source when blowing out the dust on a desktop chassis. Early in the game, I had to buy a couple of Motherboards because I did not ground the metal nozzle on my portable air compressor. Now I use a couple of alligator clip leads to ground the nozzle to the metal chassis before blowing out the dust.