I've never used an airbrush before but would like to try it as I've seen it done before and it looks very easy. I have used the aerosol sprays and yes they do spray alot of colour particles into the air :(
The only way around that is as Eileen S mentioned above to try and protect your work surface and other areas of the cake.
I also dont have an air brush, that's next on my wish list. I use the PME lustre spray. I take the cake outside on a tray table and on the turn table, I can spray and turn. I've learned from experience that alot of pearl particulas are in the air when I sprayed indoors, so lesson learned. I also use the pearl dust with a soft powder brush, that works too. You still get the dust, but its not as bad as the spray.
I bought an airbrush on ebay for 108.00 that included two brushes, and the air compressor. The system works nicely but I do have to purchase a new gun. the one that came with it i think is a cheap model. I doest soray luster dust very well and i came apart on me. but if you use the 40% off coupon from hobby lobby you can get a good gun for about 45 or 50 dollars. So guess where I am off to shop very soon!!