Cleaning Circuits with Compressed Air

You'll indeed risk building up high static voltages. Blowing air can do this easily. Think of thunderstorms when a cold front slides under the warmer air pushing it high upwards: the air-against-air movement can build up millions of volts.

In the case of the compressor your "lightning strikes" will be restricted to a few cm maximum, with energies of a few mJ, but that will be enough to destroy your CMOS parts.

IPC-A-610: Acceptability of Electronic Assemblies Section 3.1.2 mentions compressed air as a possible source of electrostatic discharge.

This forum post which claims to lay out the "Truths, myths, and flat out lies" about ESD notes that compressed air is a source of ESD due to the air rubbing against the air. But it claims that most of the charge is dissipated from the air particles before they hit the surface.

However, if you read the IPC spec, it talks about building up charge due to the air moving over insulating surfaces. So the charge will build up as it leaves the nozzle from air to air friction. Some (but not all) of that charge will dissipate as it travels to the board. But more charge will build up as the air moves across the laminate of the board itself.

The compressed air will defiantly have some charge as it leaves the can and it will build up more charge as is blows across the board. Whether or not the amount of charge is enough to damage your parts depends on a lot of factors. But it is very possible. When in doubt, test it.

I really don't think that clean, dry air can carry a charge or cause ESD. After all, ionized air is often used to reduce ESD risks.

However, if there are any particles or droplets at all in rapidly moving air, these can easily transport charge from one place or another, acting just like the belt in a Van de Graaff generator. It's the raindrops in a thunderstorm that create lightning, and I have gotten some surprising jolts from the plastic hose of my shop-vac when cleaning up large quantities of sawdust.

That said, I still think that "cleanliness is next to Godliness" with electronics, and the consequences of leaving dust in equipment are far worse than the risks of removing it. Dust inhibits the transfer of heat, and dust+humidity can develop into conductive surface contamination that can be very hard to remove later. I regularly clean dust out of gear using both a vacuum cleaner and/or compressed air.