Is it safe to get dust out of a PC with an air blower?

That blower is connected to your mains and its plastic nozzle could easily damage electronic components if it gets too close - which is an easy mistake waiting to happen (I know by experience ;)... same reason for not using a regular vacuum cleaner near or inside a PC.

Also note that component damage by static discharge is not always immediately or ever apparent (PC resetting or stops working when it happens) but are usually much more subtle like random crashes a few times a month or whatnot... it's a bit like network security, you can't really tell if you've been compromised or not.

I blow out every old PC with a tire shop air compressor before working on it. When I am done they always work better, and run cooler. I have never lost an optical drive this way, but then I am careful not to blow into the drive.

A vacuum with a soft bristle tool is helpful for getting hardened dust off of fan leading edges. Used in combination with the air compressor, it can reduce the total amount of dust in your workshop but catching it as it comes off the PC.

I have done this with literally hundreds of PC's and never lost a component to static, or had something fail (that wasn't already dead.)

The compressed air cans have a gas that will evaporate thoroughly without residue. )The liquid will evaporate, but it will cause water in the air to condense and freeze, so not a great idea to hold cans upside down when cleaning electronics.)

Air from a compressor will have condensation as well as possible compressor oil that can get on to your components. Unless specially equipped to filter that crap out, it probably would not be a good idea to use a compressor.

As stated, a electric blower can have static issues. If you're thinking about a gas blower, you potentially run into gas/oil residue. There won't be a lot of it by any means, but it can accumulate over time, and I wouldn't want ANY of it on my system.

I would suggest sticking with canned air, multipacks aren't THAT expensive and will last a long time.

Sure, just don't create a wind tunnel in your PC. Make sure to keep a reasonable distance back when using the air blower. There's no real reason to create a hurricane in there.