can you use computer duster to clean out portals

The only port I've ever seen filled with dust is the SD card slot. Usually if there is a problem with a USB port, Thunderbolt port, or HDMI port it is due to actual dirt or liquid which compressed air won't do a thing (at least in my own personal experience repairing our organization's Apple laptops). Compressed air may help to clean out the SD card slot, but make sure to keep the can of compressed air completely upright or you will end up damaging the laptop with the cold wet propellant released when the can of compressed air is tilted too much.

Personally I would not as you could accidentally blow dust into them.