Typically it is the Par, Bar, Far & Push, sounding type of consonants that cause the most problem and without the aid of a pop filter will generate massive bottom end spikes in the vocal wave file that are very hard to get rid of once they’re recorded.
Pop filters are simply a way to disperse any large exhales of air during a vocal recording, they generally consist of a double layers of stocking type fabric over a large hoop that sits about 5cm – 10cm away from the microphone.
CAUTION!.. Don’t mistake a wind sock for a pop filter
Wind socks are usually a large cylinder of foam that is placed snugly over the diaphragm cover of a microphone and are designed to stop the sound that wind over the microphone causes when recording outside. In the studio however you will find that they reduce a lot of the valuable top frequencies needed for clarity and a good vocal sound.