Respirator and Mask Classifications

I've been really scrounging as of late for supplies for our hospital, getting them from any vendor I possibly could. I was pretty excited the other day to score some P100 respirators from Office Depot, which I didn't even know sold them!

(Sorry, I just checked and, while I can include the link for the ones I got in case the situation changes, right now they're out of stock.)

Before ordering I wanted to be sure I was actually helping. I wondered - What does P100 even mean? Will it protect our nurses and doctors as well as an N95