A table comparing how much protection one gets from wearing a N95 compared to other masks. N95s that aren't fit tested provide the wearer much more protection than a surgical mask.
Note: Some health care workers are fit-tested for their N95s; the broader public is not. The University of Minnesota says "these numbers are not bright lines between safe and unsafe," the baseline time of 15 minutes for no mask wearing "is not based on any science," and "this table illustrates only the impact of time."
Source: Center for Infectious Disease Research and Policy, University of Minnesota