A respirator’s filtration performance depends on 2 main factors: the filter material’s filtration efficiency and the respirator’s proper fit, meaning it forms a seal to a wear’s face around the wearer’s nose and mouth, preventing any air leakage around the edges. The seal ensures that the inhaled and exhaled air always goes through the respirator’s filter media to protect the wearer as well others around.
It is recommended by CDC NIOSH that each user performs a seal check every single time. If the respirator is too loose and you do not have an adjustable extender, improvise and try whatever you have on hand: paper clips, strings, zip ties, twines. Don’t stop until you achieve a proper fit.