I would also add that the mask should be fit-tested and the straps should be inspected. If the straps start to wear out, you will lose your seal, which usually happens after 2-3 days of use, but could be sooner if you’re donning/doffing it (ie pulling on the straps) more frequently. Also any visible soiling or staining on the mask can compromise the filter. That’s why many healthcare workers are currently wearing a loose surgical mask over their disposable n95 during this COVID-19 pandemic. It helps keep splashes of blood, urine, feces, etc from landing on the mask and compromising the filtration.