The seal is the whole product
Filtering efficiency is measured through the filter medium. Air that leaks around the face seal has not been filtered at all, and a poor seal can reduce effective protection by an order of magnitude regardless of how good the filter is.
Qualitative and quantitative testing
- Qualitative — relies on the wearer detecting a test agent; suitable for disposable and half-mask respirators
- Quantitative — instrument-measured leak ratio; required for full-face and higher protection factors
Facial hair is a genuine blocker
Stubble at the seal line defeats a tight-fitting respirator. This is not a grooming policy debate — it is a measurable leak path. Where facial hair must be accommodated, specify a loose-fitting powered hood instead.
If the seal cannot be achieved, change the respirator type. Do not change the expectation.
Retest on a schedule and on change
Repeat fit testing at defined intervals, and immediately after significant weight change, dental work, facial surgery, or a change of respirator model. Fit is specific to the person and to the model.
Train the daily seal check
A fit test proves the model can seal on that face. A seal check proves it has sealed today. Both are necessary, and the daily check takes ten seconds.
