Fit-test method for respirator with sensing system

A method of fit testing comprising:

• providing a respirator;
• providing a sensor comprising a sensing element, wherein the sensing element is in removable communication with the sensor, and wherein the sensor is removably positioned substantially within an interior gas space of the respirator;
• providing a reader configured to be in wireless communication with the sensor;
• positioning the respirator over a mouth and a nose of a user while the sensor is positioned substantially within an interior gas space of the respirator;
• and
• observing respirator fit assessment data communicated from the sensor to the reader;
• and
• capturing an image of the correct fit position on the user's face once the sensor indicates a pre-determined fit assessment data value has been reached,
• wherein the sensing element is configured to sense fluid-soluble particulate matter when a liquid layer is disposed in a gap on at least a part of the surface of the sensing element, wherein a fluid ionizable particle may at least partially dissolve and may at least partially ionize in the liquid layer, resulting in a change in an electrical property between at least two electrodes of the sensing element.