A breathing apparatus according to embodiments of the invention includes a facemask portion sized to cover a lower portion of a wearer's face. The facemask portion includes a flow chamber. The flow chamber includes a first opening disposed near a first end of the flow chamber, a second opening disposed near a second end of the flow chamber, and a serpentine passage disposed between the first opening and the second opening. At least one light emitting diode configured to emit light having a peak wavelength in the ultraviolet range is disposed in the serpentine passage. The at least one light emitting diode is disposed off center relative to a centerline oriented along a direction of air flow through the serpentine passage.
