P-488 EFFECTS OF INTERNAL FACEPIECE PRESSURE SETTINGS TRIGGERING THE FAN OPERATION OF POWERED AIR PURIFYING RESPIRATORS (PART 2)—EFFECTS ON SUBJECTIVE SYMPTOMS

<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Introduction</jats:title> <jats:p>Our previous study found that humidity within a facepiece affects the feeling of stuffiness when respiratory protective equipment is worn. It was suggested that using powered air-purifying respirators (PAPRs), which provide air within the facepiece, alleviates this stuffiness. The present study investigates the relationship between the pressure settings triggering the operation of PAPRs and subjective symptoms.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>The study involved 12 healthy, non-smoking men. We prepared three types of PAPR (i.e, PAPR-A: a respirator with a pressure setting higher than that commercially adopted, PAPR-B: a respirator having a commercial setting, and PAPR-C: a respirator having no operational fan). To mitigate order effects and exercise-induced fatigue, participants were randomly assigned to six groups. Subjective symptoms during exercise were measured using the visual analogue scale (VAS). The study was approved by the Ethics Committee of UOEH.</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>The mean VAS values for intra-facepiece stuffiness were 4.67 (PAPR-A), 4.75 (PAPR-B), and 6.58 (PAPR-C). Significant differences were observed in the feeling of stuffiness within the facepiece between PAPR-A and PAPR-C and between PAPR-B and PAPR-C but not between PAPR-A and PAPR-B. Similar results were obtained for other subjective symptoms, namely difficulty in breathing, hotness within the facepiece, and discomfort.</jats:p> </jats:sec> <jats:sec> <jats:title>Discussion</jats:title> <jats:p>Considering our other finding that the intra-facepiece carbon dioxide concentration improved with enhanced ventilation, the observed improvements in subjective symptoms are also attributed to this enhancement. The improvement in subjective symptoms is thought to contribute to workers’ willingness to wear appropriate protective equipment.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusion</jats:title> <jats:p>Increasing the internal facepiece pressure setting of the PAPR improved subjective symptoms.</jats:p> </jats:sec>