Facial cooling while using respiratory protective devices in the cold.

The use of respiratory protective devices (RPDs) is essential in various work environments, including those with dust generation. When the work environment is cold, the low ambient temperature can accentuate discomfort from cooling and may influence workers' selection of RPDs, potentially affecting protective efficiency. This study aimed to quantify facial cooling while wearing particle-filtering facepiece respirators in cold conditions. Six different RPDs were selected: two filtering facepiece respirators (FFRs), two powered air-purifying respirators with constant airflow (PAPRC) and two breath-responsive air-supplied respirators (PAPRBR). Ten volunteers (six males and four females) participated, using the RPDs during rest and exercise for 40 min at an ambient temperature of -20 °C. Skin temperatures on four areas of the face and the air temperature inside the mask were recorded throughout the test. In addition, accumulated moisture in the facepiece was measured. The mean face skin temperature (MFST) was calculated as the average of the four skin temperatures. The results showed that MFST declined, on average, to 12.9 °C, 17.7 °C and 21.8 °C when PAPRC, PAPRBR and FFR were used, respectively. In conclusion, the use of RPDs in cold conditions presents particular occupational health and safety risks. Moisture retention is high when RPDs are used in cold conditions, and accumulated moisture inside the facepiece may cause discomfort and impair visibility. PAPRC decreases facial skin temperatures to an uncomfortable level, while PAPRBR and FFRs reduce cooling in cold environments. However, the required level of protection should be prioritised, even in cold conditions.