Personal protective equipment increases inhalation exposure to skin-emitted bio-effluents

Abstract

Personal protective equipment (PPE) restricts the dilution of skin-emitted bio-effluents, which may lead to pollutant accumulation in the breathing zone and thus intensify inhalation exposure of the wearer. This study quantifies the inhalation exposure risk caused by skin-emitted bio-effluents under PPE using ethyl acetate as a tracer combined with a mannequin method. The distributions of thermal-fluid parameters were predicted using computational fluid dynamics. The dispersion of skin bio-effluents was visualized, and the influence of breathing organ, pulmonary ventilation rate, bio-effluent emission rate, and emission location on inhalation exposure was examined. Wearing protective clothing increased the average air temperature and air velocity in the breathing zone by 0.9 °C and 0.09 m/s, respectively, compared with conditions without PPE. The neck and cuffs served as the dominant pathways for leakage of skin-emitted bio-effluents. Protective clothing led to higher inhalation exposure to skin bio-effluents than no PPE, with nasal breathing receiving slightly higher inhalation concentrations than oral breathing. When pulmonary ventilation rate increased from 6 to 9 L/minute under a standing posture and oral breathing, the relative inhalation concentration and the relative exposure index increased by 30.6% and 17.8%, respectively. Inhalation exposure also rose sharply when emission rates exceeded 700 μg h⁻¹p⁻¹. Emission location strongly affected inhalation exposure. Bio-effluents emitted from the groin resulted in substantially higher inhalation exposure than those emitted from the armpit. These findings would enhance the scientific understanding of human-related bio-effluents and further support the rational improvement of PPE design and the effective control of human-related pollutants.