Computer vision-based objective evaluation of increase in breathing resistances of respirators on human subjects

The purpose of this study was to evaluate objectively the impact of wearing respirators on breathing resistances of actual human subjects. We designed a monitor of the nasal airflow, which was composed of a full facepiece mask, a pipe for gathering nasal airflow, a monitoring line and a camera. A total of 5 normal adult volunteers were recruited in this study. Wearing the monitor, the subjects were required to sit for 1 min and walk for 1 min during wearing eight different models of respirators and without a respirator. Subsequently, the swing video of the monitoring line was collected by the camera during each breath of the subjects. The mean value of maximum swing angles of the monitoring line and the swing angle ratio were calculated through the image processing of the experimental videos. The experimental results show that the swing angle ratio during exhalation and inhalation are effective for representing exhalation resistances and inhalation resistances respectively. This is the first reported study that combines computer vision and the self-developed nasal airflow monitor to demonstrate quantitatively and objectively the exhalation resistances and inhalation resistances with the use of different respirators on actual human subjects.