Figure 3

Normalized PM concentration for the particle size range 0.3–\(1.0\,\mu \hbox {m}\) near the smart mask (a) decreases as the smart mask is switched ON, (b) is increased by the aerosol droplets generated by the smart mask itself (self-interference), and (c) decreases significantly after subtracting self-interference. (d) Typical PM concentration generated by the humidifier (representing activities such as talking, coughing, and sneezing). Comparison of (e) time-averaged density, and (f) time-averaged concentration for the two PM sensors (int: on the mask, ext: on the ground) as the mitigation module is turned ON and OFF. Plots adapted from²⁰.