Abstract

Face masks reduce the expulsion of respiratory aerosols produced during coughs and exhalations (“source control”). Factors such as the directions in which people are facing (orientation) and separation distance also affect aerosol dispersion. However, it is not clear how the combined effects of masking, orientation, and distance affect the exposure of individuals to respiratory aerosols in indoor spaces. We placed a respiratory aerosol simulator (“source”) and a breathing simulator (“recipient”) in a 3 m × 3 m chamber and measured aerosol concentrations for different combinations of masking, orientation, and separation distance. When the simulators were front-to-front during coughing, masks reduced the 15-min mean aerosol concentration at the recipient by 92% at 0.9 and 1.8 m separation. When the simulators were side-by-side, masks reduced the concentration by 81% at 0.9 m and 78% at 1.8 m. During breathing, masks reduced the aerosol concentration by 66% when front-to-front and 76% when side-by-side at 0.9 m. Similar results were seen at 1.8 m. When the simulators were unmasked, changing the orientations from front-to-front to side-by-side reduced the cough aerosol concentration by 59% at 0.9 m and 60% at 1.8 m. When both simulators were masked, changing the orientations did not significantly change the concentration at either distance during coughing or breathing. Increasing the distance between the simulators from 0.9 m to 1.8 m during coughing reduced the aerosol concentration by 25% when no masks were worn but had little effect when both simulators were masked. During breathing, when neither simulator was masked, increasing the separation reduced the concentration by 13%, which approached significance, while the change was not significant when both source and recipient were masked. Our results show that universal masking reduces exposure to respiratory aerosol particles regardless of the orientation and separation distance between the source and recipient.

 抽象的

口罩可以减少咳嗽和呼气时产生的呼吸道气溶胶的排出（“源头控制”）。人们面对的方向（方位）和间隔距离等因素也会影响气溶胶的扩散。然而，目前尚不清楚掩蔽、方向和距离的综合影响如何影响个人在室内空间中接触呼吸道气溶胶的情况。我们将呼吸气溶胶模拟器（“源”）和呼吸模拟器（“接收者”）放置在 3 m × 3 m 的室内，并测量掩蔽、方向和间隔距离的不同组合的气溶胶浓度。当模拟器在咳嗽期间从前到前时，在 0.9 和 1.8 m 的距离下，口罩将接受者处的 15 分钟平均气溶胶浓度降低了 92%。当模拟器并排放置时，面罩在 0.9 m 处将浓度降低了 81%，在 1.8 m 处将浓度降低了 78%。在呼吸过程中，面对面佩戴口罩可将气溶胶浓度降低 66%，并排佩戴时在 0.9 m 处可将气溶胶浓度降低 76%。在 1.8 m 处也看到了类似的结果。当模拟器摘下面罩时，将方向从正面改为并排，0.9 m 处的咳嗽气溶胶浓度降低了 59%，1.8 m 处的咳嗽气溶胶浓度降低了 60%。当两个模拟器都被遮蔽时，改变方向并没有显着改变咳嗽或呼吸期间任一距离的浓度。咳嗽时，将模拟器之间的距离从 0.9 m 增加到 1.8 m，在不戴口罩时，气溶胶浓度降低了 25%，但在两个模拟器都戴口罩时，效果甚微。 在呼吸过程中，当两个模拟器都没有被遮蔽时，增加间隔使浓度降低了 13%，这接近显着性，而当源和接收者都被遮蔽时，变化并不显着。我们的结果表明，无论源头和接受者之间的方向和间隔距离如何，通用掩蔽都能减少呼吸气溶胶颗粒的暴露。