Human behavior during close contact in a graduate student office

Abstract

Close contact is a part of daily life, and proximity is known to play a primary role in the transmission of many respiratory infections. However, there are no data on close contact parameters such as movement of the head/body and relative location, which can affect both expiration and inspiration flows. Using video cameras, we collected such data for nearly 63 000 seconds of total close contact duration in a graduate student office in Beijing, China. Each student had on average 9.6 close contacts per hour and spent 9.9% of their time participating in close contact interactions. Males made more body/head movements than females during close contact. The probability distribution of interpersonal distance follows a log‐normal distribution. The average interpersonal distance was 0.67 m. Students preferred a relative face orientation angle between 15° and 45°. When the relative face orientation angle increased, the interpersonal distance increased. Students had a high probability (73%‐97%) of maintaining their head, body, and relative position during close contact, while the probability of body/head or relative position changing from any location/angle to another is also given. These data may be used for assessment of infection risk via close contact in crowded indoor environments.

Infection Spread and High-Resolution Detection of Close Contact Behaviors

“…As motions relevant to the inhalation/exhalation flows, we considered individual head and upper body motions, human respiratory activities (e.g., coughing, sneezing, and speaking), and the features of relative position (e.g., interpersonal distance and relative face orientation) of two people. The definitions of head and body motions can be found in Zhang et al [11].…”

“…Interpersonal distance directly affects the risk of virus exposure due to inhalation and deposition, the so-called short-range airborne and large droplet routes, respectively [10]. A threshold distance of close contact less than 1.5 m to 2 m is generally accepted as risky [11][12][13]. Human respiratory activities such as breathing, talking, and coughing can generate droplets of different numbers and sizes [14][15][16][17][18].…”

“…Very little data exist on indoor close contact behaviors, especially data combining all of the factors mentioned above. Some human behaviors are difficult to accurately monitor with high temporal resolution [11,19]. Electronic sensors such as radiofrequency identification devices (RFIDs) are the most commonly used to collect human contact data.…”

“…These devices, however, can only detect close contact by taking readings of interpersonal distance every 20 s, and only one-on-one close contact can be detected [23,24]. A temporal resolution of 20 s is not sufficient, as the median value duration of a close contact is 17 s [11]. Moreover, human respiratory activities and movement of body parts (e.g., head and body) cannot be detected by this means.…”

“…Body movements impact the air flows in a room. To collect close contact data with high temporal resolution, video recordings have been used, which can be processed second-by-second [11,19]. This approach is subject to human error on the part of the video analysts, and also time-consuming.…”