date YYYY/MM/DD, time HH:MM:SS, datetime, co2 ppm, temp celcius, humid %RH, Location, and Subject ID

We employed carbon dioxide (CO2) concentration monitoring using mobile devices to identify location-specific risks for airborne infection transmission. We lent a newly developed, portable Pocket CO2 Logger to 10 participants, to be carried at all times, for an average of 8 days. The participants recorded their location at any given time as cinema, gym, hall, home, hospital, other indoors, other outgoings, pub, restaurant, university, store, transportation, or workplace. Generalized linear mixed model was used for statistical analysis, with the objective variable set to the logarithm of CO2 concentration. Analysis was performed by assigning participant identification as the random effect and location as the fixed effect. The data were collected per participant (seven males, four females), resulting in a total of 12,253 records. Statistical analysis identified three relatively poorly ventilated locations (median values > 1,000 ppm) that contributed significantly (p < 0.0001) to CO2 concentrations: homes (1,316 ppm), halls (1,173 ppm), and gyms (1005ppm). In contrast, two locations were identified to contribute significantly (p < 0.0001) to CO2 concentrations but had relatively low average values (<1,000 ppm): workplaces (705 ppm) and stores (620 ppm). The Pocket CO2 Logger can be used to visualize airborne infectious transmission risk by location to help guide recommendation regarding infectious disease policies, such as restrictions on human flow and ventilation measures and guidelines. In the future, large-scale surveys are expected to utilize the global positioning system, Wi-Fi, or Bluetooth of an individual’s smartphone to improve ease and accuracy.

本研究借助移动设备开展二氧化碳（carbon dioxide, CO₂）浓度监测，以识别空气传播感染的场所特异性风险。我们向10名受试者发放了全新研发的便携式口袋式二氧化碳记录仪（Pocket CO₂ Logger），要求其全程佩戴，平均佩戴时长为8天。受试者需记录任意时刻所处的场所类型，涵盖电影院、健身房、礼堂、住宅、医院、其他室内场所、其他户外场所、酒吧、餐厅、大学、商铺、公共交通场所及工作场所。本研究采用广义线性混合模型开展统计分析，将目标变量设定为二氧化碳浓度的对数值；分析过程中以受试者编号作为随机效应，以场所类型作为固定效应。本次研究共纳入7名男性、4名女性受试者，最终累计获得12253条有效记录。统计分析结果显示，有3处通风条件相对较差的场所（中位浓度＞1000 ppm）对二氧化碳浓度存在显著影响（p＜0.0001），分别为住宅（1316 ppm）、礼堂（1173 ppm）及健身房（1005 ppm）。与之相对，另有2处场所虽对二氧化碳浓度存在显著影响（p＜0.0001），但其平均浓度相对较低（＜1000 ppm），分别为工作场所（705 ppm）与商铺（620 ppm）。该口袋式二氧化碳记录仪可用于可视化展示不同场所的空气传播感染风险，从而为传染病防控政策制定提供参考依据，例如人员流动限制、通风措施及相关指南等。未来，大规模调研有望借助受试者智能手机的全球定位系统（Global Positioning System, GPS）、Wi-Fi或蓝牙技术，以提升监测的便捷性与准确性。