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.

本研究采用移动设备开展二氧化碳（CO₂）浓度监测，旨在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CO₂记录仪（Pocket CO2 Logger），要求其全程佩戴，平均佩戴时长为8天。受试者需随时记录自身所处场所，涵盖影院、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、高校、商铺、公共交通场所及工作场所等类别。本研究采用广义线性混合模型（generalized linear mixed model）进行统计分析，以CO₂浓度的对数值作为因变量；以受试者编号作为随机效应、场所类别作为固定效应开展分析。本次研究共收集7名男性、4名女性受试者的数据，总计得到12253条有效记录。统计分析结果显示，有三类通风条件较差的场所（CO₂浓度中位数＞1000ppm）对CO₂浓度存在显著影响（p＜0.0001），分别为住宅（1316ppm）、礼堂（1173ppm）及健身房（1005ppm）。与之相对，另有两类场所虽CO₂浓度平均值较低（＜1000ppm），但对CO₂浓度存在显著影响（p＜0.0001），分别为工作场所（705ppm）及商铺（620ppm）。这款口袋式CO₂记录仪可实现不同场所空气传播感染风险的可视化，为传染病防控政策制定提供参考依据，例如人员流动管控、通风措施及相关指南的制定。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，进一步提升数据采集的便捷性与准确性。