Jones Benjamin, Sharpe Patrick, Iddon Christopher, Hathway E Abigail, Noakes Catherine J, Fitzgerald Shaun
Department of Architecture and Built Environment, University of Nottingham, Nottingham, UK.
Chartered Institution of Building Services Engineers Natural Ventilation Special Interest Group, 222 Balham High Road, London, UK.
Build Environ. 2021 Mar 15;191:107617. doi: 10.1016/j.buildenv.2021.107617. Epub 2021 Jan 19.
We present a mathematical model and a statistical framework to estimate uncertainty in the number of SARS-CoV-2 genome copies deposited in the respiratory tract of a susceptible person, , over time in a well mixed indoor space. By relating the predicted median for a reference scenario to other locations, a Relative Exposure Index (REI) is established that reduces the need to understand the infection dose probability but is nevertheless a function of space volume, viral emission rate, exposure time, occupant respiratory activity, and room ventilation. A 7 h day in a UK school classroom is used as a reference scenario because its geometry, building services, and occupancy have uniformity and are regulated. The REI is used to highlight types of indoor space, respiratory activity, ventilation provision and other factors that increase the likelihood of far field ( m) exposure. The classroom reference scenario and an 8 h day in a 20 person office both have an and so are a suitable for comparison with other scenarios. A poorly ventilated classroom (1.2 l s per person) has suggesting that ventilation should be monitored in classrooms to minimise far field aerosol exposure risk. Scenarios involving high aerobic activities or singing have ; a 1 h gym visit has a median , and the superspreading event has . Spaces with occupancy activities and exposure times comparable to those of the reference scenario must preserve the reference scenario volume flow rate as a rate to achieve , irrespective of the number of occupants present.
我们提出了一个数学模型和一个统计框架，用于估计在一个通风良好的室内空间中，随着时间推移，易感染人群呼吸道中沉积的严重急性呼吸综合征冠状病毒2（SARS-CoV-2）基因组拷贝数的不确定性。通过将参考场景中的预测中位数与其他位置相关联，建立了一个相对暴露指数（REI），该指数减少了理解感染剂量概率的需求，但仍然是空间体积、病毒排放率、暴露时间、居住者呼吸活动和房间通风的函数。英国学校教室的7小时教学日被用作参考场景，因为其几何形状、建筑设施和占用情况具有一致性且受到规范。REI用于突出增加远场（>2m）暴露可能性的室内空间类型、呼吸活动、通风条件和其他因素。教室参考场景和20人办公室的8小时工作日的REI均为[具体数值]，因此适合与其他场景进行比较。通风不良的教室（每人1.2升/秒）的REI为[具体数值]，这表明应监测教室通风情况，以将远场气溶胶暴露风险降至最低。涉及高有氧活动或唱歌的场景的REI为[具体数值]；1小时的健身房锻炼的中位数REI为[具体数值]，而超级传播事件的REI为[具体数值]。与参考场景的占用活动和暴露时间相当的空间，无论在场人数多少，都必须将参考场景的体积流量保持为[具体流量]，以实现[具体目标]。
