Wang Qiuyun, Liu Lu
School of Economics, Southwestern University of Finance and Economics, P.R China.
Sustain Cities Soc. 2021 Dec;75:103350. doi: 10.1016/j.scs.2021.103350. Epub 2021 Sep 11.
The surprising spread speed of the COVID-19 pandemic creates an urgent need for investigating the transmission chain or transmission pattern of COVID-19 beyond the traditional respiratory channels. This study therefore examines whether human feces and public toilets play a critical role in the transmission of COVID-19. First, it develops a theoretical model that simulates the transmission chain of COVID-19 through public restrooms. Second, it uses stabilized epidemic data from China to empirically examine this theory, conducting an empirical estimation using a two-stage least squares (2SLS) model with appropriate instrumental variables (IVs). This study confirms that the wastewater directly promotes the transmission of COVID-19 within a city. However, the role of garbage in this transmission chain is more indirect in the sense that garbage has a complex relationship with public toilets, and it promotes the transmission of COVID-19 within a city through interaction with public toilets and, hence, human feces. These findings have very strong policy implications in the sense that if we can somehow use the ratio of public toilets as a policy instrument, then we can find a way to minimize the total number of infections in a region. As shown in this study, pushing the ratio of public toilets (against open defecation) to the local population in a city to its optimal level would help to reduce the total infection in a region.
新冠疫情惊人的传播速度使得迫切需要研究新冠病毒在传统呼吸道传播渠道之外的传播链条或传播模式。因此，本研究考察了人类粪便和公共厕所是否在新冠病毒传播中发挥关键作用。首先，构建一个理论模型来模拟新冠病毒通过公共卫生间的传播链条。其次，利用中国的稳定疫情数据对该理论进行实证检验，采用两阶段最小二乘法（2SLS）模型并结合适当的工具变量（IV）进行实证估计。本研究证实，废水直接促进了新冠病毒在城市内的传播。然而，垃圾在这一传播链条中的作用更为间接，因为垃圾与公共厕所有着复杂的关系，它通过与公共厕所进而与人类粪便的相互作用促进了新冠病毒在城市内的传播。这些发现具有很强的政策意义，即如果我们能够以某种方式将公共厕所的比例作为一项政策工具，那么我们就能找到一种方法来尽量减少一个地区的感染总数。如本研究所示，将城市中公共厕所（相对于露天排便）与当地人口的比例推至最佳水平将有助于减少一个地区的总感染数。
