作为长期2强化地表水处理规则（LT2ESWTR）的一部分，美国环境保护局（USEPA）正在开发饮用水处理厂用臭氧灭活隐孢子虫的“CT”表。美国环境保护局（USEPA）讨论了本文件中常用的两个主要开发步骤。第一种是数据建模，包括用微生物失活模型拟合可用数据，以确定模型参数的值。第二步包括使用统计分析来确定不确定性因素，然后将其应用于模型计算的CT值。 需要一个安全系数主要是因为观察到灭活结果存在明显的分散性。包括5个参考文献、表格、图表。

As part of the Long-Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR), the US Environmental Protection Agency (USEPA) is in the process of developing a "CT" table for the inactivation of Cryptosporidium with ozone at drinking water treatment plants. This paper discusses the approach commonly used by the USEPA in the development of a CT table which includes two primary steps. The first is data modeling, which includes fitting available data with a microbial inactivation model to determine the value of the model parameter(s). The second step includes the use of statistical analysis to develop an uncertainty factor that would then be applied to CT values calculated by the model. The need for a safety factor is driven primarily by the observation that significant scatter in the inactivation results exists. Includes 5 references, table, figures.