The Exceptional Events Rule (EER) of the Clean Air Act was intended to address “exceptional” air quality events but, in practice, the way the rule is employed has significant impacts on regulatory data sets that are used to understand and manage air quality. Through this rule, the Environmental Protection Agency is entangled in the politics of classification, striving to separate the unnatural from the natural and the exceptional from the common with important consequences for air quality data and regulation. If deemed exceptional, the data can be removed from the regulatory record, not only altering our understanding of air quality—and, importantly, risk and exposure—but also the management of it. By analyzing regulatory data sets, texts, and appeals, this article explores the consequences of the rule’s data exclusions. I argue that the act of producing “natural exceptions” has another unintended consequence: It inadvertently creates exceptional natures; that is, natures that despite their common occurrence are deemed rare. By repeatedly removing data, the EER changes understandings of normal or expected events and becomes a powerful tool for deregulation. Ironically, even as regulations produce exceptional natures, they are simultaneously undermined by them, leading to regular and repeated surprises, unnoticed hazards, undetected exposures, and deregulation.

清洁空气法案的异常事件规则 (EER) 旨在解决“异常”空气质量事件，但在实践中，该规则的使用方式对用于了解和管理空气质量的监管数据集有重大影响。通过这条规则，环境保护局卷入了分类政治，努力将非自然与自然、特殊与普通分开，对空气质量数据和监管产生重要影响。如果认为异常，数据可以从监管记录中删除，这不仅会改变我们对空气质量的理解——重要的是，风险和暴露——还会改变空气质量的管理。通过分析监管数据集、文本和申诉，本文探讨了规则数据排除的后果。我认为产生“自然例外”的行为还有另一个意想不到的后果：它无意中创造了例外的性质；也就是说，尽管它们很常见，但被认为是罕见的。通过反复删除数据，EER 改变了对正常或预期事件的理解，并成为放松管制的有力工具。具有讽刺意味的是，即使法规产生了特殊的性质，它们也同时被它们破坏，导致经常和反复的意外、未被注意到的危险、未被发现的暴露和放松管制。EER 改变了对正常或预期事件的理解，并成为放松管制的有力工具。具有讽刺意味的是，即使法规产生了特殊的性质，它们也同时被它们破坏，导致经常和反复的意外、未被注意到的危险、未被发现的暴露和放松管制。EER 改变了对正常或预期事件的理解，并成为放松管制的有力工具。具有讽刺意味的是，即使法规产生了特殊的性质，它们也同时被它们破坏，导致经常和反复的意外、未被注意到的危险、未被发现的暴露和放松管制。