Blue Skies Bluer?

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• 作者：Julian D. Marshall ; Joshua S. Apte ; Jay S. Coggins ; Andrew L. Goodkind
• 刊名：Environmental Science & Technology
• 出版年：2015
• 出版时间：December 15, 2015
• 年：2015
• 卷：49
• 期：24
• 页码：13929-13936
• 全文大小：345K
• ISSN：1520-5851

文摘

The largest U.S. environmental health risk is cardiopulmonary mortality from ambient PM_2.5. The concentration鈥搑esponse (C鈥揜) for ambient PM_2.5 in the U.S. is generally assumed to be linear: from any initial baseline, a given concentration reduction would yield the same improvement in health risk. Recent evidence points to the perplexing possibility that the PM_2.5 C鈥揜 for cardiopulmonary mortality and some other major endpoints might be supralinear: a given concentration reduction would yield greater improvements in health risk as the initial baseline becomes cleaner. We explore the implications of supralinearity for air policy, emphasizing U.S. conditions. If C鈥揜 is supralinear, an economically efficient PM_2.5 target may be substantially more stringent than under current standards. Also, if a goal of air policy is to achieve the greatest health improvement per unit of PM_2.5 reduction, the optimal policy might call for greater emission reductions in already-clean locales鈥攎aking 鈥渂lue skies bluer鈥濃€攚hich may be at odds with environmental equity goals. Regardless of whether the C鈥揜 is linear or supralinear, the health benefits of attaining U.S. PM_2.5 levels well below the current standard would be large. For the supralinear C鈥揜 considered here, attaining the current U.S. EPA standard, 12 渭g m^鈥?, would avert only 鈭?7% (if C鈥揜 is linear: 鈭?25%) of the total annual cardiopulmonary mortality attributable to PM_2.5.