Toxicology Division, Texas Commission on Environmental Quality, Austin, TX, USA.
Sci Total Environ. 2018 Dec 10;644:1547-1556. doi: 10.1016/j.scitotenv.2018.06.372. Epub 2018 Jul 13.
In 2015, the United States Environmental Protection Agency (US EPA) set the ozone National Ambient Air Quality Standards (NAAQS) at 0.070 parts per million (ppm), for an annual 4th highest daily 8-hour (h) maximum average concentration, averaged over three years, with compliance based on the monitor with the highest concentrations. Numerous epidemiological studies have evaluated associations between ozone and health effects, but how the ozone concentrations derived from those studies can be compared to the ozone NAAQS is not clear, because of the complexity of the standard. The purpose of the present work was to determine how ozone summary metrics used in key epidemiology studies compare to the metrics that comprise the ozone regulatory value. Evaluation of epidemiology studies used for quantitative risk assessment in the 2015 ozone NAAQS review demonstrated that the most commonly used summary metrics that differed from the NAAQS were: 1-h maximum or 24-h average concentrations; multiple-day averages from 2 to 30 days; and averaging of ozone concentrations across all monitors in an area and over different months of the year. Using different ozone summary metrics to calculate the ozone regulatory value in twelve US cities for 2000-2002 or 2013-2015 generated alternative ozone regulatory values that were often substantively different and that may or may not vary commensurate with the regulatory standard. Comparison of epidemiology study metrics to other countries' ozone standards or guideline levels produces similar challenges as described here for the NAAQS. In conclusion, many of the ozone concentration metrics used in epidemiology studies cannot be directly compared to the ozone NAAQS, and using simple conversion ratios adds substantial uncertainty to concentration estimates. These summary metrics must be reconciled to the regulatory value before any judgements are made as to the protectiveness of current and alternative standards based on epidemiology study results.
2015 年，美国环境保护署（EPA）将臭氧国家环境空气质量标准（NAAQS）设定为 0.070ppm，这是每年第 4 高的 8 小时（h）最高日平均浓度，三年平均值，以浓度最高的监测器为基准。许多流行病学研究评估了臭氧与健康影响之间的关联，但由于标准的复杂性，这些研究得出的臭氧浓度如何与臭氧 NAAQS 进行比较尚不清楚。本研究的目的是确定关键流行病学研究中使用的臭氧综合指标与构成臭氧监管值的指标有何不同。对用于 2015 年臭氧 NAAQS 审查定量风险评估的流行病学研究的评估表明，与 NAAQS 不同的最常用的综合指标有：1 小时最高值或 24 小时平均值；2 至 30 天的多天平均值；以及一个地区内所有监测器的臭氧浓度平均值以及一年中不同月份的平均值。在 2000-2002 年或 2013-2015 年的 12 个美国城市中，使用不同的臭氧综合指标来计算臭氧监管值会产生替代臭氧监管值，这些值通常有实质性差异，并且可能与监管标准一致，也可能不一致。将流行病学研究指标与其他国家的臭氧标准或指导水平进行比较会产生类似的挑战，正如这里针对 NAAQS 所描述的那样。总之，流行病学研究中使用的许多臭氧浓度指标不能直接与臭氧 NAAQS 进行比较，使用简单的转换比会给浓度估计增加大量不确定性。在根据流行病学研究结果对当前和替代标准的保护程度做出任何判断之前，必须将这些综合指标与监管值相协调。
