Baumgardner Ralph E, Edgerton Eric S
a U.S. Environmental Protection Agency , Research Triangle Park , North Carolina , USA.
b Environmental Science & Engineering, Inc. , Durham , North Carolina , USA.
J Air Waste Manag Assoc. 1998 Aug;48(8):674-688. doi: 10.1080/10473289.1998.10463722.
A predominantly rural ozone monitoring network was operated under the auspices of the Clean Air Status and Trends Network (CASTNet) from 1988 until 1995. Ozone data from sites in the eastern United States are presented and several indices are used to describe the spatial and temporal distribution of ozone concentration and exposure. These indices are SUM06, W126, the 8-hour rolling average (MAX>80), and the current National Ambient Air Quality Standards (NAAQS) for ozone. Ozone indices were selected to illustrate the spatial and temporal distribution of ozone, and the sensitivity of this distribution to different representations of concentration or exposure. CASTNet is unique in that a uniform set of site selection criteria and uniform procedures, including traceability to a single primary standard, provide a high degree of comparability across sites. Sites were selected to avoid undue influence from point sources, area sources, or local activities. The sites reflect a wide range of land use and terrain types including agricultural and forested, in flat, rolling, and complex terrain from the eastern seaboard across the Appalachian Mountains to the Midwest. Results indicate that ozone concentrations varied greatly in time and space across the eastern United States. Sites in the upper northeast, upper midwest, and southern periphery subregions experienced relatively low ozone during the years of record compared to sites in the northeast, midwest, and south central subregions. Ozone exposures at an individual rural site are dependent on many factors, including terrain, meteorology, and distance from sources of precursors. Relative to the current (as of 1996) NAAQS, only a handful of CASTNet sites near major urban areas report exceedances. In contrast, the majority of CASTNet sites might exceed the proposed new primary standard for ozone. Sites at high elevation (>900m) in the east exhibit relatively high exposure statistics (e.g., SUM06 and W126), but no exceedance of the current ozone standard from 1988 through 1995. Terrain effects explain some of the variability within subregions and are an important consideration in the design of monitoring networks for ozone and possibly other pollutants.
1988年至1995年期间，在清洁空气状况与趋势监测网（CASTNet）的支持下，运行了一个以农村地区为主的臭氧监测网络。文中展示了美国东部各监测点的臭氧数据，并使用了几个指标来描述臭氧浓度和暴露情况的时空分布。这些指标包括SUM06、W126、8小时滚动平均值（MAX>80）以及当前的臭氧国家环境空气质量标准（NAAQS）。选择这些臭氧指标是为了说明臭氧的时空分布，以及这种分布对浓度或暴露的不同表示方式的敏感性。CASTNet的独特之处在于，一套统一的选点标准和统一的程序，包括可追溯到单一主要标准，使得各监测点之间具有高度的可比性。选点时避免了点源、面源或当地活动的不当影响。这些监测点反映了广泛的土地利用和地形类型，包括农业和森林地区，分布在从东部沿海地区穿过阿巴拉契亚山脉到中西部的平坦、起伏和复杂地形中。结果表明，美国东部的臭氧浓度在时间和空间上变化很大。与东北部、中西部和中南部次区域的监测点相比，上东北部、上中西部和南部边缘次区域的监测点在记录年份中的臭氧浓度相对较低。单个农村监测点的臭氧暴露情况取决于许多因素，包括地形、气象以及与前体物质源的距离。相对于当前（截至1996年）的NAAQS，只有少数靠近主要城市地区的CASTNet监测点报告超标。相比之下，大多数CASTNet监测点可能会超过提议的新的臭氧主要标准。东部高海拔（>900米）地区的监测点显示出相对较高的暴露统计数据（如SUM06和W126），但在1988年至1995年期间没有超过当前的臭氧标准。地形效应解释了次区域内的一些变异性，并且在设计臭氧以及可能其他污染物的监测网络时是一个重要的考虑因素。
