Brown Steven G, Vaughn David L, Roberts Paul T
a Sonoma Technology, Inc ., Petaluma , CA , USA.
J Air Waste Manag Assoc. 2017 Nov;67(11):1192-1204. doi: 10.1080/10962247.2016.1270236.
As part of two separate studies aimed to characterize ambient pollutant concentrations at schools in urban areas, we compare black carbon and particle count measurements at Adcock Elementary in Las Vegas, NV (April-June 2013), and Hunter High School in the West Valley City area of greater Salt Lake City, UT (February 2012). Both schools are in urban environments, but Adcock Elementary is next to the U.S. 95 freeway. Black carbon (BC) concentrations were 13% higher at Adcock compared to Hunter, while particle count concentrations were 60% higher. When wind speeds were low-less than 2 m/sec-both BC and particle count concentrations were significantly higher at Adcock, while concentrations at Hunter did not have as strong a variation with wind speed. When wind speeds were less than 2 m/sec, emissions from the adjacent freeway greatly affected concentrations at Adcock, regardless of wind direction. At both sites, BC and particle count concentrations peaked in the morning during commute hours. At Adcock, particle count also peaked during midday or early afternoon, when BC was low and conditions were conducive to new particle formation. While this midday peak occurred at Adcock on roughly 45% of the measured days, it occurred on only about 25% of the days at Hunter, since conditions for particle formation (higher solar radiation, lower wind speeds, lower relative humidity) were more conducive at Adcock. Thus, children attending these schools are likely to be exposed to pollution peaks during school drop-off in the morning, when BC and particle count concentrations peak, and often again during lunchtime recess when particle count peaks again.
Particle count concentrations at two schools were shown to typically be independent of BC or other pollutants. At a school in close proximity to a major freeway, particle count concentrations were high during the midday and when wind speeds were low, regardless of wind direction, showing a large area of effect from roadway emissions even when the school was not downwind of the roadway. At the second school, which sits in an urban neighborhood away from freeways, high particle counts occurred even though solar radiation was low during wintertime conditions, meaning that exposure to high particle counts can occur throughout the year.
作为旨在描述城市地区学校周围环境污染物浓度的两项独立研究的一部分，我们比较了内华达州拉斯维加斯市阿德科克小学（2013年4月至6月）和犹他州大盐湖城西部山谷市地区亨特高中（2012年2月）的黑碳和颗粒物计数测量结果。两所学校都位于城市环境中，但阿德科克小学紧邻美国95号高速公路。与亨特高中相比，阿德科克小学的黑碳（BC）浓度高13%，而颗粒物计数浓度高60%。当风速较低（小于2米/秒）时，阿德科克小学的黑碳和颗粒物计数浓度均显著更高，而亨特高中的浓度随风速变化没有那么大。当风速小于2米/秒时，无论风向如何，相邻高速公路的排放对阿德科克小学的浓度有很大影响。在两个地点，黑碳和颗粒物计数浓度在通勤时段的早晨达到峰值。在阿德科克小学，颗粒物计数在中午或下午早些时候也达到峰值，此时黑碳浓度较低且条件有利于新颗粒物形成。虽然这个中午峰值在大约45%的测量日出现在阿德科克小学，但在亨特高中仅出现在约25%的日子，因为阿德科克小学更有利于颗粒物形成的条件（更高的太阳辐射、更低的风速、更低的相对湿度）。因此，就读于这些学校的儿童可能在早晨上学时接触到污染峰值，此时黑碳和颗粒物计数浓度达到峰值，并且在午餐休息时颗粒物计数再次达到峰值时也经常接触到污染峰值。
两所学校的颗粒物计数浓度通常与黑碳或其他污染物无关。在一所紧邻主要高速公路的学校，中午和风速较低时，无论风向如何，颗粒物计数浓度都很高，表明即使学校不在道路的下风向，道路排放也有很大的影响范围。在第二所位于远离高速公路的城市社区的学校，即使在冬季太阳辐射较低的情况下，颗粒物计数也很高，这意味着全年都可能接触到高颗粒物计数。
