1U.S. Army Research Institute of Environmental Medicine, Natick, MA; and 2Boston Athletic Association, Boston, MA.
Med Sci Sports Exerc. 2015 Sep;47(9):1958-64. doi: 10.1249/MSS.0000000000000624.
The location of the wet bulb globe temperature (WBGT) index measurement may affect heat stress flag category classification.
This study aimed to compare WBGT measurements at three locations along the Boston Marathon race course and compare WBGT estimates for meteorological stations and 72-h advanced WBGT forecasts.
WBGT was measured hourly from 1000 to 1400 h at approximately 7 km, approximately 18 km, and approximately 30 km on the Boston Marathon race course. Simultaneous WBGT estimates were made for two meteorological stations southeast of the course via a commercial online system, which also provided 72-h advanced forecasts.
The measurement difference (mean ± SD) among course locations was 0.2°C ± 1.8°C WBGT (ANOVA, P > 0.05). The difference between course and stations was 1.9°C ± 2.4°C WBGT (t-test, P < 0.05). Station values underestimated (n = 98) or overestimated (n = 13) course values by >3°C WBGT (>0.5 flag category) in 111 of 245 paired comparisons (45%). Higher black globe and lower wet bulb temperatures explained over- and underestimates, respectively. Significant underestimates of WBGT resulted in misclassification of green (labeled white) and black (labeled red) course flag categories (χ2, P < 0.05). Forecast data significantly underestimated red (labeled amber) and black (labeled red) course flag categories.
Differences in WBGT index along 23 km of the Boston Marathon race route can be small enough to warrant single measurements. However, significant misclassification of flag categories occurred using WBGT estimates for meteorological stations; thus, local measurements are preferred. If the relation between station WBGT forecasts and the race sites can be established, the forecast WBGT values could be corrected to give advanced warning of approximate flag conditions. Similar work is proposed for other venues to improve heat stress monitoring.
湿球黑球温度（WBGT）指数测量的位置可能会影响热应激标志类别分类。
本研究旨在比较波士顿马拉松赛道三个位置的 WBGT 测量值，并比较气象站的 WBGT 估计值和 72 小时的高级 WBGT 预测值。
在波士顿马拉松赛道上，大约在 7 公里、18 公里和约 30 公里处，每小时测量一次 WBGT，时间从 1000 到 1400 小时。通过商业在线系统对赛道东南两个气象站进行了同时的 WBGT 估计，该系统还提供了 72 小时的高级预测。
赛道位置之间的测量差异（均值±SD）为 0.2°C±1.8°C WBGT（方差分析，P＞0.05）。赛道和站点之间的差异为 1.9°C±2.4°C WBGT（t 检验，P＜0.05）。在 245 次配对比较中，有 111 次（45%）站点值高估或低估了赛道值（n=98），差值＞3°C WBGT（＞0.5 标志类别）（n=13）。较高的黑球温度和较低的湿球温度分别解释了高估和低估。WBGT 的显著低估导致了绿色（标记为白色）和黑色（标记为红色）赛道标志类别的错误分类（χ2，P＜0.05）。预测数据显著低估了红色（标记为琥珀色）和黑色（标记为红色）赛道标志类别。
在 23 公里的波士顿马拉松赛道上，WBGT 指数的差异可能足够小，可以只进行单次测量。然而，使用气象站的 WBGT 估计值会导致标志类别分类错误；因此，首选本地测量。如果可以建立气象站 WBGT 预测值与比赛场地之间的关系，那么可以对预测的 WBGT 值进行修正，以提前警告大致的标志情况。建议在其他场地进行类似的工作，以改进热应激监测。
