The National Research Council has identified the lack of sufficient microenvironmental air pollution exposure data as a significant barrier to quantification of human exposure to air pollution. Transportation microenvironments, including pedestrian, transit bus, car, and bicycle, can be associated with higher exposure concentrations than many other microenvironments. Data are lacking that provide a systematic basis for comparing exposure concentrations in these transportation modes that account for key sources of variability, such as time of day, season, and types of location along a route such as bus stops and intersections. The objectives of this work are: to quantify and compare particulate matter (PM_2.5), CO, and O₃ exposure concentrations in selected active and passive transportation microenvironments; and to quantify the effect of season, time of day, and location with respect to variability in transportation mode exposure concentrations. Measurements were made with an instrumented backpack and were repeated for multiple days in each season to account for the effect of inter-run variability. Results include mean trends, spatial variability, and contribution to variance. Pedestrian and cycle mode exposure concentrations were approximately similar to each other and were substantially higher than for bus and car cabins for both PM_2.5 and O₃. Based on over 30 days of field measurements conducted over three seasons and for two times of day on weekdays, transportation mode and season were the largest contributors to variability in exposure for PM_2.5 and O₃, whereas location type alone and in combination with transport mode helped explain variability in CO exposures.

国家研究委员会已确定缺乏足够的微环境空气污染暴露数据，这是量化人类空气污染暴露的重要障碍。与许多其他微环境相比，包括行人，公交车，汽车和自行车在内的运输微环境的暴露浓度较高。缺少数据，无法提供系统的基础来比较这些交通运输方式中的暴露浓度，这些运输方式解释了可变性的关键来源，例如一天中的时间，季节以及沿公交车站和十字路口等路线的位置类型。这项工作的目标是：量化和比较颗粒物（PM _2.5），CO和O ₃在选定的主动和被动运输微环境中的暴露浓度；并量化季节，一天中的时间和位置对运输方式暴露浓度变化的影响。用仪器仪表背包进行测量，并在每个季节中重复进行数天，以说明跑步间差异的影响。结果包括平均趋势，空间变异性和对方差的贡献。行人和骑车模式下的暴露浓度大致相似，并且对于PM _2.5和O _3而言，其浓度都明显高于公共汽车和车厢。根据在三个季节进行的超过30天的实地测量以及在工作日的一天中的两次测量，运输方式和季节是造成PM _2.5和O ₃暴露变化最大的因素，而单独使用位置类型以及结合运输方式帮助解释了CO暴露量的变化。