Cincinnati Children's Hospital Medical Center, Division of Biostatistics and Epidemiology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, ML 5041, Cincinnati, OH 45229, USA.
Environ Sci Process Impacts. 2013 Oct;15(11):2030-7. doi: 10.1039/c3em00377a.
Idling school buses may increase concentrations of air pollutants including fine particulate matter (PM2.5) and elemental carbon (EC) near schools. Efforts to reduce vehicle idling near schools have rarely included air sampling to objectively assess changes in concentrations of air pollutants. The objective was to determine the impact of an anti-idling campaign on outdoor air quality at four schools with varying exposure to bus and automobile traffic. Outdoor air sampling for PM2.5, EC and particle number concentration (PNC) was conducted at four schools for five days before and after an anti-idling campaign. Sampling began before the morning arrival of buses and concluded after their afternoon departure. Sampling was simultaneously conducted at four corresponding community sites. Differences in PM2.5, EC, and PNC measured at school and community sites for each sampling day were calculated before and after the campaign. Before the campaign, the average outdoor concentration of PM2.5 during the school day at three of the four schools exceeded community background levels and the difference was greatest (4.11 μg m(-3), p < 0.01) at the school with the most buses (n = 39). The largest difference in EC between school and community sites was also observed at the school with the greatest number of buses (0.40 μg m(-3), p < 0.01). Following the anti-idling campaign, the average difference in PM2.5 at the school with the most buses decreased from 4.11 μg m(-3) to 0.99 μg m(-3) (p < 0.05). Similarly, at this school, the difference in the EC level decreased from 0.40 μg m(-3) to 0.15 μg m(-3) and PNC decreased from 11,560 to 1690 particles per cm(3) (p < 0.05). The outdoor concentrations of pollutants at schools with fewer buses (n = 5-11) were not significantly reduced. The concentration of air pollutants near schools may significantly exceed community background levels, particularly in the presence of idling school buses. Anti-idling campaigns are effective in reducing PM2.5, EC and PNC at schools with significant amounts of buses and passenger cars.
闲置的校车可能会增加学校附近空气中污染物的浓度，包括细颗粒物（PM2.5）和元素碳（EC）。减少学校附近车辆怠速的努力很少包括空气采样，以客观评估空气中污染物浓度的变化。本研究的目的是确定在四所学校开展反怠速活动对不同交通流量的校车和汽车的室外空气质量的影响。在反怠速活动前后五天，在四所学校进行了室外 PM2.5、EC 和颗粒数浓度（PNC）的空气采样。采样在早高峰校车到达之前开始，在下午离开之后结束。同时在四个相应的社区地点进行采样。在活动前后，对每个采样日在学校和社区地点测量的 PM2.5、EC 和 PNC 进行计算。在活动之前，四所学校中有三所学校在上学日的室外 PM2.5浓度超过了社区背景水平，其中最大的差距（4.11μg/m3，p<0.01）出现在有最多校车的学校（n=39）。在有最多校车的学校中，EC 在校车和社区之间的差异也最大（0.40μg/m3，p<0.01）。反怠速活动之后，有最多校车的学校的 PM2.5 平均差异从 4.11μg/m3 下降到 0.99μg/m3（p<0.05）。同样，在这所学校，EC 水平的差异从 0.40μg/m3 下降到 0.15μg/m3，PNC 从 11560 个/立方厘米下降到 1690 个/立方厘米（p<0.05）。在有较少校车（n=5-11）的学校，污染物的浓度没有显著降低。在有大量校车和乘用车的情况下，学校附近的空气污染物浓度可能显著超过社区背景水平。反怠速活动在减少有大量校车和乘用车的学校的 PM2.5、EC 和 PNC 方面是有效的。
