Background

Mounting evidence links exposure to traffic-related air pollution (TRAP) to impairment in cognitive functioning.

Objectives

To determine if short-term, controlled exposure to diesel exhaust (DE) adversely affects one or more cognitive function domains.

Methods

We carried out a double-blinded crossover design with 28 healthy, adult volunteers. Volunteers were exposed to two conditions for 120 min each, on separate order-randomized occasions: filtered air (FA) and DE (300 µg/m³ PM_2.5) at the Air Pollution Exposure Laboratory (APEL) at Vancouver General Hospital (VGH). Volunteers were blinded to the two exposure conditions. Volunteers completed five computerised neuropsychological tests of the Cambridge Neuropsychological Test Automated Battery (CANTAB) prior to (2-hr before) and at three timepoints following each exposure condition (0-hr, 3-h post-, and 24-h post-exposure). The selected CANTAB tests were related to five cognitive domains – attention, spatial working memory, strategy use, executive function, and processing speed. We hypothesized that short-term diesel exposure would adversely affect one or more cognitive function domains.

Results

Following screening, 15 volunteers were randomized to receive FA followed by DE and 14 volunteers were randomized to receive the exposures in the reverse sequence. A total of 28 volunteers contributed to the final analysis. Short-term exposure to DE was associated with slower reaction times in the Reaction Time Index task. DE was associated with a decrease of 18.2 ms (p = 0.05) in simple reaction time and 23.5 ms (p = 0.04) in five-choice reaction time.

Conclusions

This first study to investigate the effects of TRAP on the cognitive performance of humans in a controlled environment shows slowed reaction times similar to those previously demonstrated with blood alcohol levels of 0.05%. Important implications exist for workers in occupations where attention and reaction time are connected to safety and performance.

中文翻译：

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吸入柴油机尾气对人类志愿者认知能力的影响： 一项随机对照交叉研究

 背景

越来越多的证据表明，暴露于与交通相关的空气污染 （TRAP） 与认知功能受损有关。

 目标

确定短期、受控地暴露于柴油机尾气 （DE） 是否会对一个或多个认知功能领域产生不利影响。

 方法

我们与 28 名健康的成年志愿者进行了双盲交叉设计。志愿者在不同的顺序随机场合暴露在两种条件下，每次 120 分钟：在温哥华总医院 （VGH） 的空气污染暴露实验室 （APEL） 过滤空气 （FA） 和 DE （300 μg/m³ PM_2.5）。志愿者对这两种暴露条件不知情。志愿者在之前（2 小时前）和每种暴露条件之后的三个时间点（暴露后 0 小时、3 小时和暴露后 24 小时）完成了剑桥神经心理学测试自动电池 （CANTAB） 的五次计算机化神经心理学测试。选定的 CANTAB 测试与五个认知领域相关——注意力、空间工作记忆、策略使用、执行功能和处理速度。我们假设短期接触柴油会对一个或多个认知功能领域产生不利影响。

 结果

筛选后，15 名志愿者被随机分配接受 FA，然后是 DE，14 名志愿者被随机分配接受相反序列的暴露。共有 28 名志愿者为最终分析做出了贡献。在反应时间指数任务中，短期暴露于 DE 与较慢的反应时间有关。DE 与简单反应时间减少 18.2 ms （p = 0.05） 和五选反应时间减少 23.5 ms （p = 0.04） 相关。

 结论

这项调查 TRAP 对受控环境中人类认知能力影响的第一项研究显示，反应时间减慢与之前血液酒精含量为 0.05% 时所证明的反应时间相似。对于注意力和反应时间与安全和绩效相关的职业中的工人来说，存在重要影响。