In-Cabin Commuter Exposure to Ultrafine Particles on Los Angeles Freeways

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• 作者：Yifang Zhu ; Arantzazu Eiguren-Fernandez ; William C. Hinds ; Antonio H. Miguel
• 刊名：Environmental Science & Technology
• 出版年：2007
• 出版时间：April 1, 2007
• 年：2007
• 卷：41
• 期：7
• 页码：2138 - 2145
• 全文大小：770K
• 年卷期：v.41,no.7(April 1, 2007)
• ISSN：1520-5851

文摘

Worldwide people are exposed to toxic ultrafine particles(UFP, with diameters (dp) less than 100 nm) and nanoparticles (NP, dp < 50 nm) under a variety of circumstances.To date, very limited information is available on humanexposure to freshly emitted UFP and NP while traveling onmajor roads and freeways. We report in-cabin andoutdoor measurements of particle number concentrationand size distributions while driving three vehicles on LosAngeles freeways. Particle number concentrations and sizedistributions were measured under different vehicleventilation settings. When the circulation fan was set toon, with substantial external air intake, outside changes inparticle counts caused corresponding in-cabin changesapproximately 30-60 s later, indicating an maximal airexchange rate of about 120-60 h^-1. Maximum in-cabinprotection (~85%) was obtained when both fan andrecirculation were on. In-cabin and outdoor particle sizedistributions in the 7.9-217 nm range were observed to bemostly bimodal, with the primary peak occurring at 10-30 nm and the secondary at 50-70 nm. The vehicle'smanufacture-installed particle filter offered an in-cabinprotection of about 50% for particles in the 7-40 nm sizerange and 20-30% for particles in the 40 to ~200 nmsize range. For an hour daily commute exposure, the in-vehicle microenvironment contributes approximately 10-50% of people's daily exposure to UFP from traffic.