Air Particle Measurement

This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.Description: Studies have suggested that aerosol number concentrations may be better correlated to health effects than mass concentrations so that the high particle number concentrations in the vicinity of freeways raise concerns regarding adverse health effects on people living there. Thus, it is important to understand how particles transport and transform near roadways for regulatory purposes. Driven by different mixing forces, exhaust dilution near roadways usually experiences two distinct dilution stages after being emitted-'tailpipe-to-road' and 'road-to-ambient'. The first stage dilution is induced by traffic-generated turbulence and the dilution ratio usually reaches up to about 1000:1 in around 1-3s; the second stage dilution is mainly dependent on atmospheric turbulence, the additional dilution ratio is usually about 10:1, and the process usually lasts around 3-10min. The aerosol dynamical processes, such as nucleation, condensation and coagulation were qualitatively investigated in the first stage. For the second stage, condensation and dilution were the major mechanisms in altering aerosol size distribution, while coagulation and deposition play minor roles. Based on the analysis, a modeling structure for a mechanistic roadway air quality model is proposed. Our study also indicates that in order to simulate the first stage, 'in-tailpipe' measurement of aerosol size distribution and condensable material concentrations in their original phase states is necessary. The implications for dilution tunnel design are discussed.

Amazon Sales Rank: #8565226 in Books Published on: 2004-12-01 Format: HTML Binding: Digital