Roadside Particle Number and Size Distributions of Vehicular Ultrafine and Nanoparticle Particulate Matter Emissions

摘要

A pilot study to characterize contributions by in-service vehicles to roadside ultrafine and nanoparticle particulate matter was conducted on November 17, 2000. Simultaneous measurements were made of vehicle activity and particle number distribution, upwind and downwind of a major interstate in California. Particle concentrations and size distributions were measured continuously at a distance of 5 m from the freeway shoulder between 9:30 AM and 3:30 PM. In addition, temperature, relative humidity, solar radiation, wind speed and wind direction were continuously recorded at the sampling site. The data presented here demonstrate that the roadway is a continuous source of high numbers of ultrafine and nanoparticles. Background corrected particle concentrations for particles of diameter 6 nm to 233 nm ranged from 6x10~3 to 2.4 x 10~5 particles/cm~3 . No significant particle numbers were measured for particle diameters greater than 100 nm. Ongoing work to examine the meteorological and wind data in conjunction with traffic and particulate data will provide a better understanding of highway and traffic sources of small particles, and form a basis for estimating nanoparticle exposure.