On-road and in-vehicle air qualities were monitored simultaneously using a test vehicle equipped with measurements systems. The pollutant levels measured were NO2 concentrations and particle number concentrations (PNCs). Tests were conducted on two routes: One was a regional road in which the heavy duty (HD) ratio fell at an intermediate point, and the other was a highway including a 10 km tunnel and a 2 km uphill section.  In the regional road measurements, HD vehicles had a high influence on the air quality. Thus, reducing pollutants from HD exhaust will be effective in improving road and road-side air qualities. NO2 profiles exhibited broad peaks, and PNC profiles exhibited sharp peaks. This is because the major components contributing to PNCs are volatile particles that disappear relatively fast.  Mean on-road NO2 concentrations on the highway were almost 300 ppb and increased to 1200 ppb in the 10 km tunnel. When the air conditioning mode was set to the fresh air mode, the in-vehicle concentrations became almost the same as the on-road concentrations. Switching the air conditioning to the circulation mode can prevent the penetration of pollutants into the vehicle cabin.  On-road PNCs were due to mainly volatile particles, which penetrated less than accumulation mode particles. However, in the tunnel, the ratio of accumulation mode particles increased because volatile particles disappeared due to the high temperature in the tunnel.  Our observations agreed with the data reported in previous studies.

On-road and in-vehicle concentrations of NO<sub>2</sub> and particles on a highway

248th National Meeting (2014)

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On-road and in-vehicle concentrations of NO2 and particles on a highway

On-road and in-vehicle concentrations of NO₂ and particles on a highway