Simultaneous measurements of on-road/in-vehicle nanoparticles and NOx while driving: Actual situations, passenger exposure and secondary formations

• Published in: The Science of the total environment Vol. 563-564; pp. 944 - 955
• Main Authors: Yamada, Hiroyuki, Hayashi, Rumiko, Tonokura, Kenichi
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.09.2016
• Subjects: Air Pollution - analysis; Automobiles; Environmental Monitoring - instrumentation; Environmental Monitoring - methods; In-vehicle air quality; Japan; Nanoparticles - analysis; Nitrogen Oxides - analysis; NOx; On-road air quality; Particle number concentrations; Particle Size; Secondary formed pollutant; Vehicle Emissions - analysis; In-vehicle air quality; Particle number concentrations; On-road air quality; NOx; Secondary formed pollutant; NO(x)
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2015.11.093

Simultaneous measurements of on-road and in-vehicle NO and NO2 levels, particle number concentrations (PNCs), and particles size distributions were performed while driving using a test vehicle equipped with real-time sensors. The results obtained on regional roads showed that heavy-duty vehicles in traffic seem to have a major impact on on-road air quality. Measurements on highways that included a 10km tunnel and a 2km uphill section of road indicated that sub-50nm particles have different features from the other species because of their higher volatility. The other species showed quite high on-road concentrations in the tunnel. In-vehicle conditions were made similar to the on-road ones by setting the air conditioning (AC) mode to the fresh air mode. The in-vehicle NO2 concentration in the tunnel was over 0.50ppmV, which is almost five times higher than the 1-hour ambient air quality standard proposed by the World Health Organization (WHO). In sections other than the tunnel, the in-vehicle NO2 concentration was almost the same as the 1-hour WHO standard. Higher on-road NO2/NOx ratios than those of exhaust gases and different behavior of sub-50nm particles from other species suggested that NO2 and sub-50nm particles were mainly due to secondary products formed by atmospheric reactions. [Display omitted] •On-road / In-vehicle air qualities were monitored simultaneously during driving.•PNCs, particle size distributions, NO and NO2 were measured.•Air qualities seem to have a relation to levels of heavy duty traffic.•On-road concentrations of NO2 and PNCs with particle sizes over 50 nm were quite high in the long tunnel.•In-vehicle NO2 often exceeds the 1-hour WHO standard with fresh air AC mode.