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Updated: Oct 16, 2025

Automated, High-resolution Mobile Collection System for the Nitrogen Isotopic Analysis of NOx
Published on: December 20, 2016
Nitrous acid (HONO) emission factors for diesel vehicles determined using a chassis dynamometer
Yoshihiro Nakashima1, Yoshinori Kondo2
1Department of Environmental and Natural Resource Science, Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8538, Japan.
Abstract:
Vehicle exhaust gases are important sources of nitrous acid (HONO). In this study, HONO in diesel vehicle exhaust was measured by incoherent broadband cavity-enhanced absorption spectroscopy using a chassis dynamometer system. The mean HONO concentrations in exhaust gases emitted by passenger cars and light-duty trucks were high when the after treatment devices were not fully working during the warming up period. The HONO/NOx ratio is a good index of HONO formation. The HONO/NOx ratios were 9.7 × 10-3-18.1 × 10-3, and were higher than what we found in a previous study. The estimated HONO emission factors were 7.71-64.70 mg (kg fuel)-1, and were lower than were found in previous studies. The results indicated that the frequency particulate matter is removed from a diesel particle filter affects the HONO concentration in the emitted gases and the HONO emission factor.
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