C2-C6 Volatile organic compounds associated with traffic in the atmosphere of Ho Chi Minh City

With a population now exceeding 7 million, Ho Chi Minh City (HCMC) is the largest city of Vietnam. Concurrent with a rapidly expanding economy, urban air quality is becoming a serious problem due to traffic and industrial emissions of traffic and industries. Traffic is dominated by a fleet of around 4 million motorcycles running on gasoline. First monitoring efforts have started, but very little is known about volatile organic compound (VOC) emissions and imissions.

We present measurements of 18 C2-C6 VOC species at an urban road-side site in Ho Chi Minh City from January 2007. Measurements are conducted half-hourly using an online GC-FID/PID with preconcentrating on a Carbosieves SIII at 5°C.

This work is a start to identify and quantify organic compounds associated with the evaporative and exhaust emissions of the local fleet and to begin to understand the potential for human exposure. As expected , the VOC levels are generally very high during the hours of strong traffic activity. Most abundant species are trans-2-butene, cis-2-pentene, n-pentane and iso-pentane, regularly exceeding 100 ppbv during the peak hours. Due to the availability of traffic counts and the unique situation of the specific site (heavy traffic is banned during certain hours) an quantitative attribution to different vehicle types is possible.