Motorcyclists have much higher exposure to black carbon compared to other commuters in traffic of Hanoi, Vietnam

Abstract Exposure to air pollutants, including black carbon (BC), during transportation is an important contribution to the total daily respiratory exposure for humans. Exposure to BC is especially relevant in crowded cities of developing countries. Specifically, in Hanoi (Vietnam), air pollution including black carbon is of concern, particularly near traffic. Despite public interest, no studies have been undertaken to understand the levels of respiratory exposure of BC to commuters in Hanoi, who predominantly use motorcyles. In this pilot study, we simultaneously measured BC concentrations using microAeth AE51 portable devices on motorcycles, and in the cabins of cars and buses. The mean BC concentration on motorcycles was 29.4 μg/m3 compared to 10.1 μg/m3 in the buses. BC concentrations were also shown to be influenced by traffic density. Measurements during peak traffic showed BC concentrations of 34.7 μg/m3 and 12.1 μg/m3 for motorcyclists and bus passengers, respectively. For non-rush hour periods (on weekdays), the corresponding BC levels were 27.7 and 8.4 μg/m3, respectively. BC levels inside of a passenger car with different ventilation modes was also examined. The concentrations of BC inside the cabin of a passenger car were 18.1 μg/m3 and 11.7 μg/m3, with the windows open and closed, respectively. It is estimated that motorcyclists are exposed to a significantly higher level of BC than users of buses and cars. Our findings are evidence for promoting the use of public transportation to protect public health in Hanoi, which may also be applicable to other cities in South-East Asia with similar traffic characteristics.