Hanoi is the capital city of Vietnam and the second largest city of the country, just behind Ho Chi Minh City. During the last two decades, Hanoi developed fast and expanded steadily. Since the city acquired large parts of the surrounding provinces in 2008, Hanoi tripled its size and doubled its population. The new development aims to spread the concentrated population and economic activities to alleviate the stress caused by pollution and the decreasing quality of life of the residents. Hanoi has a very fast growing fleet of motor vehicles, at the rate of 12% - 15% annually. The fast transition from bikes to motorcycles and to cars results in a most serious environmental burden in particular on the air quality and human health. This paper overviews the air quality and pollution caused by road traffic in central Hanoi (5 old districts) and the related health outcomes due to particulate matters (PM₁₀ and PM_2.5). It uses dose-response functions to quantify the number of extra deaths resulting from traffic-related particulate matters. The results are compared with those of other studies to assess the impacts of air pollution on human health in large, crowded and fast developing cities in Southeast Asia. Assessment of the health risk caused by traffic shows that mobility in Hanoi causes a high health burden. In 2009, mobility caused 3200 extra deaths by traffic related PM₁₀. The result shows that health impacts due to air pollution are by far larger than the number of fatalities due to traffic accidents.