The document provides an overview of air quality in Vietnam in the first half of 2016, with a focus on particulate matter levels in Hanoi and Ho Chi Minh City. In Hanoi, particulate matter (PM2.5) levels exceeded Vietnam's daily limit on 72 days and the stricter WHO guideline on 158 days. PM2.5 levels peaked in January and steadily declined over the following months. Over 100 days saw unhealthy air quality according to the Air Quality Index, with only May and June seeing moderate air quality. Overall, air quality in Hanoi was unhealthy for sensitive groups in the first quarter and moderate in the second quarter.