This report describes a study to investigate the relationships among daily variations in air pollution in Ho Chi Minh City (HCMC), Vietnam, hospital admissions for acute lower respiratory infections in children under age 5, and poverty. The study was part of HEI's Public Health and Air Pollution in Asia (PAPA) program and is the first study of air quality and health to be performed in Vietnam. The team of investigators, led by Drs. Le Truong Giang, Long Ngo, and Sumi Mehta, collected daily pollutant data for PM10, sulfur dioxide, nitrogen dioxide, and ozone at multiple locations throughout the city and obtained admissions data from the two pediatric hospitals in HCMC. They then performed statistical analysis on the data using Poisson time-series and case–crossover methods.