Nitrogen Dioxide and Respiratory Illness in Children. Part III: Quality Assurance in an Epidemiologic Study

This report describes the quality assurance and quality control program developed for the previously reported epidemiologic study of nitrogen dioxide (NO₂) and respiratory illness in children (Health Effects Institute Research Report 58, Parts I and II). The specific aims of the program were to make certain that data were sufficiently accurate, complete, verifiable, and retrievable. The quality assurance and quality control program consisted of: a written protocol, standard operating procedures, written records, a project management system, appropriate data processing, data verification, and data analysis planning, and was staffed by qualified and trained personnel.