Figure 1.

Data collection strategy. Four sampling episodes occur at each participant home. Two sampling episodes occur during the pre-intervention winter, and two sampling episodes occur during the post-intervention winter. The implementation of household interventions (i.e., air filter, new wood stove, or placebo filter) occurs during the summer or fall between the two winters. Each sampling episode, illustrated in the table surrounded by the dashed line box, includes data collection for both health outcomes and exposure assessment. The dashed arrow for the pediatric asthma quality of life survey indicates that the data reflect the child’s symptoms, limitations and other quality of life indicators during the week prior to the corresponding home visit. Solid lines indicate periods during which data are collected on a continuous basis. Solid dots indicate measures that are assessed at specific time points (e.g., mornings for biological sample collections or mornings and evenings for pulmonary function measures).