USC staff collected data from all study participants during morning school visits. Study participation includes the following study components:

1. Health questionnaire: used to update respiratory health records, home exposures, smoking status, physical activity, and nutritional information. 
2. Physical activity assessment: Hand-recorded activity diaries and/or step-counters (pedometers) were used to record physical movement over several days around in-school testing.
3. Breathing tests: used to measure airflows and volumes. Two types of tests were done; 1. Pulmonary function test (PFT), done by taking a deep breath in, and then “blasting” it out as quickly as possible; 2. Exhaled Nitric Oxide test (eNO), done by exhaling at a control rate into a tube.
4. Height and weight measurements: used to document annual growth and how obesity may influence respiratory health.
5. Inner cheek cells (buccal cells): cell samples used to learn about inheritable traits from parents and family. Collected from brushing the inside of cheeks.
6. Dust wipe sample: collection of house dust sample from participants’ homes to test for allergens in the home environment.