In a project called Wave I (2002-2003), each participant was invited to participate in the clinical portion of the study, which involved collection of blood and saliva samples. This component of the study allowed for analysis of associations between exposure to social stressors, PM10, PM2.5 and biomarkers for cardiovascular disease. Three hundred and sixty seven survey participants participated in the clinical component of the study.

Each of these participants completed a second, brief questionnaire that characterized their use of vitamin, mineral and herbal supplements, use of prescription and non-prescription medications and ongoing infection symptomatology. A fasting venous blood draw was conducted to assess blood serum markers associated with heart disease (e.g., cholesterol levels), and salivary samples were collected to assess salivary cortisol, a marker of stress.

Each biomarker participant received a feedback form providing results from actionable items analyzed from their samples (e.g., low density cholesterol levels, blood pressure) along with recommendations for actions they could take to reduce their risk of blood pressure.