Fig. 2

Illustration of regression results using 6 criteria pollutants, examining all-cause (left panel) and cardiopulmonary (right panel) mortality. Hazard ratios (and 95% CIs) were estimated using models that adjusted for age, sex, race-ethnicity, marital status, inflation-adjusted household income, education, smoking status, BMI, U.S. Census region, urban versus rural designation, and survey year. Hazard ratios are represented with circles when estimated using basic proportional hazards regressions, and with squares when estimated using complex proportional hazards (PH) regressions. Data used to generate plot are listed in Additional file 1 Table S1.