Figure 2.

Percent Changes (95% CI) in semen quality parameters associated with a 10 μg/m³ increase in O₃ in Chinese adult men. Abbreviation: O₃ = ozone. Models were adjusted for age (<33 versus ≥33 years), BMI (<24.0, 24.0–28.0, > 28.0 kg/m²), ever having fathered a child (yes versus no), education (below college or university, and college or university above), smoking status (no versus yes), household income (≤5000, 5001–10 000, ≥ 10 001 RMB), daily ambient temperature using a natural cubic spline with 3 degrees of freedom, and abstinence time (<4 versus ≥4 days).