Seasonal patterns of indoor environmental factors and predicted airborne phthalate concentrations in Chinese residences in individual climate zones. Panels from the top to bottom show the indoor temperature, PM_2.5 concentration, and predicted gas- (red) and particle- (blue) phase concentrations of DEHP, DnBP, and DiBP, respectively. Panels from left to right show results in SC, C, HSCW, and HSWW zones, respectively. The shaded regions represent the interquartile ranges. For DEHP, the predicted total airborne concentration is shown in grey. The dust-phase concentrations of individual phthalates are treated as constants across seasons and regions, and thus the variations in airborne concentrations are merely driven by environmental factors.