Health risk assessment of indoor formaldehyde exposure across Chinese residences: Effects of building material grades

Prolonged exposure to elevated indoor formaldehyde levels poses significant health risk. This study investigates the emission characteristics of building materials, indoor environmental parameters, and their impacts on Chinese residents. Eleven representative cities across five climate zones in China were analyzed to predict indoor formaldehyde concentrations, assess population exposure doses, and evaluate cancer risks for three grades of building materials (E1, E0, and ENF). Results indicate that the average indoor formaldehyde concentrations ranged from 0.008 to 0.028 mg/m3 for ENF, 0.014-0.057 mg/m3 for E0, and 0.027-0.109 mg/m3 for E1. Formaldehyde pollution was more severe in summer than winter and higher in bedrooms than in living rooms. Due to heating policies, indoor formaldehyde concentrations in severe cold (Zone I) and cold zones (Zone II) during winter were significantly higher than those in other climate zones, with a maximum difference of 2.34 times. The lifetime cancer risk for populations exposed to E1 grade building materials ranged from 3.0 x 10-4 to 8.6 x 10-4, exceeding acceptable risk thresholds. Infants exhibited daily exposure dose over 2.8 times higher than adults. Replacing E1 grade materials with ENF grade materials across various climate zones could reduce cancer risk by 62.2-78.2 %. Adopting higher-grade building materials is a feasible and effective strategy for mitigating health risks associated with indoor formaldehyde exposure.