Anti-Particulate Adhesion Efficacy of a Cosmetic Product: A Controlled In Vivo Study Using a Patented Exposure Chamber

This study validated a controlled in vivo test protocol using a patented particulate exposure chamber (Korean Patent No. 10-2020-0068941) to evaluate the anti-particulate adhesion efficacy of a cosmetic sunscreen formulation (SPF 50+, PA++++). The primary aim was methodological—to demonstrate that the chamber system can reliably detect differences in carbon black adhesion under standardised conditions. A split-site paired design was applied to 22 healthy adult females (mean age 60.3 ± 5.2 years; range 46–68 years). Carbon black particles (≤10 μm) were dispersed via a precision dual-stage pneumatic nozzle within a sealed chamber (22 ± 2 °C; 50 ± 5% RH). Between-group comparison was assessed by the Wilcoxon signed-rank test (primary) and the generalised estimating equation (GEE) model (complementary between-group comparison per institutional SOP). The treated site showed a 55.0% reduction in carbon black adhesion (treated: 4243 ± 2225 pixels; control: 9430 ± 4769 pixels, SE = 4.82, 95% CI: −64.4 to −45.6, Wald Z = −11.41, p < 0.001; Cohen’s d = 2.43). The Wilcoxon test confirmed the result independently (Z = −4.11, p < 0.001). All 22 subjects (100%) showed consistent reduction directionality (individual rates: 22.6–74.2%; mean 51.8%; median 52.3%). Bootstrap resampling (n = 10,000), outlier-exclusion, and exact sign test sensitivity analyses all confirmed robustness. These findings represent proof-of-concept methodological validation applied to a single product under accelerated exposure conditions.