Wearable Formaldehyde Dosimeter for Field-Ready Monitoring of Occupational Exposure and Indoor Air Quality via an Enhanced Hantzsch Reaction

Formaldehyde (HCHO, FA) poses critical health risks ranging from respiratory irritation to carcinogenicity. However, the existing detection strategies often fail to address the dual challenges of on-site acute toxicity monitoring and long-term cumulative exposure assessment. Here, we develop a ratiometric fluorescent sensing platform synergizing the solid-phase fluorescence internal filtering effect (SPFFE) with Hantzsch reaction chemistry, enabling three-tier FA analysis: (1) For complex matrices, SPFFE-separated gas–liquid phase detection achieves 0.03 mg/L sensitivity without pretreatment. (2) For indoor air monitor, 30 min passive sampling delivers 0.01 ppmv visual detection, correlating with WHO acute exposure limits. (3) A wearable paper-based dosimeter quantifies time-weighted average exposure (8-h detection window) through a cumulative signal. Field deployment revealed substantial spatial HCHO variations: bedrooms (0.02–0.07 ppmv), living rooms (0.09–0.12 ppmv), and study rooms (0.31–0.49 ppmv) with enclosed cabinets/drawers exceeded safety limits by 7.5–17.3×, highlighting microenvironmental risks from wood-panel emissions. Wearable dosimetry captured spatiotemporal exposure dynamics (6.3–22.5 vs 1.2–4.8 ppmv·min in high/low emission zones), demonstrating 89% peak exposures during cabinet access and >82% dose contribution from airflow-modulated panel emissions, informing activity-dependent mitigation strategies. This dual-mode system bridges critical gaps between regulatory compliance monitoring and personalized exposure tracking, particularly demonstrating utility for high-risk occupations (3.1–8.7× higher exposure than residential scenarios in decoration workers). The technology establishes a scalable framework for implementing “detect-to-protect” strategies in environmental health management.