Harmonizing indoor air quality standards across Europe: A comparative analysis framework for building material regulations and public health protection

• European IAQ regulations show critical fragmentation endangering public health • Systematic framework identifies best practices across 7 EU jurisdictions • Construction materials lack harmonized emission standards in most countries • Urgent need for EU-wide binding standards based on scientific evidence Indoor air quality (IAQ) regulation across European Union Member States exhibits significant fragmentation, creating unequal health protection for populations spending 80-90% of their time indoors. This study develops a novel three-dimensional comparative framework to systematically evaluate IAQ regulatory approaches across seven European jurisdictions, focusing on construction material emissions and sustainable building integration. We created an analytical matrix comprising nine quantitative indicators across Scientific Rigor, Implementation, and Innovation dimensions. Seven case studies were analyzed: Germany, France, Finland, Belgium, Italy, Spain, and EU-LCI framework, using standardized evaluation criteria (0-5 scale) for EU-LCI alignment, vulnerable group protection, enforcement mechanisms, and life cycle assessment integration. Significant regulatory disparities emerged, with formaldehyde limits varying 300% between countries (10 μg/m³ in France vs. 100 μg/m³ in EU-LCI). Germany achieved highest performance (43/45 points) through comprehensive scientific rigor, while France excelled in innovation (15/15 points) via mandatory emission labeling. Finland demonstrated methodological leadership with dynamic emission parameters (μg/m²·h). Southern European countries showed critical gaps, with Spain scoring lowest (3/45 points). Key weaknesses include: absence of enforcement mechanisms (71% of frameworks), exclusion of emerging pollutants, limited data transparency, and misalignment between energy efficiency mandates and IAQ protection. Results demonstrate urgent need for harmonized EU-wide IAQ standards. We recommend mandatory emission labeling combining French stringency with Finnish methodology, IAQ-LCA integration, and vulnerable population protections. For Spain, priorities include binding formaldehyde limits (<50 μg/m³) and national IAQ observatory establishment. This framework provides a replicable tool for evidence-based policy development toward healthier, sustainable indoor environments.