Lessons learned from developing the worldwide IEQ guidelines database

Indoor environmental quality (IEQ) guidelines and standards aim to ensure consistent, safe and healthy indoor spaces by providing clear benchmarks for air quality, lighting, thermal comfort and acoustics. Many countries and organizations have established their own IEQ regulations and standards or guidelines, but discrepancies in parameters, definitions, methods, and updating frequency often cause them to lag behind the latest scientific and technological advancements, potentially limiting their effectiveness. Researchers and practitioners advocate for the simplification and unification of IEQ guidelines, though risking overlooking geographical and cultural specificities. To address these challenges, and to help preserve and use current knowledge, an open database compiling worldwide IEQ guidelines was developed, ensuring equitable access to up-to-date information. The database covers four key IEQ domains, indoor air quality (IAQ), thermal comfort, acoustics, and lighting, as well as two related domains: ventilation and outdoor air quality (OAQ). Ventilation is a critical factor influencing most of the other IEQ domains, while OAQ guidelines are sometimes used in the absence of indoor-specific guidelines. Each of the six resulting tables includes both mandatory governmental regulations and voluntary guidelines, along with internationally recognized standards for broader relevance. This paper summarizes key lessons learned from database development and data collection efforts over the past five years. Practical IEQ guidelines and standards balance health and wellbeing outcomes with environmental, economic, and comfort considerations. Guidelines and standards can work best when science-based, adaptable to regional contexts, and structured with clear, measurable parameters, such as exposure limits, timeframes, and validated measurement methods. Collaboration between scientific research, technological advancements, and policy development can ensure regulations remain effective and up to date. To increase compliance and raise public awareness, the database consolidates and shares existing international guidelines and standards, supporting global alignment with best practices while accommodating resource constraints and regional specificities. • Data were collected from 48 countries, significant geographical and population-based coverages • Updates frequency varies by country, some data may be based on old knowledge • Indoor and outdoor air quality guidelines are more represented than other areas, biological safety less represented • Use of different units, averaging times, monitoring tools, etc. makes it difficult to compare • Objectives (health, comfort, productivity or environmental) are often unclear • Disparity between guidelines considering occupational vs. public health