Challenges in IAQ for Indoor Spaces: A Comparison of the Reference Guideline Values of Indoor Air Pollutants from the Governments and International Institutions

Since people spend most of their time inside buildings, indoor air quality (IAQ) remains a highlighted topic to ensure in the built environment to improve public health, especially for vulnerable users. To achieve a better indoor environment quality (IEQ), some countries’ governments or regional institutions have developed and published reference guideline values of various air pollutants to prevent the IAQ from becoming adverse to occupants. Beyond guidelines by World Health Organization (WHO), in some countries, there are specific institutional requirements on the IAQ, and others integrated it into the building regulation for the built environment. This paper is based on the literature research, summarized from previously conducted works by the authors, on the chemical reference values of IAQ-related regulations and guidelines published by several Governments or related institutions from various regions around the World. Despite these efforts at standardization and legislation, many indoor air quality monitoring activities conducted in several countries still fall short of the main indications produced. By comparing the reference values of 35 pollutants, both physical and chemical ones, which are proposed in documents from 23 regions included so far, the IAQ research and prevention actions on progress in different regions should be included in monitoring plans with guidelines/reference values in their current state. The outcome of the paper is to define the current trends and suggest some perspectives on the field of interest for improving the indoor air quality of generic spaces at an international level. It becomes evident that, at the global level, IAQ represents a complex political, social, and health challenge, which still suffers from the absence of a systematic and harmonized approach. This is not a new situation; the issue was raised more than 40 years ago, and despite efforts and a pandemic, the situation has not changed.