Indoor Air Quality Guidelines (IAQGs)

Until recently, the quality of air inside buildings was not a major health concern, as outdoor air quality had been. Yet, in temperate climates we spend on average 85% of our time in enclosed environments, and a majority of that time in the home. Indoor air pollutants can have various different sources. In recent years, this subject has received increasing attention with, in particular, the French government’s creation of the French Indoor Air Quality Observatory (OQAI) in 2001. In 2024, it became the Indoor Environments Quality Observatory (OQEI), led jointly by ANSES and the Scientific and Technical Centre for Building (CSTB). Its mission now encompasses all factors that influence the comfort and health of occupants in indoor spaces, including air quality, dust, noise, natural and artificial light, electromagnetic fields, and thermal comfort.

Many measurement campaigns in indoor environments have thus been conducted, particularly in housing and public buildings such as schools or day-care centres, but also healthcare and medico-social facilities . To properly interpret the results from measurements of indoor air, reference values are needed that enable a comparison of the levels observed in relation to health criteria. Yet for many pollutants, there are not enough data available to allow scientists to establish reference values ​​for humans, which limits their ability to estimate the impact of indoor air pollution on the health of the population.

This led the Agency to issue an internal request in 2004 with a view to formulating indoor air quality guidelines (IAQGs).

ANSES establish different reference values, including Indoor Air Quality Guideline Values (IAQGs) based on health criteria, supported by recommendations on measurement methods. The setting of IAQGs is detailed in a new methodological guide published in 2025, and the methodological report assessing measurement methods was also updated in 2025.

For this assessment, ANSES brings together several expert panels to carry out a collective evaluation.

In the first place, when ANSES develops IAQGs, it takes into account the work by the World Health Organisation (WHO) specifically on indoor air. It carries out a critical analysis of the indoor air quality guidelines proposed by the WHO. 

Development of IAQGs is mainly based on:

• the description and analysis of the health effects associated with the pollutants via exposure to air. This involves drawing up a toxicological profile for each substance;
• the choice of critical effect and mechanism of action to be considered;
• a summary of the quality guidelines and toxicity reference values (TRVs) available in the literature;
• the proposed IAQGs that are able to be established according to the methodological guidelines published by ANSES, when deemed necessary.

In addition, the IAQGs proposed by ANSES are now accompanied by an analysis of the measurement methods available (updated in 2025), guidance on the sampling strategy and on how to place the established values into perspective, the identification of risk situations and a proposal, when available, of information enabling the health benefits associated with compliance with the IAQG to be quantified.

A dozen pollutants of interest in indoor air have been appraised by ANSES with regard to the IAQGs. ANSES's opinions and expert appraisal reports can be downloaded by clicking on the pollutants below (in French):

• Formaldehyde (PDF)
• Carbon monoxide (PDF)
• Benzene (PDF)
• Naphthalene (PDF)
• Trichloroethylene (PDF) and the addendum to the report (PDF)
• Tetrachloroethylene (PDF) and the addendum to the report (PDF)
• Particulate matter (PDF)
• Hydrocyanic acid (PDF)
• Nitrogen dioxide (PDF)
• Acrolein (PDF) (updated in 2022)
• Acetaldehyde (PDF)
• Ethylbenzene (PDF)
• Toluene (PDF)

The values proposed for these pollutants are summarised in the table that can be downloaded at the following link:

> View the summary table of published IAQGs (PDF)

Beyond proposing values for individual substances, ANSES launched, in 2016, a collective expert assessment to develop reference values for mixtures of chemical substances. Initially, an overview of existing methods for addressing mixtures in health risk assessment and in the derivation of reference values was carried out. Building on this work, ANSES applied the recommendations from the overview to develop an Indoor Air Quality Guideline Value (IAQGs) for a mixture of aldehydes, later extended to include other irritant substances present in indoor air. 

The IAQGs proposed by ANSES are the initial basis of the institutional process that seeks to establish regulatory values for the monitoring of indoor air quality. They are based solely on health criteria and are for information only.

To support the public authorities in establishing operational values to enable measures to be implemented to improve indoor air quality, the Ministry of Health asks the French High Council for Public Health (HCSP) to propose management support reference values for air in confined spaces, based on ANSES's IAQGs, along with a timetable for their deployment. The HCSP formulates proposals to inform risk managers of the concentration levels from which measures should be undertaken. In doing this, it takes account of practical, regulatory, legal, economic and sociological considerations.

Lastly, in accordance with the Act of 1 August 2008 on environmental liability, regulatory IAQGs are established by the Ministry of Ecology, included in the French Environment Code and associated with enforceable management measures. To date, indoor air quality guidelines have been defined for formaldehyde and benzene.

The monitoring of indoor air quality has been gradually implemented, initially for early childhood care facilities, nursery schools, and primary schools, and later extended to leisure centers, secondary education institutions, and vocational training facilities. Following the feedback gathered on the implementation of this monitoring, a revision of the regulatory framework was initiated as part of the 4th National Health and Environment Plan (PNSE 4).

The new indoor air quality monitoring system, in force since 1 January 2023, is structured around the following key elements (Ministry of solidarity and health, in french):

• An annual assessment of ventilation systems, now including direct-reading CO₂ measurements;
• A self-assessment of indoor air quality at least every four years;
• Continuous pollutant monitoring campaigns at certain “key stages in the building’s lifecycle”;
• An action plan.