Key messages

• Harmonisation of methods and safe concentrations for indoor air pollutants
• Prioritisation of chemical pollutants
• Guidance for interpreting indoor air monitoring data
• Supporting risk managers striving towards improving air quality in indoor environments in Europe 

Overview

Indoor air quality is a growing health concern, particularly as people spend up to 90% of their time indoors, exposed to a mixture of pollutants. These substances can affect the respiratory, immune, neurological, endocrine, reproductive, and cardiovascular systems. Recognising the risks related to the exposure to different chemicals, the European Union’s Chemical Strategy for Sustainability ↗ highlights the need for stronger protection of human health and the environment from hazardous chemicals, including those commonly found in indoor environments. 

This project supports the EU chemicals policy by developing a harmonised methodology for deriving health-based guideline values for indoor air pollutants. It focuses on known indoor pollutants and chemicals prioritised under PARC’s human biomonitoring and indoor exposure activities.

Indoor air contains a complex mixtures of pollutants, including volatile and semi-volatile organic compounds (VOCs and SVOCs), such as aldehydes, hydrocarbons, glycol ethers, terpenes, and reaction products. Many of PARC’s priority chemical groups, such as phthalates, PFAS, biocides, and flame retardants, may also be present indoors. Inhalation is a significant exposure route, however, current guidelines for indoor air lack harmonisation and sufficient coverage of relevant substances.

The project will develop a common methodology for deriving guideline values based on toxicological or epidemiological evidence. These values will help assess risks and support national and European health authorities in managing indoor air pollution. 

By promoting consistency and transparency, the project aligns with the EU’s ‘One substance, one assessment ↗’ (OSOA) initiative and aims to feed data into the upcoming Common Data Platform ↗. In doing so, it advances scientific consensus and regulatory decision-making on indoor air quality in Europe.

Policy relevance

Indoor air quality is a cross-cutting policy issue with relevance across multiple regulatory frameworks. In line with the OSOA initiative, indoor air guideline values based on harmonised and standardised methodology - once integrated into the Common Data Platform - will support more coherent and transparent safety assessments of chemicals across Europe. 

The European Environmental Agency (EAA ↗) has highlighted the need for action to meet the zero pollution vision for 2050, which includes reducing air pollution to levels no longer considered harmful. This vision must also address indoor air. Sustainable, long-term efforts are needed to enable comprehensive assessment of both known and emerging indoor air pollutants. This PARC project contributes to those efforts by fostering harmonisation of indoor air quality assessments and may contribute to future efforts and initiatives towards a potential EU-wide indoor air quality policy.