Mental ill health is one of Europe’s fastest-growing public health challenges. The Equal-Life project investigated how children’s physical, social and biological environments interact to influence mental health and cognitive development. Using an exposome approach, the project examined a wide range of exposures, including housing, air quality, green and blue spaces, noise, traffic, screen time, poverty, social contacts and parenting.

Objectives

Equal-Life pursued four main objectives:

1. Innovating exposure measurement
   Developing new ways to assess children’s environments both indoors and outdoors. 
2. Identifying risk and protective factors
   Determining factors associated with mental health and cognitive development. 
3. Exploring interventions
   Examining how children’s environments can be improved across different ages and settings. 
4. Developing a digital toolbox
   Creating tools to help stakeholders and the general public understand and estimate the potential effects of environmental changes on children’s health and development.

Methods

Equal-Life combined data from 11 birth cohorts and school studies involving approximately 250,000 children in seven countries, together with more than 1,000 newly collected observations. Data covered different spatial and temporal scales and considered differences related to gender, ethnicity and social vulnerability. Exposure assessment combined traditional GIS-based methods with omics approaches and new data sources. Advanced statistical methods, including machine learning, structural equation modelling and causal modelling, were used to integrate these diverse data and examine relationships between environmental exposures and child outcomes.

Key findings

The project generated several important findings:

• It developed highly detailed noise and traffic models, validated noise propagation modelling and investigated noise indicators relevant for sleep, stress and restoration. 
• Analysis of 57 indicators in 196,052 participants revealed a strong urban–rural divide and identified distinct exposome clusters shaped by socioeconomic and physical neighbourhood characteristics. 
• Children of mothers with mental illness and living in deprived neighbourhoods experience the highest risk of mental health problems.
• The research demonstrated that where children live and how they spend their time matter for their development. 
• Physical and social factors together explained more variance in mental health than either domain alone, with many effects occurring indirectly.
• Family circumstances, neighbourhood design, environmental quality and access to green and blue spaces all contributed to mental health and cognitive outcomes, although their effects varied by age, city and country. 
• Social deprivation was consistently associated with poorer mental health and delayed cognitive development, highlighting structural inequalities. 
• Access to green spaces and playgrounds, both at home and elsewhere, was associated with better mental and cognitive outcomes.
• Proteomic and metabolomic analyses identified potential links with mental health risk markers, but no robust biomarkers shared across cohorts were established. The project therefore emphasised the need for stronger evidence, while also highlighting ethical considerations and the potential risk of medicalising childhood.

Overall, Equal-Life demonstrated the importance of holistic, multi-domain and equity-sensitive approaches to improving child health. Its findings provide opportunities for prevention and policy interventions that address both environmental quality and social inequalities. Calls to action for prevention, research and policies aimed at creating healthier environments for all children.

Equal-Life Toolbox and Guidebook

The Equal-Life Toolbox and Guidebook were disseminated through training and adopted by users in 31 countries. The toolbox and guidebook remain publicly accessible online and through the European Human Exposome Network.  

RIVM role

Equal-Life ran from January 2020 to June 2025, bringing together 23 partners from 11 European countries. RIVM led the project, with Irene van Kamp as coordinator, and continues to contribute to the European Human Exposome Network and the wider evidence base on healthy environments for children. 

Funding

This project received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 874724.