Age

An Equal-Life literature review identified critical development periods when combined physical, internal and social exposures have significant effects on a child's development and future health.

Based on this, we developed a framework for a child’s perspective of the exposome, identifying the following age-ranges: prenatal, 0-3 years, 4-6 years, 7-12 years, 12-16 years, 16-21 years

Key Equal Life findings on “Age”

The neighbourhood and age

Children of different age groups have distinct activity patterns. Older children are more independent and roam more widely, while younger children tend to be more home-centred.

Density and layout of urban neighbourhoods greatly affect children’s social interactions outside the home, including their interactions with peers and older generations, and access to green spaces.

Access to green space is important for adolescents, and our studies found barriers to access to urban green spaces for this age group.

The prenatal period

Prenatal and early life exposure to harmful substances, such as tobacco, air pollutants, chemicals, metals combined with social factors and aspects of the internal exposome (e.g., birth weight, duration of breastfeeding, preterm birth, biomarkers, genetic variations) was associated with later cognitive impairments.

School settings and age

Auditory selective attention improves with age. Younger children (aged 6-7) face higher listening challenges in noisy classrooms and find being in noisy environments more tiring than older children (aged 8-10) do.

Classroom noise levels often exceed recommended limits, impeding children’s speech comprehension and increasing their listening effort, even a small 3 dB noise increase reduces speech in noise perception accuracy by 4–7%.

Biomarkers and age

Mid-adolescence exposures related to lifestyle, indoor environmental quality, natural environment, and family environment were associated with proteomic biomarkers of mental health, with further research needed to establish a cause-and-effect relationship.

Call to action for researchers

Call to action for educational professionals

Improve classroom acoustics by finding ways to reduce noise levels in classrooms, to no more than 55 dB(A) for silent work and to below 67 dB(A) for group work.

Noise assessments should include psychoacoustic metrics like loudness (perceived intensity) and sharpness to better reflect auditory perception in classrooms, and use child-sized artificial head microphones to account for children’s smaller ear canals and head sizes.

Call to action for healthcare professionals

Early childhood interventions should include a focus on parental’ health and stress.

CTnetwork

In future studies, apply the Equal-Life conceptual framework to larger study samples to understand how the exposome interacts with life course susceptibility from pre-natal to late adolescence.

More research is needed in understudied age groups under 7, and focusing on exposure levels and social economic status.

Further studies into the mediating role of stress between different exposures and mental health and cognitive development are needed, in particular for the age groups under 7 years.

A global, cultural and rural/urban perspective on exposure, its distribution and timing, and societal support are also needed to advance the exposome field.