Emerging evidence indicates that exposure to ambient air pollution during fetal life and early childhood may influence cardiovascular health later in childhood. A large multi-cohort analysis conducted under the Environmental Influences on Child Health Outcomes (ECHO) Program evaluated the association between early exposure to fine particulate matter (PM₂.₅) and nitrogen dioxide (NO₂) and blood pressure in children aged 5–12 years.1 The study was published in Environmental Research.
Paediatric hypertension is an increasingly recognized global public health issue, with prevalence rising substantially over the past two decades.2 Elevated blood pressure in childhood is associated with adverse long-term outcomes, including adult hypertension, cardiovascular disease, and chronic kidney disease.2,3 Given that the pathophysiological origins of adult hypertension often begin early in life, the ECHO investigators explored whether prenatal and early postnatal exposure to outdoor air pollution contributes to altered blood pressure regulation in children.1
PM₂.₅ and NO₂, primarily generated by vehicular traffic, fossil fuel combustion, and industrial activity, are well-established contributors to cardiovascular morbidity in adults.4 However, evidence regarding their effects on blood pressure during childhood has been inconsistent, often limited by small sample sizes or single-site studies. The ECHO study addressed these gaps by pooling data from multiple cohorts across the United States.
Study Design and Methods
The analysis included 4,863 children enrolled from 20 ECHO cohort sites. Residential exposure to PM₂.₅ and NO₂ was estimated for each trimester of pregnancy, the entire gestational period, and the first two years of postnatal life using validated spatiotemporal models.1 Blood pressure was measured during standardized study visits and interpreted using age-, sex-, and height-specific paediatric reference values. Blood pressure readings at or above the 90th percentile were classified as elevated.
Key Findings
Higher exposure to PM₂.₅ during prenatal life and early childhood was associated with higher mean systolic blood pressure in children between 5 and 12 years of age. The association was strongest for exposure occurring during the first trimester of pregnancy, suggesting a critical window of vulnerability during early foetal cardiovascular development.1,5 First-trimester PM₂.₅ exposure was also linked to a greater likelihood of childhood blood pressure values falling within the highest percentile.
In contrast, higher maternal exposure to NO₂ during pregnancy was associated with slightly lower blood pressure in offspring, particularly when exposure occurred during the second trimester. This inverse association was not linked to an increased risk of elevated blood pressure. The authors emphasized that this unexpected finding may reflect residual confounding or the influence of correlated environmental factors, such as traffic-related noise or neighbourhood characteristics.1,6
Clinical and Public Health Implications
These findings support the concept that prenatal and early postnatal environments play a significant role in shaping long-term cardiovascular risk. Even relatively low-level exposure to PM₂.₅ during early life may have measurable effects on childhood blood pressure, potentially increasing the risk of adult hypertension and cardiovascular disease.4,5
As noted by the study author, these results add to the growing evidence that early-life exposure to fine particulate air pollution may adversely influence cardiometabolic health trajectories. The contrasting findings related to NO₂ highlight the need for further research to clarify pollutant-specific mechanisms and the role of co-exposures during critical developmental periods6.
Conclusion
The ECHO Program study provides robust, multi-site evidence that timing of air pollution exposure—particularly during early pregnancy—may be an important determinant of childhood blood pressure. These findings underscore the importance of environmental health policies and preventive strategies aimed at reducing air pollution exposure during pregnancy and early childhood to improve long-term cardiovascular outcomes.1,5
References:
- Ni Y, et al. Prenatal and early childhood exposure to ambient air pollution and blood pressure in children: Results from the ECHO Program. Environmental Research. 2024.
- Flynn JT, et al. Clinical practice guideline for screening and management of high blood pressure in children and adolescents. Pediatrics. 2017;140(3):e20171904.
- Chen X, Wang Y. Tracking of blood pressure from childhood to adulthood: A systematic review and meta–regression analysis. Circulation. 2008;117(25):3171–3180.
- Brook RD, et al. Particulate matter air pollution and cardiovascular disease. Circulation. 2010;121(21):2331–2378.
- Barker DJP. The developmental origins of adult disease. J Am Coll Nutr. 2004;23(6 Suppl):588S–595S.
- Thiering E, Heinrich J. Epidemiology of air pollution and diabetes. Trends Endocrinol Metab. 2015;26(7):384–394.
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