Non-freeway NOx tracks children's BMI growth
In 4,550 Southern California children, non-freeway NOx associated with BMI at age 10 and 4-year growth; freeway NOx and near-road traffic density were weaker after confounding control.
Source
Traffic-related air pollution and obesity formation in children: a longitudinal, multilevel analysis
Study at a glance
- Design
- Cohort — Longitudinal multilevel BMI growth models vs traffic density and CALINE-like NOx
- N
- N=4550 · 4,550 children in 13 Southern California communities
- Population
- Schoolchildren in Southern California communities
- Outcome
- BMI level and 4-year growth related to non-freeway vs freeway NOx and near-road traffic
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Non-freeway NOx tracks children's BMI growth
These passages occur verbatim in the stored paper text. They support the points listed below; they do not verify every statement in the explanation.
BMI increased approximately 2.6 units by year 5, to 19.35.
By year 5 of the study BMI had increased approximately 2.6 units to 19.35 (SD 4.21) with boys showing a slightly greater increase.
Obesity rates were 15% for BMI at or above the CDC 95th percentile.
Obesity rates measured as BMI scores equal to or greater than the 95th percentile were 15%.
What they did
Multilevel growth models of measured BMI in a school cohort assigned baseline traffic density and CALINE-like freeway vs non-freeway NOx, adjusting for SES, smoking, greenness, fast food, and street connectivity.
What they found
Mean age 6.6 years; BMI rose ~2.6 units over 5 years. Traffic within 150 m was confounded (especially Spanish questionnaire). Non-freeway NOx stayed positively associated with BMI and slope; freeway NOx was not.
The limits
What it doesn't show
Observational BMI growth is not a randomized pollution trial; diet was not fully measured, and baseline-address exposure misses residential mobility.
Key terms
- Non-freeway NOx
- Modeled oxides of nitrogen from surface streets rather than freeways.
- BMI growth curve
- Intercept (level) and slope of body-mass index over childhood follow-up.
- Traffic density
- Vehicle activity within a 150 m home buffer.
- Gamma index
- Street-network connectivity affecting walking distances.
- NDVI greenness
- Vegetation around the home used as a neighborhood covariate.
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BMI growth associated with:
Common questions
Sample?
N = 4,550 children in 13 Southern California communities.
Which pollutant tracked BMI?
Non-freeway NOx, not freeway NOx.
Did 150 m traffic survive full adjustment?
Effect shrank >20% and lost borderline significance.
Entry age/BMI?
Mean 6.6 years; BMI 16.79.
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