Age-adjusted estimated mean levels (95%CI) of coronary risk factors in 60 year old men in manual and non-manual groups and their changes between 1978–80 and 1998–2000.

<p>Analyses for each risk factor are restricted to subjects with risk factor information at both time points.</p><p>*p for interaction  =  social class*time interaction.</p

Current smoking in manual compared with non-manual groups in 1978–80 and 1998–2000.

<p>*p for interaction  =  social class*time interaction.</p

Published studies reporting the effect of NO₂ on absolute differences in FEV₁ in children.

<p>Results expressed for a 10 μg/m³ increase in the levels of NO₂.</p

Median weekday physical activity levels (CPM) from 7 am to midnight by mode of travel to school.

<p>Median weekday physical activity levels (CPM) from 7 am to midnight by mode of travel to school.</p

PRISMA Flow-Diagram of the systematic review.

<p>PRISMA Flow-Diagram of the systematic review.</p

Summary statistics by gender in CHASE study.

<p>Values are numbers (percentages) of participants unless stated otherwise.</p

Distribution summary of pollutants at the home address of participants and metrics of traffic proximity in CHASE study.

<p>IQR: inter quartile range</p><p>Results based on data averaged over 2005 and 2006.</p

Mean weekend levels of physical activity by mode of transport to school.

<p>Mean differences compare level of physical activity in children who travel by public transport or car, to those who walk or cycle to and from school.</p><p>Analyses are adjusted for gender, age quartiles, day order, day of week (i.e., Saturday or Sunday), month, ethnicity and random effects for child and school.</p

Published studies on the effect of NO₂ on percent reduction in lung function in children.

<p>Results expressed for a 10 μg/m3 increase in the levels of NO₂.</p

Random effects meta-analysis of the association between concentration of NO₂ and FEV₁.

<p>Linear models. Results expressed as absolute differences in FEV₁ for a 10 μg/m³ increase in the levels of NO₂.</p