Reaching a better understanding of the modifiable factors associated with inflammatory and oxidative biomarkers in children would be relevant to the design of further investigation and prevention strategies. To determine the association of air pollution as well as dietary and physical activity habits with markers of inflammation, oxidative stress and insulin resistance for the first time in a population-based sample of children. We conducted a population-based study of 374 children, aged 10-18 years, and assessed the exposure of participants to air pollutants as well as their dietary and physical activity habits. In addition to anthropometric and blood pressure measurements, we determined the fasting serum levels of lipid profile, insulin and markers of inflammation and oxidation. We found independent associations between improper air quality and plasma markers of inflammation, oxidative stress and insulin resistance. The Pollutant Standard Index (PSI) and the level of fine particulate matter were significantly associated to all biomarkers studied. The associations between different markers of air pollutants and markers of inflammation, oxidative stress and insulin resistance remained significant after adjustment for age, gender, body mass index, waist circumference, healthy eating index and physical activity level. The association of healthy eating score with CRP and insulin resistance was mediated through anthropometric indices, and physical activity had independent association with insulin resistance. The independent influence of inflammatory/oxidative mechanisms of air pollution effects on surrogate markers of atherosclerosis from early life should be highlighted.