Elemental carbon exposure and lung function in school children from Mexico City.

Though exposure to air pollution has a detrimental effect on respiratory health, few studies have examined the association between elemental carbon exposure and lung function among schoolchildren. The aim of the present study was to present the association between short-term elemental carbon exposure and lung function in schoolchildren from Mexico City. 55 asthmatic and 40 non-asthmatic children were followed for an average of 22 weeks. A spirometry test was performed every 15 days during follow-up. Portable air samplers collected particulate matter onto Teflon filters. Gravimetric analysis was conducted and elemental carbon was quantified using transmission densitometry. The association between the main variables was analysed using linear mixed effects models. The mean ± sd of elemental carbon light absorption was 92.7 ± 54.7 Mm(-1). An increase of one interquartile range in the 24-h average of elemental carbon (100.93 Mm(-1)) was associated with a significant negative impact on forced expiratory volume in 1 s (FEV(1)) (-62.0 (95% CI -123.3- -1.2) mL) and forced expiratory flow at 25-75% of forced vital capacity (FVC) (FEF(25-75%)) (-111 (95% CI -228.3- -4.1) mL) among asthmatic children, equal to 3.3% and 5.5%, respectively; and on FEV(1) (-95.0 (95% CI -182.3- -8.5) mL) and FVC (-105.0 (95% CI -197.0- -13.7) mL) among non-asthmatic children. Exposure to elemental carbon resulted in an important negative effect on lung function in atopic schoolchildren, regardless of asthma status.