| Acute Respiratory Diseases and Carboxyhemoglobin Status in School Children of Quito, Ecuador Bertha Estrella,1,2 Ramiro Estrella,2,3 Jorge Oviedo,4 Ximena Narváez,3 María T. Reyes,3 Miguel Gutiérrez,3 and Elena N. Naumova5 1Corporación Ecuatoriana de Biotecnología, Quito, Ecuador; 2Universidad Central del Ecuador, Quito, Ecuador; 3Baca-Ortiz Children Hospital, Quito, Ecuador; 4Fundación Natura, Quito, Ecuador; 5Tufts University School of Medicine, Boston, Massachusetts, USA Abstract
Outdoor carbon monoxide comes mainly from vehicular emissions, and high concentrations occur in areas with heavy traffic congestion. CO binds to hemoglobin, forming carboxyhemoglobin (COHb) , and reduces oxygen delivery. We investigated the link between the adverse effects of CO on the respiratory system using COHb as a marker for chronic CO exposure. We examined the relationship between acute respiratory infections (ARIs) and COHb concentrations in school-age children living in urban and suburban areas of Quito, Ecuador. We selected three schools located in areas with different traffic intensities and enrolled 960 children. To adjust for potential confounders we conducted a detailed survey. In a random subsample of 295 children, we determined that average COHb concentrations were significantly higher in children attending schools in areas with high and moderate traffic, compared with the low-traffic area. The percentage of children with COHb concentrations above the safe level of 2.5% were 1, 43, and 92% in low-, moderate-, and high-traffic areas, respectively. Children with COHb above the safe level are 3.25 [95% confidence interval (CI) , 1.65-6.38] times more likely to have ARI than children with COHb < 2.5%. Furthermore, with each percent increase in COHb above the safety level, children are 1.15 (95% CI, 1.03-1.28) times more likely to have an additional case of ARI. Our findings provide strong evidence of the relation between CO exposure and susceptibility to respiratory infections. Key words: acute respiratory infections, carbon monoxide exposure, carboxyhemoglobin, children, Ecuador, traffic-related pollution. Environ Health Perspect 113:607-611 (2005) . doi:10.1289/ehp.7494 available via http://dx.doi.org/ [Online 14 January 2005]
Address correspondence to E. Naumova, Department of Public Health and Family Medicine, Tufts University School of Medicine, 136 Harrison Ave., Boston, MA 02111 USA. Telephone: (617) 636-2462. Fax: (617) 636-4017. E-mail: elena.naumova@tufts.edu We thank the directors of schools in Quito, Ecuador, for allowing access to the schools and to the children and their families for their willing participation in the study. Without the contribution of the Ellison Foundation and the Fundación Natura, this study would not have been possible. The authors declare they have no competing financial interests. Received 16 August 2004 ; accepted 13 January 2005.
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