Effect of PM10and 03on infant mortality among residents in the Mexico City Metropolitan Area: a case-crossover analysis, 1997—2005

• Published in: Journal of epidemiology and community health (1979) 2011-08, Vol.65 (8), p.715-721
• Main Authors: Carbajal-Arroyo, L, Miranda-Soberanis, V, Medina-Ramón, M, Rojas-Bracho, L, Tzintzun, G, Solís-Gutiérrez, P, Méndez-Ramírez, I, Hurtado-Díaz, M, Schwartz, J, Romieu, I
• Format: Article
• Language: English
• Subjects: Air pollution; Causes of death; Community health; Death; High socioeconomic status; Infant mortality; Life tables; Mortality; Particulate matter; Research report; Socioeconomic status
• ISSN: 0143-005X; 1470-2738

Introduction: Consistent evidence has shown a positive association between air pollution and daily mortality among adults. Less is known about its effect on infant mortality and the modification of this association by socioeconomic status (SES). Objective: To assess the association of particulate matter with an aerodynamic diameter of ≤10 μm (PM 10 ) and ozone (O 3 ) on infant mortality and its modification by SES. Methods: We evaluated the relationship of 24 h mean PM 10 and 1 h daily maximum O 3 levels with 12 079 all-cause deaths (3903 respiratory deaths) among 1- to 11-month-old infants residing in the Mexico City Metropolitan Area between January 1997 and December 2005 using a case-crossover approach. The data were analysed using conditional logistic regression models, controlling for weather conditions and day of the week. Results: Single-effect models showed, for all-cause mortality, increases of 5.5% (95% CI 1% to 10%) at lag1 and 6.6% (2% to 11.4%) at lag2; cumulative exposure models (0—2 days) showed an increase of 6.3% (0.01% to 32.7%). Respiratory mortality increased marginally at 5.3% (-0.02% to 13.2%) with a 1-day lag and 10% (2.1% to 18%) with a 2-day lag per increase of 38.7 μg/m 3 (IQR) in PM 10 levels. When data were stratified by SES (low, medium, and high), only infants with low and medium SES presented a significant increase in risk of all-cause mortality and respiratory mortality in relation to PM 10 . O 3 was only significantly related to respiratory mortality in low SES. Conclusion: Our results suggest that in the Mexico City Metropolitan Area, infants with lower SES (low to medium) are at higher risk of mortality when exposed to ambient PM 10 and O 3 .