Written by Chrystal Moulton, Staff Writer. Pollution in major urban regions of Latin America was associated with increases in daily mortality from all natural causes.
The purpose of this study was to investigate the effects of air pollution on mortality in different age groups.
This study was conducted in Latin America, which is known to be densely populated in the urban regions. In fact, in four of the major cities in this part of the world (Rio de Janeiro, Santiago, Mexico City, and Sao Paulo) the number of people who live in these cities combined is around 34 million. Rapid urbanization has led to issues with air pollution in such cities in Latin America. Therefore, researchers from three countries headed by the Health Effects Institute set out to see if exposure to particle matter and ozone has any effect on mortality rates for all causes in each of the three countries where they reside: Mexico, Chile, and Brazil. This research focused on nine cities: Sao Paulo, Rio de Janeiro, and Porto Alegre in Brazil, Santiago, Temuco, and Concepcion in Chile, Mexico City, Monterrey, and Toluca in Mexico.
From 1997-2005, air pollution and mortality data was collected in all nine cities. Data was extensively reviewed, assembled and stored in a database for analysis available to the researchers. Mortality was categorized by a range of cause-of-death categories in order to account for underlying cause of death. Categorization was also done by age groups starting from infants to 65 years and older. Results were calculated by risk percent changes (RPCs). In this study, the risk percent change is the increase in the risk of death due to an increase of 10mcg/m3 of particle matter concentration or a 10mcg/m3 increase in the daily maximum average concentration of ozone.
Researchers found that particle matter was associated with a small percentage increase in daily mortality from all natural causes in all age groups for 7 out of the 10 cities studied (except Concepcion, Temuco, and Toluca) (p<0.05). Increase in ozone concentration was associated with an increased risk of all-natural cause, all-age mortality in Mexico City (0.22%), Monterrey (0.73%), and Rio de Janeiro (0.13%) (p<0.05). When examined over seasonal changes in temperature, association of ozone and risk percent changes in daily morality during the warm season were significant for Monterrey (0.94%), Sao Paulo (0.64%), and Rio de Janeiro (0.31%). Similarly, during the cold season, percent changes in mortality were significantly high in all the cities of Mexico. Risk percent changes in cardiopulmonary mortality and a 10mcg/m3 increase in particle matter was significant in all cities and all age groups except Concepcion. In all cities except Toluca, percent change in daily mortality related to COPD or other respiratory diseases increased significantly with a 10mcg/ m3 increase in particle matter in all age groups.
Researchers also investigated the effect of particle matter and ozone on respiratory deaths in children in the three largest cities: Santiago, Sao Paulo, and Mexico City. They found that an increase in particle matter was associated with a small but significant increase in risk percent changes in infants (0.64%) and children aged 1-4 years old (0.61%) living in Santiago and a significant decrease in infants living in Sao Paulo (-3.96%) (p<0.05). Significant increases in lower respiratory tract infection was observed in infants in Mexico City (1.38%) and for children 1-14 years old in Santiago (1.28%) (p<0.05). Increases in ozone were associated with an increase in risk of respiratory death in children 1-4 years old (1.49%) and death from lower respiratory infection in infants and children 1-14 years old in Mexico City (0.85% and 1.76%, respectively) (p<0.05).
Changes in ozone viewed by seasons showed significant increase in RPCs associated with respiratory death in children 1-4 years old (2.02%) and lower respiratory infection in infants (0.78%) and children aged 1-14 years (2.53%) in Mexico City (p<0.05) in the cold season. RPCs related to respiratory death in Santiago significantly decreased in infants during the cold season (-1.11%, p<0.05) and in Sao Paulo percent changes in risk of mortality by lower respiratory infection were significantly lower in infants (-6.93%) and high in children age 1-14 years old (4.73%) (p<0.05%). During the warm season, increase in ozone was associated with a 4.32% increase RPC for respiratory death in infants living in Sao Paulo and a 3.31% increase in children 1-4 years old in Mexico City. In Santiago, however, significant decrease in respiratory death in children aged 1-4 years old and lower respiratory infection death in children aged 1-14 years old (-5.42% and -3.11%, p<0.05, respectively).
Overall, researchers concluded that the effect of particle matter on all natural- cause mortality in all age groups (0.61%) was similar to a meta-analysis of 17 separate studies of Latin American cities conducted in 2005 by the Pan American Health Organization.
Source: Romieu, Isabelle, N. Gouveia, Luis A. Cifuentes, A. Ponce de Leon, W. Junger, J. Vera, V. Strappa et al. “Multicity study of air pollution and mortality in Latin America (the ESCALA study).” Research report (Health Effects Institute) 171 (2012): 5-86.
© 2012 Health Effects Institute, Boston, Mass., U.S.A. Romieu et al 2012
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Posted September 16, 2013.
Chrystal Moulton BA, PMP, is a 2008 graduate of the University of Illinois at Chicago. She graduated with a bachelor’s in psychology with a focus on premedical studies and is a licensed project manager. She currently resides in Indianapolis, IN.
Reference:
- Multicity study of air pollution and mortality in Latin America (the ESCALA study). Romieu I, Gouveia N, Cifuentes LA, et al. Res Rep Health Eff Inst. 2012 Oct;(171):5-86.
