Effect of socioeconomic status on the association between air pollution and mortality in Bogota, Colombia

Air Pollution and Environmental Justice in Latin America: Where Are We and How Can We Move Forward?

PURPOSE OF REVIEW

Air pollution in Latin America is a major environmental threat, yet few studies have focused on aspects of environmental justice with regard to air pollution in the region. We examined the scientific literature and described whether and how this issue has been addressed, identify possible gaps in knowledge, and offer suggestions for future research to contribute to policies that seek greater equity concerning air pollution impacts in Latin America.

RECENT FINDINGS

There is a limited literature that has addressed issues of environmental justice or environmental health inequalities about air pollution in Latin America, with studies concentrated in Brazil, Mexico, and Chile. Studies that examined disparities in exposure to air pollution found a clear pattern of higher exposure in socially deprived areas. Studies that examined disparities in health impacts associated with air pollution have mixed results, but many found a clear modification of effect with those in the lower socioeconomic groups presenting greater effects. Despite Latin America's colonial and slavery history, no studies have considered ethnicity or minority populations. The literature shows that health risks (exposure and susceptibility) associated with air pollution are unevenly distributed among Latin American populations. Methodological approaches varied and can be improved in future studies, especially for exposure assessment to air pollution, as well as for assigning socioeconomic position to individuals. Using smaller geographic units and spatial regression techniques will allow a reduction in measurement error. Attempts should be made to include both individual and contextual socioeconomic indicators in the analysis. Better quality information will help understand these differential exposures and effects and provide inputs to policies to tackle these inequalities.

Individual and contextual socioeconomic status as effect modifier in the air pollution-birth outcome association

BACKGROUND

Several studies have examined whether air pollution is associated with adverse births outcomes, but it is not clear if socioeconomic status (SES) modifies this relationship.

OBJECTIVES

We investigated if maternal education and area-level socioeconomic status modified the relationship between ozone, nitrogen dioxide and particulate matter with aerodynamic diameter <10 μm (PM₁₀) on preterm births (PTB; gestational age <37 weeks) and term low birth weight (TLBW; weight < 2500 g on term deliveries).

METHODS

Analyses were based on almost 1 million singleton live births in São Paulo municipality between 2011 and 2016. The final sample included 979,306 births for PTB analysis and 888,133 for TLBW analysis. Exposure to PM₁₀, NO₂ and O₃ were based on date of birth and estimated for the entire gestation and for each trimester. Multilevel logistic regression models were conducted to examine the effect of air pollutants on both adverse birth outcomes and whether it was modified by individual and area-level SES.

RESULTS

In fully adjusted models, over the entire pregnancy, a 10 μg/m³ increase in O₃ and PM₁₀ was associated with increased chance of PTB (odds ratio; OR = 1.14 CI 1.13, 1.16 and 1.08 CI = 1.02, 1.15 respectively) and PM₁₀ with TLBW (OR = 1.08 CI 1.03, 1.14). Associations were modified by maternal educational and area-level SES for both outcomes. Mothers of lower education had an additional chance of PTB and TLBW due to PM₁₀ exposure (OR = 1.04 CI 1.04, 1.05 and 1.10 CI 1.08, 1.14 respectively), while mothers living in low SES areas have an additional chance for TLBW (OR = 1.05 CI 1.03, 1.06). Similar modification effects were found for O₃ exposure. Trimester specific associations were weaker but followed a similar pattern.

CONCLUSION

Socioeconomic status modifies the effect of air pollution on adverse birth outcomes. Results indicate that mothers with lower SES may be more susceptible to air pollution effects.

Development of a Health-Based Index to Identify the Association between Air Pollution and Health Effects in Mexico City

Health risks from air pollution continue to be a major concern for residents in Mexico City. These health burdens could be partially alleviated through individual avoidance behavior if accurate information regarding the daily health risks of multiple pollutants became available. A split sample approach was used in this study to create and validate a multi-pollutant, health-based air quality index. Poisson generalized linear models were used to assess the impacts of ambient air pollution (i.e., fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ground-level ozone (O3)) on a total of 610,982 daily emergency department (ED) visits for respiratory disease obtained from 40 facilities in the metropolitan area of Mexico City from 2010 to 2015. Increased risk of respiratory ED visits was observed for interquartile increases in the 4-day average concentrations of PM2.5 (Risk Ratio (RR) 1.03, 95% CI 1.01–1.04), O3 (RR 1.03, 95% CI 1.01–1.05), and to a lesser extent NO2 (RR 1.01, 95% CI 0.99–1.02). An additive, multi-pollutant index was created using coefficients for these three pollutants. Positive associations of index values with daily respiratory ED visits was observed among children (ages 2–17) and adults (ages 18+). The use of previously unavailable daily health records enabled an assessment of short-term ambient air pollution concentrations on respiratory morbidity in Mexico City and the creation of a health-based air quality index, which is now currently in use in Mexico City.

Análisis espacial de las concentraciones de PM2,5 en Bogotá según los valores de las guías de la calidad del aire de la Organización Mundial de la Salud para enfermedades cardiopulmonares, 2014-2015

Introducción.

La Organización Mundial de la Salud señala que tres millones de muertes al año por enfermedades cardiopulmonares están relacionadas con la exposición a la contaminación del aire.

Objetivo.

Estimar las superficies de concentración de partículas en suspensión de menos de 2,5 pm (Particulate Matter, PM₂₅) en Bogotá entre el 2014 y el 2015, clasificándolas según las guías de calidad del aire de la Organización Mundial de la Salud para enfermedades cardiopulmonares.

Materiales y métodos.

Se hizo un estudio ecológico mediante técnicas geoestadísticas. Se calcularon los promedios de PM₂₅ en lapsos de seis horas a lo largo del día en cuatro franjas horarias. Las concentraciones se clasificaron según los valores diarios y anuales de las guías de calidad del aire de la OMS.

Resultados.

La localidad de Kennedy presentó las mayores concentraciones de PM₂₅ en todas las franjas horarias. Los valores registrados en esta zona y clasificados según las guías diarias y anuales de calidad del aire, evidenciaron que la localidad presentaría un incremento de 1,2 % en la mortalidad cardiopulmonar en el corto plazo y de 9 % en el largo plazo.

Conclusión.

Las franjas horarias de las 0:00 a las 6:00 h y de las 12:00 a las 18:00 h, cumplieron con el valor anual de las guías de calidad del aire de 10 µg/m³ en una parte de la zona oriental de la ciudad. En el resto de la ciudad, en las franjas horarias de las 6:00 h a las 12:00 h y de las 18:00 h a las 24:00 h se registraron valores que cumplían los objetivos intermedios 2 y 3, lo que representa incrementos de 9 y 3 % en la mortalidad cardiopulmonar, respectivamente.

Short-Term Effects of Air Pollution on Respiratory and Circulatory Morbidity in Colombia 2011⁻2014: A Multi-City, Time-Series Analysis

Few studies have been conducted on the effect of air pollution on morbidity in Latin America. This study analyzed the effects of air pollution on respiratory and circulatory morbidity in four major cities in Colombia. An ecological time-series analysis was conducted with pollution data from air quality monitoring networks and information on emergency department visits between 2011 and 2014. Daily 24-h averages were calculated for NO₂, PM₁₀, PM_2.5, and SO₂ as well as 8-h averages for CO and O₃. Separate time-series were constructed by disease group and pollutant. Conditional negative binomial regression models were used with average population effects. Effects were calculated for the same day and were adjusted for weather conditions, age groups, and their interactions. The results showed that effects of some of the pollutants differed among the cities. For NO₂, PM₁₀, and PM_2.5, the multi-city models showed greater and statistically significant percentage increases in emergency department visits for respiratory diseases, particularly for the 5 to 9-year-old age group. These same pollutants also significantly affected the rate of emergency department visits for circulatory diseases, especially for the group of persons over 60 years of age.