Ambient fine particulate matter in Latin American cities: Levels, population exposure, and associated urban factors

Abstract

Background

Exposure to particulate matter (PM _2.5) is a major risk factor for morbidity and mortality. Yet few studies have examined patterns of population exposure and investigated the predictors of PM _2.5 across the rapidly growing cities in lower- and middle-income countries.

Objectives

Characterize PM _2.5 levels, describe patterns of population exposure, and investigate urban factors as predictors of PM _2.5 levels.

Methods

We used data from the Salud Urbana en America Latina/Urban Health in Latin America (SALURBAL) study, a multi-country assessment of the determinants of urban health in Latin America, to characterize PM _2.5 levels in 366 cities comprising over 100,000 residents using satellite-derived estimates. Factors related to urban form and transportation were explored.

Results

We found that about 172 million or 58% of the population studied lived in areas with air pollution levels above the defined WHO-AQG of 10 μg/m ³ annual average. We also found that larger cities, cities with higher GDP, higher motorization rate and higher congestion tended to have higher PM _2.5. In contrast cities with higher population density had lower levels of PM _2.5. In addition, at the sub-city level, higher intersection density was associated with higher PM _2.5 and more green space was associated with lower PM _2.5. When all exposures were examined adjusted for each other, higher city per capita GDP and higher sub-city intersection density remained associated with higher PM _2.5 levels, while higher city population density remained associated with lower levels. The presence of mass transit was also associated with lower PM _2.5 after adjustment. The motorization rate also remained associated with PM _2.5 and its inclusion attenuated the effect of population density.

Discussion

These results show that PM _2.5 exposures remain a major health risk in Latin American cities and suggest that urban planning and transportation policies could have a major impact on ambient levels.

Graphical abstract

Highlights

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  Cities in Latin America with higher GDP, motorization rate, and congestion have higher PM _2.5.

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  Cities in Latin America with higher population density and green space have lower levels of PM _2.5.

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  Intersection density and mass transit infrastructure also impact pollution levels.

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  Urban planning and transportation policies may have a major impact on air pollution.