Exposure assessment for estimation of the global burden of disease attributable to outdoor air pollution

Abstract

Ambient air pollution is associated with numerous adverse health impacts. Previous assessments of global attributable disease burden have been limited to urban areas or by coarse spatial resolution of concentration estimates. Recent developments in remote sensing, global chemical-transport models, and improvements in coverage of surface measurements facilitate virtually complete spatially resolved global air pollutant concentration estimates. We combined these data to generate global estimates of long-term average ambient concentrations of fine particles (PM(2.5)) and ozone at 0.1° × 0.1° spatial resolution for 1990 and 2005. In 2005, 89% of the world's population lived in areas where the World Health Organization Air Quality Guideline of 10 μg/m(3) PM(2.5) (annual average) was exceeded. Globally, 32% of the population lived in areas exceeding the WHO Level 1 Interim Target of 35 μg/m(3), driven by high proportions in East (76%) and South (26%) Asia. The highest seasonal ozone levels were found in North and Latin America, Europe, South and East Asia, and parts of Africa. Between 1990 and 2005 a 6% increase in global population-weighted PM(2.5) and a 1% decrease in global population-weighted ozone concentrations was apparent, highlighted by increased concentrations in East, South, and Southeast Asia and decreases in North America and Europe. Combined with spatially resolved population distributions, these estimates expand the evaluation of the global health burden associated with outdoor air pollution.

Figure 1

Available measured (and estimated from PM₁₀ measurements) annual (2005) average PM_2.5 concentrations (μg/m³).

Figure 2

Estimated 2005 annual average PM_2.5 concentrations (μg/m³). The PM_2.5 estimates are generated from the grid cell average of SAT and TM5 and calibrated with prediction model incorporating surface measurements.

Figure 3

Histograms of selected regional (2005) annual average PM_2.5 concentrations for urban and rural grid cells. The regions are described in the Supporting Information and the urban and rural characterization based on the GPW3 population database (Supporting Information). Frequency denotes the number of grid cells with concentrations in a given range. Note difference in scales between regions.

Figure 4

Ratio of 2005:1990 annual average PM_2.5 concentrations. Concentrations are estimated to have increased in areas denoted by orange and red, while concentrations decreased in areas of yellow and green color.

Figure 5

Estimated (2005) seasonal (3-month) hourly maximum ozone concentrations (ppb).

Figure 6

Ratio of 2005:1990 seasonal (3-month) hourly maximum ozone concentrations. Concentrations are estimated to have increased in areas denoted by orange and red, while concentrations decreased in areas of yellow and green color.