Do fine particulate air pollution (PM2.5) exposure and its attributable premature mortality differ for immigrants compared to those born in the United States?

Abstract

In the United States (US), immigrants constitute a considerable and growing proportion of the general population. Compared to the US-born, immigrants have differential health risks, and it is unclear if environmental exposures contribute. In this work, we estimated disparities between immigrants and the US-born in fine particulate matter (PM_2.5) exposure and attributable premature mortality, including by region of origin and time since immigration. With PM_2.5 estimates from a validated model at ~1 km² spatial resolution and residential Census tract population data, we calculated the annual area-weighted average PM_2.5 exposure for immigrants overall, the US-born, and immigrants separately by geographic region of origin and time since immigration. We then calculated the premature mortality attributed to PM_2.5 for each population group, assessing disparities by immigrant status in PM_2.5 exposure and attributable premature mortality in the US as a whole and in each US county to evevaluate spatial heterogeneity. Overall, immigrants were exposed to slightly higher PM_2.5 (0.36 μg/m³, 3.8%) than the US-born. This exposure difference translates to 2.11 more premature deaths attributable to PM_2.5 per 100,000 in population for immigrants compared to the US-born in 2010. Immigrant - US-born disparities in PM_2.5 and attributable premature mortality were more severe among immigrants originating from Asia, Africa, and Latin America than those from Europe, Oceania, and North America. Disparities between immigrant groups by time since immigration were comparatively small. Sensitivity analyses using 2000 data and a non-linear set of PM_2.5 attributable mortality coefficients identified similar patterns. Our findings suggest that environmental exposure disparities, such as in PM_2.5, may contribute to immigrant health disparities in the US.

Keywords: Air pollution; Environmental justice; Health disparity; Immigrant health; PM2.5.

Figure 1:

County-Level Average Annual PM_2.5 and Population Immigrant Proportion (%) in United States Counties in 2010. Note: Immigrant proportion refers to the percentage of the population that was not born in the US. Counties. Census tracts with zero immigrants were shaded in white.

Figure 1:

County-Level Average Annual PM_2.5 and Population Immigrant Proportion (%) in United States Counties in 2010. Note: Immigrant proportion refers to the percentage of the population that was not born in the US. Counties. Census tracts with zero immigrants were shaded in white.

Figure 2:

Disparity between Immigrants and the US-Born in Premature Mortality Attributable to PM_2.5 Exposure in 2010. The coloring scheme indicates whether a county had higher or lower estimated premature deaths attributable to PM_2.5 in immigrants compared to the US-born (positive or negative premature mortality disparity) and whether the county was in the upper or lower half of county immigrant population proportions nationally. Counties with any Census tracts with zero immigrants were shaded in white. Density plots for each measure with its median value (dotted line) are also shown.

Figure 3:

Disparity between Immigrants and the US-Born in Premature Mortality Attributable to PM_2.5 Exposure by Immigrants’ Region of Origin in 2010. The coloring scheme indicates whether a county had higher or lower estimated premature deaths attributable to PM_2.5 in immigrants of the specified region of origin compared to the US-born and whether the county was above or below the national median for county immigrant population from the specified region of origin proportions.

Figure 4:

Disparity between Immigrants and the US-Born in Premature Mortality Attributable to PM_2.5 Exposure by Immigrants’ Time since Immigration in 2010. The coloring scheme indicates whether a county had higher or lower estimated premature deaths attributable to PM_2.5 in immigrants of certain time periods since immigration compared to the US-born and whether the county was above or below the national median for county immigrant population of a certain time since immigration proportions.