Socioeconomic Position and Mortality

To the Editor: The study by Dr Stringhini and colleagues¹ has again demonstrated a gradient in mortality, with lower socioeconomic position associated with higher mortality. Behaviors such as smoking, unhealthy diet, low levels of physical activity, and low alcohol consumption were strongly related to mortality. These behaviors were more prevalent among participants in the lower socioeconomic position.

Although these behaviors are important, environmental factors may also play an important role. Among these factors, air pollution with particulate matter (PM) classifications PM₁₀ and PM_2.5 (particles of ≤10 μm or ≤2.5 μm) has been associated with greater all-cause mortality.² Air pollution can be distributed differentially by socioeconomic position, so disadvantaged groups are more often exposed to air pollution.^3- 4 This differential exposure could have attenuated any improvements in health as a result of changes in healthy behaviors for people in lower socioeconomic positions and could explain the lack of effect on mortality by decreased smoking in the studied groups.