Long-Term Exposure to Low-Level NO2 and Mortality among the Elderly Population in the Southeastern United States

Abstract

Background: Mounting evidence has shown that long-term exposure to fine particulate matter [PM in aerodynamic diameter ( )] and ozone ( ) can increase mortality. However, the health effects associated with long-term exposure to nitrogen dioxide ( ) are less clear, in particular the evidence is scarce for at low levels that are below the current international guidelines. Methods: We constructed a population-based full cohort comprising all Medicare beneficiaries (aged , ) in the southeastern United States from 2000 to 2016, and we then further defined the below-guideline cohort that included only those who were always exposed to low-level , that is, with annual means below the current World Health Organization guidelines (i.e., ). We applied previously estimated spatially and temporally resolved concentrations and assigned annual means to study participants based on their ZIP code of residence. Cox proportional hazards models were used to examine the association between long-term exposure to low-level and all-cause mortality, adjusting for potential confounders. Results: About 71.1% of the Medicare beneficiaries in the southeastern United States were always exposed to low-level over the study period. We observed an association between long-term exposure to low-level and all-cause mortality, with a 1.042 (95% CI: 1.040, 1.045) in single-pollutant models and a 1.047 (95% CI: 1.045, 1.049) in multipollutant models (adjusting for and ), per increase in annual concentrations. The penalized spline indicates a linear exposure–response relationship across the entire exposure range. Medicare enrollees who were White, female, and residing in urban areas were more vulnerable to long-term exposure. Conclusion: Using a large and representative cohort, we provide epidemiological evidence that long-term exposure to , even below the national and global ambient air quality guidelines, was approximately linearly associated with a higher risk of mortality among older adults, independent of and exposure. Improving air quality by reducing emissions, therefore, may yield significant health benefits. https://doi.org/10.1289/EHP9044

ZIP Code-Level Estimation of Air Quality and Health Risk Due to Particulate Matter Pollution in New York City

“…Specifically, future extensions of ZAPPA can add emerging knowledge on new adverse health impacts of exposure to PM 2.5 and incorporate treatment for additional pollutants, such as NO 2 from combustion sources, which are also known to cause adverse human health impacts. 67 …”

“…We anticipate that ZAPPA can be expanded to other cities in the U.S. and the world for assessing PM 2.5 -based health impacts, designing emissions reduction scenarios, and to further identify vulnerable populations with disproportionate exposures to air pollution sources. Specifically, future extensions of ZAPPA can add emerging knowledge on new adverse health impacts of exposure to PM 2.5 and incorporate treatment for additional pollutants, such as NO 2 from combustion sources, which are also known to cause adverse human health impacts …”

Invited Perspective: The NO2 and Mortality Dilemma Solved? Almost There!

“…In these investigations, a linear exposure–response was detected starting from a very low exposure level as in the Quin et al. ( 2021 ) study. It is important to note that all the studies together span at least three decades and took place in multiple cities and continents; consequently, combustion-related air pollution mixtures were quite different between study populations.…”

Comment on “Invited Perspective: The NO2 and Mortality Dilemma Solved? Almost There!”

“…The study by Qian et al. 2 that Forastiere and Peters examined appeared in the same issue of Environmental Health Perspectives as their perspective. As Forastiere and Peters noted, 1 this retrospective registry-based study in the southeastern United States showed a direct link between atmospheric nitrogen dioxide ( ) and mortality, and they noted also that had an independent effect after controlling for fine particulate matter (PM) and ozone.…”

“…Qian et al. 2 also compared results from studies conducted in different countries, all of which showed various adverse effects of . Forastiere and Peters argued that because “combustion-related air pollution mixtures were quite different between study populations … even if other important copollutants of were not assessed … it is unlikely that the observed associations of and mortality are solely attributable to one of those copollutants.” 1 The implication seems to be that acts by itself and is not a marker for a more complex exposure.…”