Anemia prevalence and hemoglobin levels are associated with long-term exposure to air pollution in an older population

Abstract

BACKGROUND Anemia, a highly prevalent disorder in elderly populations, is associated with numerous adverse health outcomes, including increased mortality, impaired functional status and cognitive disorders. Approximately two-thirds of anemia in American elderly is caused by chronic inflammation or is unexplained. A potential contributing factor may include air pollution exposures, which have been shown to increase systemic inflammation and affect erythropoiesis. Few studies, however, have investigated the associations of air pollution on hemoglobin levels and anemia. METHODS We used linear regression models and modified Poisson regression with robust error variance to examine the associations of particulate matter (PM2.5) and nitrogen dioxide (NO2) on hemoglobin concentrations and prevalence of anemia, respectively, among 4,121 older Americans enrolled in the National Social Life, Health, and Aging Project. We estimated participant-specific exposures to PM2.5 using spatio-temporal models, and to NO2 using nearest measurements from Environmental Protection Agency’s Air Quality System. Hemoglobin levels were measured for participants in each of two data collection waves from dried blood spots. Anemia was defined using World Health Organization hemoglobin-based criteria of <13 and <12 g/dL for men and women, respectively. Models were adjusted for age, sex, smoking status, race, income, education, neighborhood socioeconomic status, region, urbanicity and medication use. Mediation by C-reactive protein (CRP), a marker of systemic inflammation, was also investigated. RESULTS An inter-quartile range (IQR, 3.9 μg/m3) increase in the one-year moving average PM2.5 was positively associated with anemia prevalence (prevalence ratio, or PR 1.33, 95% CI: 1.23, 1.45) and decreases in average hemoglobin of 0.81 g/dL (p<0.001). Similarly, an IQR (9.6 ppb) increase in NO2 was associated with anemia prevalence (PR 1.43, 95% CI: 1.25, 1.63) and a decrease in average hemoglobin of 0.81 g/dL (p<0.001). Strong dose-response relationships were identified for both pollutants. Mediation of the effect of PM2.5 by CRP was also identified (P=0.007). CONCLUSIONS/INTERPRETATIONS Air pollution exposures were significantly associated with increased prevalence of anemia and decreased hemoglobin levels in a cohort of older Americans. If causal, these associations could indicate that chronic air pollution exposure is an important risk factor for anemia in older adults.

Air pollution impairs recovery and tissue remodeling in a murine model of acute lung injury

“…Some of the effects observed could be related to the air pollution itself, without the LPS interference, such as the anemia and elastosis displayed by the PM and LPS + PM groups. Previous studies have observed higher prevalence of anemia, lower hemoglobin levels and decreased red cell count associated to exposure to higher PM 2.5 levels in an older population 19 and in children 20 . Regarding the elastosis, another study from our group showed that the exposure to the São Paulo City air pollution promoted elastic fibers’ deposition in almost all sized arterioles from both ventricles 21 ; however, the mechanism by which the particulate matter could promote elastosis remains to be elucidated.…”

Fatigability as a Predictor of Subclinical and Clinical Anemia in Well‐Functioning Older Adults

“…27,28 We have no definitive explanation for the markedly lower anemia prevalence in black men except that, similar to the other participants in BLSA, black participants had much higher educational attainment and income than individuals with the same characteristics in the general population, both of which were associated with lower anemia rates. 29 The 30% overall prevalence of subclinical anemia, especially in a cohort of well-functioning older adults, warrants some discussion. As noted in the introduction, sexspecific hemoglobin values up to 1 g/dL above the WHO anemia cutpoint threshold were associated with elevated rates of mortality.…”

Air Pollution and Noncommunicable Diseases

“…73 Indoor air pollution has been shown to be a risk factor for anemia in young children 74 as well as the elderly. 75 Air pollution may increase hemoglobin distortion in sickle cell disease. The resulting microvascular obstruction leads to lack of oxygen and severe pain.…”