Long-term PM2.5 Exposure and Neurological Hospital Admissions in the Northeastern United States

by Thy Annie Nguyen

Many prior studies have suggested that particulate matter (PM) exposure may induce an inflammatory response that leads to neurodegenerative diseases and cognitive decline. PM has been known to carry heavy metals, induce free radicals, and contain carcinogens. Especially with PM2.5 (particulate matter ≤ 2.5 μm) being small enough to potentially cross the blood brain barrier, it is worth studying how these aerial pollutants may affect neurological health. In a study from 1999 to 2010 in the northeastern United States, Kioumourtzoglou et al. (2016) found a correlation between long-term exposure in dense, urban cities that produced large quantities of PM2.5 and accelerated disease progression in Alzheimer’s Disease (AD), Parkinson’s Disease (PD), and dementia. Approximately 9.8 million residents in 50 cities were surveyed while air pollution data was collected from the EPA’s Air Quality System Database. Although the design of the study prohibited an analysis of the role of PM2.5 in disease onset, researchers were able to measure the effects PM2.5 concentrations had on the current population of neurological patients who had already exhibited the onset of disease. Results from the long-term survey found that higher concentrations of PM2.5 contributed to a significant severity in neurodegeneration in existing AD, PD, and dementia patients. Hazard risk (HR) increased for all three groups with PD admissions HR = 1.08, AD HR = 1.15, and dementia HR = 1.08. In addition, these incidences of disease are more likely to affect an aging population, which tends to be susceptible to environmental insults and is the group most likely to see the onset of neurological disease. PM2.5 and other airborne pollutants lead to oxidative stress and inflammation that resulted in aggravated neurodegeneration. With aberrant neuronal death, the onset of diseases such as AD and PD may be more likely and existing symptoms more severe. Kioumourtzoglou et al. contributes to the current discussion of environmental toxicology with their study assessing how long-term exposure to PM2.5 may affect human health and the progression of common neurological diseases. Looking at current populations of humans in relevant conditions, fluctuations of PM2.5 were shown to significantly impact mortality and severity of disease.


Kioumourtzoglou, Marianthi-Anna, et al. “Long-term PM2. 5 exposure and neurological hospital admissions in the northeastern United States.” Environmental health perspectives 124.1 (2016): 23.




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