Particulate Air Pollution and Risk of Neuropsychiatric Outcomes. What We Breathe, Swallow, and Put on Our Skin Matters

Abstract

We appraise newly accumulated evidence of the impact of particle pollution on the brain, the portals of entry, the neural damage mechanisms, and ultimately the neurological and psychiatric outcomes statistically associated with exposures. PM pollution comes from natural and anthropogenic sources such as fossil fuel combustion, engineered nanoparticles (NP ≤ 100 nm), wildfires, and wood burning. We are all constantly exposed during normal daily activities to some level of particle pollution of various sizes—PM2.5 (≤2.5 µm), ultrafine PM (UFP ≤ 100 nm), or NPs. Inhalation, ingestion, and dermal absorption are key portals of entry. Selected literature provides context for the US Environmental Protection Agency (US EPA) ambient air quality standards, the conclusions of an Independent Particulate Matter Review Panel, the importance of internal combustion emissions, and evidence suggesting UFPs/NPs cross biological barriers and reach the brain. NPs produce oxidative stress and neuroinflammation, neurovascular unit, mitochondrial, endoplasmic reticulum and DNA damage, protein aggregation and misfolding, and other effects. Exposure to ambient PM2.5 concentrations at or below current US standards can increase the risk for TIAs, ischemic and hemorrhagic stroke, cognitive deficits, dementia, and Alzheimer’s and Parkinson’s diseases. Residing in a highly polluted megacity is associated with Alzheimer neuropathology hallmarks in 99.5% of residents between 11 months and ≤40 y. PD risk and aggravation are linked to air pollution and exposure to diesel exhaust increases ALS risk. Overall, the literature supports that particle pollution contributes to targeted neurological and psychiatric outcomes and highlights the complexity of the pathophysiologic mechanisms and the marked differences in pollution profiles inducing neural damage. Factors such as emission source intensity, genetics, nutrition, comorbidities, and others also play a role. PM2.5 is a threat for neurological and psychiatric diseases. Thus, future research should address specifically the potential role of UFPs/NPs in inducing neural damage.

Differences in the characteristics and pulmonary toxicity of nano- and micron-sized respirable coal dust

“…The entry of dust particles into cells can cause mitochondrial damage [ 35 , 36 ]. Changes in the number, size and structure of mitochondria often occur when cells are damaged by toxicants.…”

Air Pollution, Ultrafine Particles, and Your Brain: Are Combustion Nanoparticle Emissions and Engineered Nanoparticles Causing Preventable Fatal Neurodegenerative Diseases and Common Neuropsychiatric Outcomes?

“…Nontailpipe vehicular emissions from brake and tire wear, catalyst metal degradation and resuspended road dust in the quasi-ultrafine size range (PM 0.2 ) are increasingly important sources of PM and metals in Southern California . Accordingly, evaluation of potential health effects, including neuropsychiatric outcomes, ought to consider emissions sources within cities, across cities, and countries …”

“…It is extremely worrisome to see abnormal proteins, distinctive of fatal neurodegenerative diseases already in the brains of babies and teens and to document in the very same populations significant cognitive deficits and brain structural changes. The public needs greater awareness that where you live, what you are breathing and swallowing, how you travel, and your occupational life-long history are indeed very important determinants of health . In fact, clinical histories should include such information.…”

Environmental Nanoparticles Reach Human Fetal Brains

“…Millions of people are exposed to environments with concentrations of fine particulate matter (PM 2.5 ) above current USEPA standards, a well-known global risk factor of cardiovascular, respiratory, neurological and psychiatric morbidity and mortality [ 1 , 2 , 3 , 4 ]. Combustion, natural (soil, volcanic) ultrafine particulate matter (UFPM), and engineered nanoparticles (NPs) are key components of PM 2.5 air pollution [ 5 , 6 , 7 , 8 ].…”