Researchers at Virginia Commonwealth University Medical Campus say air pollution does more than cause asthma; it damages the brain.
"While it is well known that air pollution affects human health through cardiovascular and respiratory morbidity and mortality, it has only recently been shown that these deleterious effects extend to the brain," says researcher Michelle Block, "Air pollution has been implicated as a chronic source of neuroinflammation and reactive oxygen species that produce neuropathology and central nervous system disease."
Stroke, Alzheimer´s, and Parkinson´s disease have all been linked to air pollution.
Changes in the blood-brain barrier are a key component in the way air pollution affects the brain and central nervous system. When the blood-brain barrier becomes more permeable, pollution has greater access to the brain.
When air pollution reaches the brain and activates the resident innate immune response, it becomes a chronic source of pro-inflammatory factors and reactive oxygen species that leads to neurodegenerative disease and diseases of the central nervous system. Particulate matter is the primary culprit. The World Trade Center terrorist attacks are a perfect example of particulate matter pollution that led to the these types of diseases in rescue workers.
Block says that the "impact of air pollution upon the brain was first noted as an increase in ischemic stroke frequency found in individuals exposed to indoor coal fumes." Stroke is the number one cause of disability in the United States and is the third leading cause of death.
Air pollution is believed to lead to cerebral vascular damage, neuroinflammation, and neurodegeneration through four routes.
First, air pollution leads to systemic inflammation that is implicated in stroke and neurodegenerative diseases by causing a disruption of cytokines.
Second, ultrafine particles have easier access to systemic circulation and, thus, the brain.
Third, nanoparticles provide toxicants an ideal entry to the brain. Nanoparticles are currently being evaluated as a better way to deliver medications to the central nervous system. As such, nanoparticles also provide effective delivery of toxicants to the central nervous system and brain.
Finally, ozone is a reactive oxygen species and powerful inhaled oxidizing agent according to Block. When inhaled, ozone reacts with proteins and lipids to generate modifications, free radicals, and toxic compounds.
Air pollution contains both particulate matter and gasses is not limited to industrial emissions. Indoor air is often more contaminated than outdoor air. Pesticides, air "fresheners", cleaning products, plastics, and formaldehyde from furniture and clothing are common indoor air pollutants.
Indoor air pollution is exacerbated by tightly sealed, energy efficient buildings which don´t allow for open windows and continuous ventilation. As such, contaminants easily accumulate to toxic levels.
Block ML, Calderón-Garcidueñas L. Air pollution: mechanisms of neuroinflammation and CNS disease. Trends Neurosci. 2009 Sep;32(9):506-16. Epub 2009 Aug 26.
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