Introduction
Dust particles can cause serious health issues due to harmful and toxic substances present in the air. These particulate matters are often linked with various respiratory and cardiovascular diseases. However, its association with neurological conditions has also been recognized in multiple studies, which show the effect these pollutants have on brain development and other related conditions.
How Does Air Pollution Affect the Brain?
Air pollution contains contaminants like toxic gasses, heavy metals, and particulate matter (PM10 and PM2.5), which cause brain-related disorders affecting the brain's functioning, development, and quality of life. Exposure to pollutants in the air causes inflammation in the brain as a defensive mechanism to fight these toxic substances, but chronic inflammation can be fatal to the brain.
One study investigates the impact of various air conditions, focusing on the effects of traffic-related particulate matter with an aerodynamic diameter of less than 1 micrometer (PM1), high-efficiency particulate air (HEPA)-filtered air, and clean air on the brain structure. The effects of air on the brain include a range of factors, such as possible correlations between cognitive performance and air quality, the onset or aggravation of neurological conditions, and the general state of neural structures.
What Are the Brain-Related Diseases Caused by Air Pollution?
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Dementia and Cognitive Function - Various studies show that metabolic and oxidative deformity or irregularity in the brain is associated with air pollution, leading to a defective insulin signaling process, causing a high risk of dementia and low cognitive function. It has also been found that resistance to glucose can cause memory loss, and the inability to absorb glucose due to insulin resistance in the cerebrum can develop the risk of dementia. Also, exposure to PM2.5 dust can affect clean air in the brain. It produces changes in the structure and functioning of mitochondria and causes cognitive and neurological impairments.
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Stroke - Various stroke incidences show an association of increased risk of stroke due to particulate matter in the air, causing thrombosis in blood vessels. These dust particles in air pollution can cause acute coronary syndromes, thrombosis, atherosclerosis, arrhythmia, and inflammation as an underlying cause of stroke. In addition, some toxins in the air, such as NO2 and PM10, can cause ischemic stroke.
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Depression - Studies show that air pollution affects cortisol levels in the brain, and glucocorticoid sensitivity to the brain can cause depression in people because cortisol is a stress hormone and can lead to depression and cognition in people. The central nervous system (CNS) reacts to stress through the pituitary gland and hypothalamus, which help secrete high cortisol levels in the brain. Thus, air pollution activates glucocorticoid receptors, related neurotrophic factors, and other inflammatory reactions, which cause neurotoxicity and neurogenesis, leading to depression and impaired neurological conditions.
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ADHD (Attention Deficit Hyperactivity Disorder) - Various studies show air pollution and its association with child brain development. PM2.5 and NO2 concentrations in the air in residential areas have significantly increased ADHD risks in children. In addition, some studies suggest that late pregnancy exposure to particulate matter in air pollution can also reduce the corpus callosum region of the brain.
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Neurodevelopment - Brain development can be significantly affected by the particulate matter in air pollution, which contains harmful elements such as arsenic, lead, methylmercury, and others, which have a neurotoxic effect. It has also been found that these pollutants in the air can affect brain development more in fetal life than in childhood because the maximum structure of the brain develops during infancy and causes brain damage and neuro impairment in later life.
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Schizophrenia - This is a chronic mental disorder affecting millions of people around the world and has more prevalence in urban areas. An association of particulate matter, NO2, and SO2 with an increased risk of schizophrenia is discussed in various studies. Moreover, the worsening symptoms of schizophrenia were found to be associated with high levels of PM2.5, especially in patients above 65 years old.
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Multiple Sclerosis - It is a neurodegenerative and inflammatory disease of the central nervous system. Studies have shown the association between particulate matter and multiple sclerosis through various hypotheses. For example,
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The lungs absorb particulate matter through the respiratory tract, causing activation of T-cells by pulmonary inflammation and causing the brain to secrete cytokinin.
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The Olfactory bulb absorbs particulate matter directly and causes inflammation in the brain. This leads to a condition called multiple sclerosis. Also, environmental pollution, dust particles, and smoke can cause DNA modification and lead to multiple sclerosis.
How Does Air Pollution Affect the Central Nervous System?
The toxic particles in the environment travel through the olfactory nerve into the brain, blood-brain barrier, vagus nerve, or via the olfactory bulb as a direct route for absorption into the nervous system. Air pollution affects the brain through two processes: oxidative stress and inflammation reactions. Oxidative stress was related to the toxins released by diesel vehicles, which can affect the neurons and microglial cells and lead to neurodegenerative conditions. It has also been associated with Alzheimer’s and Parkinson's disease in some studies showing an increase in frontal, temporal, and midbrain exposure to air pollutants.
How to Cope With Pollution-Related Brain Diseases?
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Exposure to air contaminants must be reduced to fight neurological diseases through pollution.
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Antioxidant supplements such as vitamins C and E can fight against oxidative stress caused by particulate matter in the brain.
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Cardiovascular exposure to toxic contaminants in the air can be mitigated by the help of unsaturated fatty acids (olive oil and fish oil).
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Dietary vitamin B can be used to reduce the gene methylation in mitochondria caused by PM2.5.
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Apart from this, using gasoline vehicles in place of diesel motors can reduce pollution and its impact on health.
What Actions Can Be Done to Alleviate Problems Associated With Air Pollution?
While dealing with air pollution is a global challenge, there are encouraging global examples of how to do so. Here are some practical steps:
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London, UK: To improve air quality, London is expanding its Ultra Low Emission Zone (ULEZ) across all boroughs from August 2023. This means that highly polluting vehicles will need to pay a daily charge to drive in these areas.
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Edinburgh, UK: The city has transformed its center by creating car-free streets and enhancing public transport, making it more pedestrian-friendly.
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Barcelona, Spain: Car-free streets called 'superblocks' have helped reduce air pollution in Barcelona. The city also plans to increase green spaces, which can positively impact residents' mental health.
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Paris, France: This place is working on its Paris Climate Action Plan, involving over 500 actions to become carbon-neutral and use 100 percent renewable energy. They are also aiming to ban diesel vehicles and achieve 100 percent 'clean vehicle' use by 2030.
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Netherlands: The country is implementing low-emission zones for high-polluting vehicles, ensuring all new buses are zero-emission by 2025 and reducing parking fees for less-polluting vehicles.
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Milan, Italy: Milan plans to convert its entire public transport network to electric by 2030, contributing to cleaner air in the city.
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Bogota, Colombia: Bogota is addressing pollution by improving its cycle network. They also encourage the adoption of green roofs and vertical gardens in public spaces and private buildings.
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Beijing, China: The introduction of the 'Green Traveler Platform' in Beijing tracks users' environmentally friendly behaviors through smart devices. Users are rewarded with credits, redeemable for cash, for reducing their impact on the environment.
Conclusion
Air pollution causes serious health risks and is found to be a harmful environmental factor causing millions of deaths every year worldwide. The particulate matter in the air, consisting of toxic gasses, organic and inorganic compounds, heavy metals, and toxins released from vehicle pollution, deteriorates a person's health. It causes various skin, cardiovascular, respiratory, and neurological diseases. In addition, studies show how neurotoxicants present in the air damage the brain and cause multiple psychiatric disorders. However, researchers are still finding better intervention methods to treat mental health caused by pollution and ways to minimize them. An environment with reduced levels of pollutants may help create a more favorable atmosphere for brain health by maintaining clean air on the brain structure.