Cognitive Climate: Air Pollutants and Brain Health; By Aubree Kozie and David Omkar Webster

Smokestacks, chemtrails, and exhaust pipes are typically recognized as necessary side-effects to modern human life, the “cost of doing business” if you will. News and media programming, legislature, and large corporations all normalize and tout these things as benign elements of progress, plenty, and prosperity.


It was not long ago that cigarettes were sold to the American people under the same false bill of goods, as glamorous, progressive and safe. But research increasingly indicates that these smoke-spilling technologies have a lot more in common with cigarettes than just their advertising campaigns — they both degrade health and wellbeing gradually by way of the respiratory system. Increasingly research indicates that exposure to atmospheric toxins in the air are taking their toll on human cognitive health, and suggesting that brain fog may be partially accounted for by environmental smog.


Atmospheric Experimentation 


This line of inquiry began when environmental researchers began to observe increasing levels of air pollution, particularly in urban areas. These issues are ones you are likely to have heard of and may have even seen grace the pages of your newspaper in articles concerning global warming and the climate crisis. The severity of the problem was demonstrated recently when the lockdown of Wuhan, China caused emissions to plummet to some of the lowest in years and revealed whole mountain ranges previously shrouded in smog. 


But further experimentation has revealed that the climate crisis is having a much broader effect than just upon nature itself, and that toxicity in our air has become so severe that it is contributing to disease. 


Across the globe from China, in Mexico City, which has an extreme and notorious air pollution problem and was voted the most polluted megacity on the planet in 1992, decades of research has revealed that 203 autopsies of cases of sudden death showed brain tissue with proteins amyloid-ß and hyperphosphorylated tau. Both proteins are biomarkers of Alzheimer’s disease (AD) and other neurodegenerative conditions. 


But this was not the most striking finding of this post-mortem research. Researchers found these AD-associated proteins in the brains of those as young as 11 months old. Brain changes of this kind are nearly unheard of in people that young. The investigators believe air pollution is likely the cause of the development of the cognitive abnormalities observed in the population, as well as many other detrimental changes to the brains of Mexico City’s residents documented over the last three decades (Offord, 2019). 


Global Repercussions


Mexico City and Wuhan are not outliers when it comes to levels of air pollutants. Globally, nearly all urban areas are seeing increases in CO2 emissions and other toxic particles. Increasing incidences of respiratory and cardiovascular problems seem to confirm patterns of the degenerative effects of air pollution on human health. A report as recently as 2018 by the Health Effects Institute found up to 95 percent of earth’s inhabitants were breathing unsafe air. At the World Health Organization’s 2019 fall conference on air pollution, dirty air was implicated in more than 7 million deaths per year (Offord, 2019). 


The idea that the environment plays a role in chronic and autoimmune conditions is nothing new, however specific links between air toxicity and cognitive impairment are more recent. 

While CO2 emissions are a significant element of air pollution, there are a number of other toxins which contribute to poor air quality and the health repercussions which follow. 


Other airborne contaminants besides carbon emissions include noxious gases such as nitrogen oxides, sulfur dioxide, and ozone, fine particulate matter such as dust, soot, mold, virus and bacteria, and nanospheres of metals that penetrate deep into the human body. Additionally, many building materials include chemicals which are emitted while in use or even after via the process of off gassing from products such as stains, paints, carpets, chemicals from cleaning products and anything with fire-retardant spray (which is legally required on many products). Data indicates that often indoor air is even worse, up to 2-5 times more toxic than outdoor air, which is significant given the US population spends 90% of its time indoors. 


Research shows that fine particle pollutants as small as 1/30th the width of a human hair enter the air from various pollutants listed above and can remain airborne and inhalable for a significant duration of time. These tiny particles accumulate gradually over time throughout the human body and that this buildup is linked to a variety of immune-related malfunctions which eventually lead to chronic disease of many types. 


Health Repercussions


Environment is estimated to play a role in up to 90% of chronic and autoimmune disease. The other 10% is likely genetic. This leaves a whole lot of room for environmental factors such as air pollution to leave a mark on health and wellbeing. 


Adult Health


Early research on air toxicity has shown that chronic degenerative diseases like Alzheimer’s may be particularly environmentally linked. Adults exposed to polluted air have been shown to be more likely to display signs of memory decline. In many cases these declines eventually lead to dementia. Whatsmore, higher levels of exposure to airborne toxins revealed increased likelihood of memory issues. In other words, the more pollution you are exposed to, the greater its impact is on your cognitive capacities (Trank, 2020).


Another study found that exposure to particulate matter such as sulfur dioxide and nitrogen dioxide contributes to cognitive degeneration in aging adults. Males with lower levels of education (which resulted in low baseline verbal and math scores) were particularly affected. This suggests that education plays a protective role in brain health over the lifespan. Gender differences in cognitive decline were attributed to male’s lower levels of white matter. Given white matter is particularly susceptible to the effects of toxic air, it is likely men who have less white matter to begin with see the greatest losses (Gibbens, 2020). 


Developmental Health


Research from 2020 reveals that the elderly individuals who have had lifetime-exposure to toxins are not the only ones being affected by air toxicity. Children can also be affected by air pollution whether it be in-utero or in childhood. Exposure to polluted air and particulate matter has been found to be highly associated with increased vulnerability to neurodevelopmental disorders, poor mental health and even cognitive defects in the general population (Boda, Rigamonti, & Bollati, 2020).


Evidence suggests particulate matter affects embryonic development by disrupting brain growth and maturation. For instance it has been observed that boys exposed to high levels of particulate matter between gestation and the age of 7 exhibit lower levels of working memory (Offord, 2019). A 2014 study seems to confirm this, as children with higher prenatal exposure to polycyclic aromatic hydrocarbons (a byproduct of burning fossil fuels), was associated with increased risk for behavioral and cognitive disorders, including ADHD. For these reasons, expecting mothers should be just as concerned with the air they breathe as they are with the foods they eat. 


School Age Children


Particulate matter can also affect children by interfering with normal cellular processes involved in normative learning and development. Research shows particulate matter interferes with the production of new neurons and glial cells. It also affects myelination (the growth of myelin, the protective sleeve around a neuron which generates in Multiple Sclerosis) and synaptogenesis (the formation of new connections between brain cells) which takes place while learning (Boda, Rigamonti, & Bollati, 2020). This indicates air quality during childhood, particularly in and around learning environments like schools, daycares, and after school care programs is essential to healthy development of the brain and to learning. 




Research on the effects of air pollution on the adolescent brain seems to indicate that it doesn’t take many years of exposure to airborne toxins to cause disease. A 2016 study revealed higher levels of prescription psychiatric medication prescribed to those living in areas with high exposure to nitrogen dioxide. 


Additionally, a 2019 study showed that exposure to air pollution during childhood was linked to higher levels of depression and anxiety in pre-teens. A UK study found higher rates of psychotic episodes in those teens which had grown up with the highest level of exposure to nitrogen dioxide and particulate matter (Offord, 2019). 


Adult learning is similarly inhibited by particulate matter, but over time airborne toxins can begin to cause more severe outcomes such as disease. While the exact processes are currently the subject of much research, the mechanisms are beginning to be uncovered. Air pollution has been linked to chronic inflammation, microglial cell activation, cytokine storms, epigenetic alterations, and ultimately, chronic disease and cellular death. 




There are several ways which airborne toxins are thought to gain access to and affect brain health:


  1. The olfactory bulb

The olfactory bulb is the only acces point to the brain not protected by the blood-brain barrier. Contaminants smaller than 2.5 micrometers which are inhaled through the nose may reach the olfactory cortex and therefore the rest of the brain via the olfactory bulb.


  1. The lungs

Toxins inhaled into the lungs are absorbed into the bloodstream, and some may cross the blood-brain barrier (Offord, 2019). The surface area of the lungs is as expansive as the size of the tennis court, so there’s a ton of area for toxins to become stuck and absorbed. We breathe in up to 10,000 liters of air a day, containing countless contaminants (Gibbens, 2020). 


  1. The gut

Pollutants also find their way into the gut via swallowed air, and are absorbed into organ tissues and the bloodstream. Exposure to air pollutants also alters the gut microbiome, which is linked to cognitive function and brain health. By decreasing the diversity of gut flora, airborne toxins compromise brain health even further (Offord, 2019). 


Once in the brain, these pesky toxic particles cause all manner of health-malfunctions including inflammation as the body attempts to combat the intruder. It is also theorized that toxins from the air cause the activation of microglial cells in the central nervous system. This  further contributes to chronic inflammation that occurs in a number of chronic diseases, including dementia, parkinsons, cancer, stroke, and heart disease (Wu, et al., 2020). 


Unrestrained inflammation and microglial activation are two examples of how the immune system becomes overrun in it’s attempt to rid the body of toxins. Research also indicates these pollutants can lead to oxidative stress. This condition occurs when the immune system is unable to counteract the effects of free radicals and detoxify the body via neutralization by antioxidants. Studies show that pollutants from the air may cause cellular malfunctions in the mitochondria, which are the powerhouses of the cells (Chew, Kolosowska, Saveleva, Malm, & Kanninen, 2020). By  doing so, pollutants undermine the energy source of immune cells, lowering the body’s ability to fight inflammation and infection. 


Additionally, excess inflammation can lead to cytokine storms, which is a severe immune reaction. During a cytokine storm, the body introduces excess cytokines into the blood too quickly. While cytokines are immune cells which play an important role in normal immune responses when in small amounts, high levels of cytokines, on the other hand, can be harmful and cause cell death. 


Epigenetic (gene expression) changes result from airborne toxin exposure. This occurs when a pollutant causes a gene expression to turn on or off. Doing so alters the body’s function according to the responsibility of that gene. For instance, research has focused on epigenetic alterations which switch on or off the gene which contributes to vulnerability to cancerous tumors. These switches in genetic expression are powerful and can be passed down through multiple generations, or altered by lifestyle. 


Studies also link air pollution to chronic disease beyond the brain, including heart disease and diabetes. As mentioned, air pollution can enter the bloodstream in a number of ways, at which point it is pumped throughout the body, and filtered through the heart. Pollutants in the blood trigger inflammation in the blood vessels, which over time contributes to plaque buildup in the arteries and eventually heart disease. Similarly, the gut is the site where a great deal of pollutants can build up. Causing dysregulation and contributing to an inability to process sugars and produce insulin (Gibbens, 2020). 


What can we do about it?


The fact that it’s estimated that the environment plays a role in up to 90% of chronic and autoimmune disease, it can seem incredibly daunting given air pollution is a global issue, as well as an individual one. However, it is important and salient to note that just as the role of the environment in disease varies within a global population, it is also flexible within an individual. This is to say, we can affect our health outcomes both for ourselves and others depending on how we care for the quality of our air. 


Thus, this once daunting statistic can then be reinterpreted that the environment we expose ourselves to can affect up to 90% of our disease outcome. This is a powerful statistic because it indicates that controlling the toxicity of our environment gives us greater control over our lifetime of wellbeing. 


As individuals we can affect the toxicity of our environment. Indoor air quality can be improved by taking off your shoes and wiping your feet when coming indoors, using air filters and dehumidifiers to offset mold in areas of high humidity, dusting with cleaning products made with essential oils, cultivating and caring for indoor plants, and purchasing used furniture to avoid off gassing. A pranayama (breath) practice regularly can help clear the lungs of toxins and promote respiratory health and immunity. Regular detoxing helps to clear the lymphatic and lymphatic systems and also helps to give your immune system a leg up against airborne pollution. 


Outdoor air requires broader community action — advocating for legislation and public policy which pushes the world toward a reduced carbon footprint, supporting organic agriculture, and reforesting are all efforts which contribute to keeping our outdoor air fit for breathing (Trank, 2020). One study found that silver birch, elder, and yew trees were particularly effective at soaking up fine particulate matter, so planting these trees in and around your space will also help to clear your air (Offord 2019). Other research suggests that planting these trees around educational facilities might enhance developmental and learning outcomes. 


Given air cannot be cordoned off, the quality of it is a matter of global significance. Similar to the once unbridled proliferation of cigarette companies for profit at the expense of public health, so many of the sources of air pollution are steeped in big money and politics. 


However, science and public advocacy are powerful tools in curbing pollution and greed, while simultaneously taking back our air quality and our health and wellbeing for ourselves and generations to come. 


It’s more than just what’s in the air


Air isn’t the only source of contemporary toxins which alter brain health! Water, soil, food, personal care products, buildings, cleaning products, and even medicines have potentially life-altering toxins in them.


To learn more about these pollutants and toxins as well as how to protect yourself and your loved ones from their harmful effects for a lifetime of clear thinking, join us for the Prevent Alzheimer’s through Yoga Online Program.




Offord, C. (2019). Air Pollution May Damage People’s Brains. The Scientist.


Chew, S., Kolosowska, N., Saveleva, L., Malm, T., & Kanninen, K. M. (2020). Impairment of mitochondrial function by particulate matter: Implications for the brain. Neurochemistry international, 135, 104694.


Boda, E., Rigamonti, A. E., & Bollati, V. (2020). Understanding the effects of air pollution on neurogenesis and gliogenesis in the growing and adult brain. Current Opinion in Pharmacology, 50, 61-66.


Wu, A. H., Wu, J., Tseng, C., Yang, J., Shariff-Marco, S., Fruin, S., … & Jain, J. (2020). Association between outdoor air pollution and risk of malignant and benign brain tumors: The Multiethnic Cohort Study. JNCI Cancer Spectrum.


Gibbens, S. (2020). Air Pollution Robs Us of Our Smarts and Our Lungs. National Geographic.


Trank, A. (2020). Toxins and Your Brain. Prevent Alzheimers Through Yoga Online. Vimeo. 

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