Increasing amounts of research indicate that air pollution is linked to accelerated brain aging. That’s the bad news. The good news is that there is also research underscoring the potential health benefits of air purifiers in homes where older adults live.
Can air pollution can accelerate cognitive decline?
A study presented at the annual meeting of the Gerontological Society of America concluded that exposure to high levels of air pollution does indeed age the brain prematurely. The study was conducted by a team of scientists at the University of Southern California’s Davis School of Gerontology.1
The researchers studied cognitive test scores of more than 15,000 adults over 50 years old and mapped their test scores with air pollution concentration maps. The results showed that the brains of those living in the areas of the highest pollution aged three years faster than those who lived in the areas of least pollution.
The brains of those living in the areas of the highest pollution aged three years faster than those who lived in the areas of least pollution.
This study resonates with the findings of research from the Rush University Medical Center. Their study reported a link between exposure to fine air pollution particles and cognitive decline.2 What was not included in the study were ultrafine particles (UFPs) - the most abundant and most dangerous particles. These are also the most difficult to measure.
In case you need a quick refresher of what fine and ultrafine particles are, see below:
- Fine particles (PM2.5): Particles ranging in diameter between 0.1 and 2.5 microns. For comparison, the diameter of a single human hair ranges from 17 to 181 microns. When inhaled, these particles can lodge in lung tissue, triggering respiratory illnesses such as asthma, bronchitis, and emphysema. In addition to cognitive decline, PM2.5 exposure has been linked to increasing the potential for cardiovascular problems, such as arrhythmic heartbeats and heart attacks. PM2.5 represent about 9% of all airborne particles.
- Ultrafine particles (UFPs): Particles smaller than 0.1 microns in diameter. About 90% of all airborne particles are this size. Not only are UFPs the most numerous of airborne particles, but they are also the most dangerous to your health. The tiny size of ultrafine particles enables them to be easily inhaled, deposited into the lungs and absorbed directly into the bloodstream. From there, they travel with your bloodstream to all vital organs, including your brain. UFPs may also be able to cross the blood-brain barrier.
PM2.5 and brain aging
One large-scale study found that long-term exposure to higher-than-normal levels of PM2.5 coincided with smaller-than-normal gray and white matter volumes in the frontal lobe, which plays an important role for thinking, decision-making, and planning.3 Another study found that for every 3.5 micrograms of PM2.5 per cubic meter of air, white matter (nerve fibers that connect different brain regions) decreased by 6 cubic centimeters.4
The researchers collected the data of over 3,000 women aged between 65 and 79 with the condition that no participant had any medical history of cognitive decline. The study found that the elderly women that happened to live in areas where the concentration of particulate matter was higher than the standard considered safe by the U.S. EPA (Environmental Protection Agency) were 81% more likely to develop a condition affecting their brains.
A study comprising 31,000 Chinese citizens looked at math and verbal test scores and matched them with air quality data between 2010 and 2014. The researchers found cognitive decline was substantially higher in areas where pollution was severe, even with the data being controlled for the natural cognitive decline that happens with age.5
Ultrafine particles and brain aging
By far the least studied air pollutant is ultrafine particulate matter. These particles can be as small as 0.003 microns – that’s ten times smaller than a virus. As research does surface about the effects of ultrafine particles on cognition, it becomes clearer that this is an area which warrants greater attention.
For example, according to a study published in the medical journal Translational Psychiatry, research illustrates that there is a connection between ultrafine air pollutants and neurological disorders and cognitive decline markers, such as memory disorders or defective reasoning.6
What you can do now to protect your brain
A HEPA air purifier can remove air pollution particles from the air and offer protection indoors, a point made by a researcher involved with the Rush University study. “If you have central air or forced air heating, you can install HEPA filtration,” Weuve reportedly said. “That can help keep the air in your home clear.”
But HEPA filters are not proven to catch the most dangerous and most abundant particles – ultrafines. IQAir’s patented HyperHEPA technology is certified to stop ultrafines.
- Monitor your Indoor Air Quality (IAQ). AirVisual Pro by IQAir lets you monitor pollutants in your indoor and outdoor air so that you know exactly when air quality is bad. You can also download the free AirVisual app and see the air quality from your closest outdoor air monitoring station.
- Avoid unnecessary exposure at home. Avoid unnecessary exposure by using a high-performance air purifier, such as the IQAir HealthPro® Plus room air purifier or the Perfect 16® whole-house air purifier.
- Use a high-powered personal air purifier, such as the IQAir Atem® Desk. If you are often stuck in traffic, try the Atem® Car air purifier.
- Reduce air pollution. Conserving energy, recycling, driving less or driving low-polluting vehicles - the choices you make can help reduce air pollution for everyone.
Don’t get overwhelmed by the seemingly impossible problem of air pollution. You can take steps to protect yourself and make your own small contribution to help limit your carbon footprint.
Air Quality Life is brought to you by The IQAir Group, the world’s leading innovator of Indoor Air Quality solutions since 1963. This online publication is designed to educate and inform the public about the latest research and news affecting indoor and outdoor air quality.
 Ailshire JA, et al. (2014). Fine particulate matter air pollution and cognitive function among older US adults. DOI: 10.1093/aje/kwu155
 Weuve J, et al. (2012). Exposure to particulate air pollution and cognitive decline in older women. DOI: 10.1001/archinternmed.2011.683
 Bert PP, et al. (2018). The effects of air pollution on the brain: A review of studies interfacing environmental epidemiology and neuroimaging. DOI: 10.1007/s40572-018-0209-9
 Cacciottolo M, et al. (2017). Particulate air pollutants, APOE alleles and their contributions to cognitive impairment in older women and to amyloidogenesis in experimental models. DOI: 10.1038/tp.2016.280
 Zhang X, et al. (2018). The impact of exposure to air pollution on cognitive performance. DOI: 10.1073/pnas.1809474115
 Genc S, et al. (2012). The adverse effects of air pollution on the nervous system. DOI: 10.1155/2012/782462