Air Pollution Affects Cognition

Summary: Pollution harms mental functions

A study published on February 6th, 2025 (1) shows that tiny air contaminants known as PM2.5, produced by combustion, mostly by burning fossil fuels, can reduce brain cognitive abilities like selective attention and socio-emotional cognition.

In this Article (Index)

• Air contaminants harm cognition
• PM2.5 Particulate Matter
• Keeping safe from air contaminants

Air contaminants harm cognition

A study published on February 6th, by Faherty, Raymond, cFiggans, et al., (2025) (1) revealed that even brief exposure to air pollution can harm cognition and affect brain functioning.

The study involved 26 young adults who were exposed to clean air or air contaminated with high concentrations of particulate matter (PM) for one hour. After completing a series of cognitive tests, they inhaled the clean or tainted air and repeated the tests four hours after inhalation.

The results showed that contaminants in the air reach the brain in a short period and reduce its selective attention and emotion expression discrimination abilities.
However, it didn't significantly affect working memory performance or psychomotor vigilance.

Air Pollution and its harmful effects

Research has shown that air pollution increases the risk of early death, and damages the respiratory and cardiovascular systems (stroke, lung cancer, pneumonia, asthma, and COPD). It is also associated with neurodegenerative diseases such as Alzheimer's, Parkinsons, and multiple sclerosis and decline in cognitive functioning.

PM2.5 Particulate Matter

The study reports that a special type of airborne pollutant, particles smaller than 2.5μm (microns) in diameter is the main cause of harmful health effects. Daily exposure to these air contaminants should not exceed 15 μg/m³ (micrograms per cubic meter) during a 24-hour period, or 5 μg/m³ for annual exposure.

This kind of air pollution is produced by the combustion of fossil fuels in cars, power plants, industrial emissions, natural sources (forest fires), and home heating with oil, wood, or coal. The particles contain sulfates, nitrates, ammonia, carbon black, and fine mineral dust.

You inhale them outdoors and also inside your home.

The cognitive impact of pollution

The study cites research pointing out that "short-term exposure to particulate PM air pollution can temporarily impair several key cognitive functions, including selective attention, switch costs (which are relevant to multitasking), decision-making, processing speed, functional connectivity, and even global cognitive functioning."

Pollution can reach the brain along the olfactory nerve, where the minute particles and the chemicals they contain impact the neurons that sense smells after being inhaled through the nose. Another route is through the lungs, when the polluted air is inhaled it enters the bloodstream in the lungs and then crosses the blood-brain barrier to enter the brain.

Keeping safe from air contaminants

Indoors

The strategy is to keep the external air pollutants out and avoid generating indoor air contamination.

• Keep indoor areas well-ventilated, and use filters that reduce PM2.5 levels.
• Use air purifiers with HEPA filters that block PM2.5 particles. Regularly change them according to the manufacturer's directions.
• Don't smoke indoors.
• Keep your house clean. Regularly clean to eliminate dust and particles from floors and furniture.
• Install a kitchen exhaust fan or hood.
• Don't use unvented combustion equipment indoors (heaters, stoves, grills, fireplaces).
• Have a professional check and maintain your home ventilation and heating system every year.
• Use a wood-burning appliance that meets EPA emission standards.

Outdoors

There are different resources that you can use to monitor outdoor air quality, below are two of them, one for the US, and the other with global data:

• AirNow.gov - Home of the U.S. Air Quality Index
• WAQI.info: World Air Quality Index

Poor outdoor air quality is beyond our control; as individuals, we can't modify global or local air contamination except by medium—to long-term actions like endorsing politicians who support air quality or anti-pollution policies and the climate change agenda. As consumers, consider adopting an environmentally friendlier attitude toward the environment (e-vehicles, cycling more, using public transportation, renewable energy sources, etc.).

Some practical actions when outdoor air quality is poor are:

• Stay indoors in a room with filtered air.
• Limit outdoor exposure.
• Reduce activity levels (slower breathing reduces the uptake of contamination by your lungs.
• Forget scarves, bandanas, or regular face masks, they block large particles, not PM2.5. To block these tiny air pollutants you need disposable respirators like N-95 or P-100. Wear the mask correctly.