The quality of the air does not only affect our physical health. According to a new study, air pollution can even affect the way we think.
The harmful effect of pollution on health has been known for a long time. It has been classified as a carcinogen by the World Health Organization (WHO) since 2013 and is linked in part to cases of dementia and Alzheimer’s disease. Particles and gases from factories and exhaust pipes also play a role in the onset of asthma and diseases of the heart and lungs.
However, the negative impacts of air quality may well exceed the field of physical health and affect mental health. According to a new study , air quality can influence our ability to think, and also affect the results of certain types of exams.
To come to this conclusion, researchers retrieved socioeconomic data as well as cognitive test scores from tens of thousands of individuals across China between 2010 and 2014.
They were able to compare this information with satellite survey data and ground stations measuring air quality across China during this same period.
Knowledge tests included 24 mathematics and 34 vocabulary questions. Atmospheric data included daily measurements of three of the country’s main pollutants: nitrogen dioxide, sulfur dioxide and nanoparticle levels in the air.
By separating the groups according to their age and exposure time, researchers were able to evaluate the effect of atmospheric pollutants on test performance.
Knowledge in the air
By comparing the test results with the exposure time to poor air quality, the researchers found that the pollution was related to a significant drop in performance on the knowledge tests. This drop affected vocabulary questions more than mathematics exercises.
The study also shows that the negative effect of pollution increases with the time of exposure and is greater if the person is elderly. In addition, the phenomenon targets more men, people with less education and those who often work outside.
However, although researchers have shown this link, their results failed to show that pollution was the only cause of this cognitive decline.
Nor did they indicate which air pollutant was responsible for the most significant damage, especially since carbon dioxide and carbon monoxide and the larger suspended particles were missing from the assessment.
Nevertheless, these conclusions are consistent with what other studies have suggested in the past. In addition, this is the first time that a link between pollution and cognitive performance has been observed in so many people and measured by age group and sex.
The results of this study, while specific to China, can provide insight into the effect of pollution on humans in several major cities around the world. According to the World Health Organization, poor air quality is responsible for more than 7 million deaths a year.
Human studies have not yet provided clear explanations for the effect of pollution on the brain. However, animal studies have shown that this organ can be affected in two ways.
First, tiny pollutants may be able to travel to the brain and cause damage, either through direct toxicity or by triggering inflammatory responses. They could also accumulate in the lungs and cause systemic inflammation with harmful effects on the nervous system.