According to a recent report by the Health Effects Institute,1 95 percent of the world live in areas where the pollution levels are higher than deemed safe by the World Health Organization (WHO). This makes air pollution the fourth largest cause of death, following high blood pressure, diet and smoking.
Fine particulate matter (PM) concentration exceeds 10 micrograms per meters cubed (ug/m3) for 95 percent of the world, and nearly 60 percent live in areas where the PM exceeds even the least stringent WHO air quality target of 35 ug/m3.2 Fine PM measuring less than 2.5 micrograms (PM2.5) is one indicator of outdoor pollution levels.
Experts estimate exposure to PM2.5 contributes to more than 6 million deaths worldwide and plays a large role in increasing the risk of stroke, lung cancer and heart attack. Although many developed countries have made significant moves toward reducing air pollution, developing countries have fallen further behind as they struggle for economic growth.3
Bob O’Keefe, vice president of the Health Effects Institute, believes there’s reason for optimism, though, as both China and India are taking steps to reduce pollution.4 Although the physical effects of air pollution are well-known, a recent study5 demonstrates it may cause a large reduction in intelligence, indicating damage of toxic air is far more significant than previously believed.
Air Pollution Damages Intelligence
Although data was collected on 20,000 people living in China, the researchers believe the findings are relevant to the entire world. They found6 language and arithmetic skills were affected, with the average impact on those tested equivalent to losing one year of education.
However, a member of the research team believes the effects may be even worse for the elderly and for those with a low education level. Calculating the loss in those individuals may increase damage to several years. The study authors concluded:7
“The damage on the aging brain by air pollution likely imposes substantial health and economic costs, considering that cognitive functioning is critical for the elderly for both running daily errands and making high-stake decisions.”
According to this study, the longer people were exposed, the greater the damage. Language skills were the most dramatically affected, in men more than women. Researchers monitored individuals for more than four years.8 Other studies have found air pollution harms cognitive performance in students. However, this is the first to examine individuals of all ages and the differences between men and women.
Data from other studies have linked air pollution to high mortality in those who suffer mental disorders.9 It’s also been found to raise the risk of mental illness in children,10 and those living near busy roads have an increased risk of dementia.11
According to researcher Derek Ho, Ph.D., from Hong Kong Polytechnic University, air pollution likely affects cognition because “high air pollution can potentially be associated with oxidative stress, neuroinflammation and neurodegeneration of humans.”12
Another member of the research team, Xi Chen at Yale School of Public Health, believes air pollution is most likely the cause of loss of intelligence rather than simply being correlated.
The team noted air pollution has a short-term impact on intelligence as well, which could have significant consequences for students who have to take crucial exams on polluted days. Dr. Aarash Saleh, from Doctors Against Diesel campaign, remarked:13
“This study adds to the concerning bank of evidence showing that exposure to air pollution can worsen our cognitive function. Road traffic is the biggest contributor to air pollution in residential areas and the government needs to act urgently to remove heavily-polluting vehicles from our roads.”
Another study, conducted over 20 years in Sweden, demonstrated those with asthma — a potential health risk with exposure to air pollutants — were three and a half times more likely to leave school by the age of 16 and twice as likely to drop out of the university. This suggests exposure to pollutants at a young age may impact the future education and jobs of these children.