The study asked 34,000 English citizens from several of England’s authority districts to remember 10 words in a word recall test. The researchers compared the memories of participants living in England’s polluted areas to those living in the cleanest areas. The researchers also accounted for other factors that could influence people’s memories, such as health, age, ethnicity, education level, family life and employment status.
The study found that compared to those who live in clean areas, those living in polluted areas experienced greater memory loss. The researchers were specifically testing for nitrogen dioxide (NO2) and air particulate (PM10) pollutants.
According to Air Quality Now, NO2 is emitted through the burning of fuel and has “detrimental effects to the bronchial system.” Airborne particulate matter like PM10, on the other hand, consists of extremely small particles usually emitted from diesel vehicles that can “penetrate deep into the lungs.”
Comparing the memory of those living in England's most-polluted areas with those in the cleanest, the study found that a person breathing in more pollutants had memory loss equivalent to someone 10 years older than them in the clean area. In other words, a 50-year-old living in a polluted area had the same memory performance as a 60-year-old living in an area with cleaner air.
However, the researchers note that the study does not conclusively determine a link between pollutants and memory loss.
“There is a little prior evidence of a negative association between levels of traffic pollution and memory using data on elderly individuals and in children. But almost all research in human studies on this topic has been based on elementary correlations and not on nationally representative samples of individuals in a country. We have tried to solve these two problems in our study,” lead researcher Nattavudh Powdthavee is quoted as saying by Air Quality News.
A new report released by the European Environment Agency Wednesday also found that poor air quality was responsible for the premature deaths of about 400,000 people in Europe, calling air pollution the “most important environmental risk to human health” today. Although the report did note that the level of harmful pollutants in some European cities were on the decline, the reduction is still not enough to meet EU standards.