From the article: “All participants were given medical exams at the beginning of the study as well as cognitive tests to measure memory, language skills and executive function, which involves thinking skills like organizing, planning and completing tasks. The group from the Washington-Heights-Inwood study of 5,330 participants was followed an average of seven years with six rounds of follow-up testing every 18 months to two years. The researchers found that in the Washington Heights-Inwood group, people with greater exposure to higher levels of air pollution had lower scores on the tests at the beginning of the study and more rapid rates of decline. Exposure to nitrogen dioxide was linked to an accelerated rate of cognitive decline comparable to one year of aging. Results were similar for fine and respirable particulate matter.”