Papers such as this are quite revealing. “Many dementias are often preceded by a long period of cognitive decline. But we don’t know very much about how to prevent or delay dementia,” Weuve says. If it turns out that air pollution does contribute to cognitive decline and the onset of dementia, the finding could offer a tantalizing new way to think about preventing disease. “Air pollution is something that we can intervene on as a society at large, through technology, regulation and policy,” she says.