") air pollution has recently been recognized as a risk factor for . ... Fine particulate matter may affect cognitive function via as a result of systemic inflammation or following lung irritation. ... It has also been proposed that the smallest particles, often coated with neurotoxic chemicals, ... can enter the brain through the or cross the . ... Unlike many other common risk factors for dementia (eg, hypertension, stroke, and ), exposures to air pollution can be modified at the population level, making it a prime target for large-scale prevention efforts."