If you have ever traveled from the center of a big city to a rural area, or the other way around, one of the starkest contrasts is the change in air quality. Although there have been significant decreases in emissions recently, there are still regions where peaks of air pollution are reported. Leaving the climate catastrophe caused by burning fossil fuels aside for a minute, scientists have recently found that these pollutants also have a direct toll on our brains. 

Take for instance black carbon, a material emitted from gas and diesel engines and coal-fired power plants, and also one of the components of fine particulate matter (PM2.5). In both children and adults, exposure to this pollutant has been associated with poor cognitive abilities over the years. What Xu Gao and their colleagues discovered and demonstrated in a new paper, however, is that even short exposures can also cause significant declines in cognition.

The researchers were part of the Normative Aging Study, a cohort of older men from the greater Boston area. Alongside daily measurements of the levels of both PM2.5 and black carbon, over the period of 28 days, the team conducted two tests on 954 participants: the global cognitive function and Mini-Mental State Examination. They found that higher short-term exposure to PM2.5 reduced scores on both tests, and that even small concentrations of PM2.5 had a large effect. The effects of pollution were less for participants who used nonsteroidal anti-inflammatory drugs such as ibuprofen than for those who did not. 

While we already knew that air pollution has many different adverse effects on our health, this is the first time scientists have shown how these effects can manifest in short-term exposures, to relatively small concentrations of pollutants.