Particulate matter in the air, which can come from both natural and anthropogenic sources, can be detrimental to human health. Air quality standards in Europe and elsewhere regulate emission of air pollutants from human sources, but in some locations, particulate matter levels are still high. Among the natural factors that can influence particulate matter concentrations are large-scale atmospheric circulation patterns, such as the North Atlantic Oscillation (NAO). Understanding the relationship between NAO variability and particulate matter can help scientists understand particulate matter trends and potentially predict areas likely to be affected by pollution episodes. This is especially important because climate models suggest that the winter mean state of the NAO is likely to shift in coming years.