During the week of Christmas, Pittsburg, PA experienced an unusual heavy set of particular matter created by a temperature inversion that resulted in the trapping of pollution closer to the Earth’s surface. A temperature inversion is created when a mass of warmer air sits on top of and trapping of a mass of colder air, therefore preventing polluted air from rising. The event continued for six consecutive days in Pittsburgh. Rising temperatures in the winter could mean that similar “Super Pollution Events” involving dangerous levels of particulate matter in the air might become more common. Read More.