Air quality

Region/Country	Description
US	A meteorological situation in which there is a major buildup of air pollution in the atmosphere. This usually occurs when the same air mass is parked over the same area for several days. During this time, the light winds cannot "cleanse" the buildup of smoke, dust, gases, and other industrial air pollution.
CA	Air Quality Advisory is issued when air quality is expected to be poor.
EU	Air quality is low, e.g. due to air stagnation.