----------------------------------------------------------------------------------------------------------

What Are We Learning from Satellites About the Quality of Air We Breathe?

  ----------------------------------------------------------------------------------------------------------

A series of satellite instruments of increasing sophistication have been launched since 1970 to monitor the composition of our atmosphere. In the early years the focus was on the study of the ozone depletion problem that reveals itself yearly as a 'hole" in the ozone layer over Antarctica in spring. With the gradual phase out of the ozone depleting substances the ozone layer is fortunately well on its path to full recovery in several decades. However, with increasing population and industrial activity the quality of the air we breathe is degrading rapidly in the developing world, though it has improved somewhat in the US due to stringent regulation. I will show images from the Dutch-Finnish built OMI instrument that has been flying on a NASA satellite since July 2004 to highlight what are we learning about global air quality from space. This instrument measures several key atmospheric pollutants that have been classified by the US Environmental Protection Agency (EPA) as Criteria Pollutants. These include ozone, nitrogen dioxide, sulfur dioxide, and particulate matters, which are also known as aerosols. A key contribution that satellites have made is to show very vividly how our atmosphere acts a mixing bowl in which man-made and natural pollutants mix and photo-chemically convert into new chemical species. These pollutants are then transported far away from their source by prevailing winds affecting air quality globally.