EAST COAST TOAST:True-color shots from NASA's Moderate-Resolution Imaging Spectroradiometer (MODIS) satellite overlaid with Google Earth maps show the haze and smoke from the Evans Road fire in North Carolina on June 13, 2008, U.M.B.C.'s Hoff says. The smoke stretches northward through Virginia toward Washington, D.C.
The color of the dots on the map correspond to the EPA's Air Quality Index (AQI), the system of categorizing relative air quality. The four AQI color categories, sometimes called codes, seen here include green (good), yellow (moderate), orange (unhealthy for sensitive groups—meaning children, the elderly and those with respiratory ailments), and red (unhealthy for all). The scale also has two extreme categories: purple, and rarely seen maroon, which only comes up in forest fire situations, says Alison Davis, a senior adviser for public affairs at EPA's Office of Air Quality Planning & Standards. See the EPA-led interagency AIRNow Web site for more details on the AQI.