People with respiratory problems can get an instant up-to-date local report on a key air pollutant with a new free mobile phone app, its U.S. developers say. MobileAQI (Mobile Air Quality Index), developed at the University of Alabama Huntsville, combines data from satellites operated by NASA and the National Oceanographic and Atmospheric Administration with other pollution estimates to give app users an accurate and reliable report on fine particulates in the air, the researchers said. Fine particulates are defined as particles no bigger than 2.5 microns. \"That is the size that is most efficient at getting into your lungs,\" atmospheric science Professor Udaysankar Nair said. \"The population most at risk is the elderly, especially people with respiratory problems, although this could be of use to children or anyone with serious respiratory problems, such as bad asthma.\" The app, available for both Android and iPhone systems, provides a quick reading on local particulate levels, a university release said, with an estimate of current conditions and air quality forecasts hour-by-hour as much as 24 hours in advance. The app\'s coverage area includes most of the eastern United States from the tip of Florida as far north as Milwaukee and from the Atlantic Ocean as far west as the border between Kansas and Colorado, the researchers said.