U.S. scientists say they\'ve developed a fleet of portable pollution sensors that can be deployed to report air quality in real time to people\'s smartphones. Researchers at the University of California, San Diego, say their CitiSense sensors, in delivering real-time data to users\' cell phones and home computers, would be particularly useful to people suffering from chronic conditions such as asthma who need to avoid exposure to pollutants. Just 100 of the sensors deployed in a fairly large area could generate a wealth of data, they said. \"We want to get more data and better data, which we can provide to the public,\" said William Griswold, a computer science professor at UC San Diego and the lead investigator on the project. \"We are making the invisible visible,\" he said in a university release Tuesday. The CitiSense sensors detect ozone, nitrogen dioxide and carbon monoxide, the most common pollutants emitted by cars and trucks, and smartphones can display the readings using a color-coded scale for air quality based on the air quality ratings from the Environmental Protection Agency, from green (good) to purple (hazardous). In a test researchers provided the sensors -- small enough to be carried in a backpack -- for four weeks to a total of 30 users, including commuters at UC San Diego. The ultimate goal of CitiSense, its developers said, is to build and deploy a wireless network in which hundreds of small environmental sensors carried by the public would use cell phones to send data to central computers where it will be analyzed and delivered to individuals, public health agencies and the community at large.