Spatio-temporal variation and deposition of fine and coarse particles during the Commonwealth Games in Delhi

The Indian Government implemented the project "System of Air quality Forecasting And Research (SAFAR)" for the "Commonwealth Games" 2010 in Delhi. It was adopted by the Global Urban Research Meteorology and Environment of World Meteorological Organization as its pilot project. We used data from a dense network of stations built over 2500 km²in Delhi under the SAFAR project to investigate temporal and spatial variations of fine (PM_2.5) and coarse (PM_10-2.5) particles, and discuss their deposition and the airborne mass fractions that were retained after a certain amount of time. The 24-hour coarse particle (PM_10-2.5) means during the Games period were always above the National Ambient Air Quality Standard NAAQS (100 μg/m³) at all the sites except the airport. In still air, initial PM_10-2.5can reach below 50 μg/m³by deposition in an hour. The 24-hour PM_2.5means reveal that they were either around or below the NAAQS (60 μg/m³) at some sport complexes, whereas they fluctuated between 60 and 80 μg/m³at the other sites.