Intake fraction (iF) is a measurement used to describe the mass of pollution inhaled for some quantity of pollution emitted to the atmosphere. Scientists, engineers, and public health officials use this metric in the process of evaluating the exposure consequences attributable to a given emissions source.
The map above shows iF measurements for particulate matter taken from the Air Pollution Emission Experiments and Policy model. Notice that differences in proximate population density and local meteorology can produce substantial variability in iFs.