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CONTAM Particle Distribution Calculator

A Web Application to develop particle size distributions for use in CONTAM.

Web Application


  • Number of Modes - The number of Modes used to create the particle distribution.
  • Bins - There are two methods to create the bins of particles: Auto and User-Defined. The Auto method creates equally sized bins ranging from the smallest particle diameter to the largest particle diameter. The User-Defined method allows you to define the particle size for each bin and set the number of particles in each bin.
  • Number of Bins - number of size bins (bins are defined by their midpoint diameter)
  • Smallest Particle Diameter - the particle diameter to use as the midpoint diameter for the bin with the smallest diameter.
  • Largest Particle Diameter - the particle diameter to use as the midpoint diameter for the bin with the largest diameter.
  • Define User Bins - click this button to open a dialog to define a custom set of bins. This button is only activated if the User-Defined bins option is selected above.
  • ρair - the density of air.
  • ρparticles - the density of the particles.
  • Modes - When using the Auto Bins mode three modes can be defined. These modes are combined to create a single distribution of particles.
  • Distribution Type - Each mode can have either a normal or log-normal distribution type.
  • µg - Each mode includes a mean particle diameter or geometric mean particle diameter to define the distribution.
  • σg - Each mode includes a standard deviation or geometric standard deviation to define the distribution.
  • Total N - Each mode includes the total number of particles in the distribution.


  • CONTAM Contaminant Library file (LB0) - A CONTAM Contaminant Library file is generated. This library includes a particle species for each bin whose default concentration is set to that defined by the distribution. Once these species are imported into CONTAM, the initial concentrations can be utilized as ambient concentrations. Also multiple library files can be created, e.g., one for ambient and one for indoors. Import the “indoor” library, initialize interior zones to default, then import the ambient library to set the ambient values for use in the simulation.
  • CONTAM Outdoor Contaminant file (CTM) - A CONTAM Outdoor Contaminant file can be generated to cover a single day. The particle concentration values in the CTM file created by the Particle Distribution Calculator will constant at the defined distribution levels for the entire day. The CTM file can be modified to cover up to one year as is the case for any CTM file.


Jacobson, M.Z. (2005) Fundamentals of Atmospheric Modeling. Second ed. New York: Cambridge University Press. ISBN-10: 0521548659 | ISBN-13: 978-0521548656

Created March 9, 2018, Updated August 11, 2020