An advanced indoor air quality analysis system is available free of charge via download at the National Institute of Standards and Technology (NIST) website. Designed to help engineers determine indoor air contaminant concentrations, occupant exposures, and multi-zone airflows or patterns, the program predicts contaminant concentrations--the dispersal of airborne contaminants transported by airflows and transformed by a variety of processes including chemical and radio-chemical transformation, adsorption and desorption to building materials, filtration, and deposition to building surfaces; and/or personal exposure--and thus the prediction of exposure of building occupants to airborne contaminants for eventual risk assessment. Dispersion is calculated not just for mechanical ventilation, but also wind pressures on the exterior envelope and buoyancy effects from interior/exterior temperature differences.

Because the NIST is an agency of the U.S. Department of Commerce, the experimental system, called COTAM, was developed by federal government employees “in the course of their official duties.” Pursuant to Title 17 Section 105 of the United States Code, the software is not subject to copyright protection and is in the public domain. You can obtain a copy by clicking here.

CONTAM can be used to determine the indoor air quality performance of buildings before they are constructed and occupied, to investigate the impacts of various design decisions related to ventilation system design and building material selection, to evaluate indoor air quality control technologies, and to assess the indoor air quality performance of existing buildings. Predicted contaminant concentrations can also be used to estimate personal exposure based on occupancy patterns. Exposure estimates can then be compared for different assumptions of ventilation rates and source strengths.

For a highly detailed and technical description of CONTAM, click on the following link to view the User Guide and Program Documentation .