Exposure Modeling

Exposure Modeling

Contaminant Exposure Modeling using CFD (Computational Fluid Dynamics)

As professional industrial hygiene consultants specializing in exposure assessment and risk characterization, C&IH utilizes an assortment of modeling technologies to characterize workplace and community exposures. One such modeling tool is computational fluid dynamics (CFD), a three-dimensional computer modeling technology that simulates an airborne contaminant’s distribution under site-specific and client-selectable conditions.

C&IH applies computational fluid dynamics to create models for predicting how a contaminant with fluid-like properties, such as water, air, or gas, will travel under specified conditions. Examples of variable conditions include air velocity, pressure, temperature, and humidity. Contaminant properties can also be specified, including particle size, chemical composition, and mass. In the performance of an exposure assessment, these variable inputs enable CFD to be used as a valuable tool for airborne contaminant emission and dispersion modeling; specifically, to test, validate, replicate, or predict a contaminant’s transport and pathway.

Air Dispersion Modeling and Exposure Assessment

Airflow modeling using CFD creates an effective visual validation tool for communicating and managing occupational health exposures. Examples include:

  • Validate existing air sampling data of indoor or outdoor air contaminant emissions including gases, fibers, and particles
  • Generate exposure modeling data when air sampling is not possible or has limitations
  • Model contaminant dispersion characteristics of historical jobsites and workplace activities (when air monitoring is no longer possible) to understand past exposure
  • Characterize community exposures through plume modeling of outdoor contaminant dispersion

Ventilation Modeling and Engineering Controls

In addition to CFD’s role in supporting exposure assessment projects, the air flow modeling capabilities of CFD also serve as a valuable tool in the design of engineering controls. Examples include:

  • Evaluate workplace ventilation performance criteria for specified applications such as laboratory and industrial process environments
  • Verify the performance characteristics of different stack designs and placement relative to plume emission and dispersion (while adjusting variables such as wind velocity and direction, ground cover, adjacent buildings, solar loading, fresh air intake locations, etc.) to optimize stack performance
  • Model indoor air quality conditions such as thermal comfort and air circulation to identify the effectiveness and limitations of a proposed ventilation system change before it is built or modified
  • Validate the performance of proposed ventilation-oriented engineering controls such as dilution and local exhaust ventilation, laboratory hoods, and other exposure mitigation systems before implementation to analyze and maximize system efficacy

Air flow modeling using computational fluid dynamics can be a valuable tool in support of various industrial hygiene related projects. C&IH retains staff solely dedicated to CFD. Our modeling staff collaborates with clients to define specific goals and discuss criteria for each CFD model. C&IH can also incorporate historical data sets, on-site measurements, and field data collection to validate models generated. Specific aspects of site investigations may include air monitoring, evaluation of indoor/outdoor spaces, air exchange rates, spatial anomalies, source concentration and generation rate, distances from source contaminant, and inspection of ventilation schematics and design.