Facility owners that may produce emissions of toxic air contaminants (TAC) and federal hazardous air pollutants (HAP) require expertise in conducting regulatory review, applicability assessment and identification of compounds of concern as defined in various jurisdictions and using available environmental, occupational and industrial safety and health standards.

Geosyntec has experience in TAC and HAP quantification via emission estimating, measurement, and developing or referencing profiles of TAC in common gas or liquids – according to federal, state and industrial standards and methodologies. Geosyntec's scientists and engineers employ advanced solutions to identify emission stream characteristics from stationary sources such as factories, refineries, and power plants, as well as from indoor sources, such as building materials and industrial operations.

These compounds of concern can have health and ecological impacts. To understand the impacts, Geosyntec has experts in estimating pollutant concentrations and the extent of those impacts via air dispersion modelling in addition to or in lieu of measurement. Modelling allows determination of how much and where impacts may be occurring using advanced software and GIS mapping techniques. Our modelling experts use tools such as U.S. EPA's AERMOD as well as other release models appropriate for the situation.

Health impacts are often characterized in a Health Risk Assessment (HRA), which can characterize risk of cancer and non-cancer (acute or chronic) risk to the general population or individual 'receptors' or sensitive populations. Geosyntec experts develop and use protocols and methods approved by health officials and in some cases, models (e.g., HARP2 program in California) to undertake hazard identification, exposure assessment, and dose-response assessment. We follow recommended guidelines and tailor the assessment to each specific situation. We also take care in presenting the results of HRAs for context and understanding of our clients, agency reviewers and public disclosure. Often this involves stakeholder engagement planning and risk communication strategies, where we team with our clients and specialists to advise and implement on the plans.

Geosyntec's air quality practitioners, engineers, scientists and toxicologists offer decades of experience advising on risk reduction strategies and recommend actions and alternatives to control or mitigate adverse environmental and ecological impacts of TAC and HAP emissions. Geosyntec practitioners have expertise in process design as well as air pollution control technology design that enables us to develop strategic approaches to complex, multi-pollutant emission issues. We routinely determine the performance and cost of air pollution control techniques designed to reduce or eliminate emissions of air toxics from industrial and commercial sources. We assist in selecting and implementing the best mitigation and control systems and provide permitting assistance under federal, state, and local air construction and operating permit programs.