Air Quality Modeling - Does your project require air dispersion modelling?

Who conducts air quality modeling? This is also known as dispersion modelling and simulations in some regions.

Air Quality Modeling

Modelers calculate what happens to pollution once it enters the surrounding atmosphere. Where it goes, how diluted it becomes in the process, and under what conditions it becomes a problem.

What is the point? To help ensure the facility is in compliance with the relevant air quality standards and objectives, which are designed to protect the environment.

These simulations use parameterized emission characteristics and the qualities of flow obstructions combined with background pollutant levels, local meteorological and topographic data.

The calculations result in predicted concentrations, which we compare with the standards to determine whether or not regulatory compliance has theoretically been achieved.

Example of an Environmental Group Working on air assessments.

How to conduct a typical project. What are the fundamentals of stack gas dispersion? What we do in this business amounts to:

  1. Creating a simplified design of the plant. Often the site plot plan makes a good starting place.

  2. Plant Sketch

  3. Taking this design, parameterizing and describing the details with an array of important numbers, such as building dimensions, stack heights and locations. We also need the stack diameter, exit temperature and velocity for a basic air dispersion model run. Air quality modeling predicts the downwind concentrations of the substances released by these sources.

  4. Deciding, sometimes with the guidance of regulatory personnel or government websites, which approved models to use. Modelling helps us distinguish anthropogenic effects on the environment from natural causes of air pollution, such as volcanoes, and background sources. Human sources include toxic air pollutants attributable to the plant, traffic, cities and photochemical smog to name a few.

    The most common models have names like ISC-prime, AERMOD, CALPUFF, RTDM and SCREEN3. They incorporate meteorological data, past weather observations, into the modelling to predict the likely transport and dispersion of fumes and plumes. We then use the output to answer this question: How does air pollution affect the environment?

  5. Examining the output from the air quality modeling. Using computer graphic software to compare the projected consequences with government department regulations. This often has us consulting more maps and pollution graphs. Graphical representations of model output can range from simple plots like this one,
    Air quality modeling stack

  6. to sophisticated animations from CALPUFF and other models.
  7. Offering solutions and alternatives to clients when a problem arises. In a nutshell, change the design of the plant and temperature of the hazardous wastes and check the outcome.

    You may need additional research, and air quality modeling professionals often liaise again with with design engineers at this point. The solutions modellers may come up with include:

    • building a taller stack
    • installing scrubbers and extraction system ventilation options
    • varying the mixture in the stack
    • erecting stacks and buildings in different locations
    • re-test by starting the air quality modeling again.

  8. Attending hearings to testify as expert witnesses on behalf of the client. These consultants assure the public citizen watch eco groups and officials that their concerns are properly addressed and situations with potential environment problems are improved. That's what we do.


If this is a process that your plant may have to go through, please let me know about your situation. Find out how to handle it. These air quality modeling projects are rarely trivial.

Environmental Problems

  1. The environment human interactions addressed by this kind of research could cover issues including: lung cancer, asthma, emphysema, allergies, smog, smoke and smoking, visibility and aesthetics, pictures, global warming and ozone depletion. On a federal scale, we also complete emissions statistics for the National Pollutant Release Inventory - NPRI - and Greenhouse Gas - GHG inventories in Canada.
  2. Regional and ambient contamination may come from substances such as sulfur, sulphur dioxide SO₂, carbon monoxide CO and dioxide CO₂, oxides of nitrogen NO₀ and NO₂, sulphuric or sulfuric acid H₂SO₄, mercury Hg, volatile organic compounds VOC's, benzene, toluene, chicken manure and fertilizer, which contain ammonia NH₃ amongst other air pollutants, dust and hydrogen sulphide H₂S to name a few. We have added fugitive leak detection and repair - LDAR - services to save clients money at the same time as preserving air quality.
  3. Exhaust, dust and waste comes from cars, trucks, planes, vans, and disasters such as fires and oil spills.

Have specialized needs? Call Barry Lough at 403-547-7557 (office).

Highlights from My Resume

For a detailed, Myers Briggs assisted, description of my personal preferences, see this page.


EDUCATION Undergraduate Science Diploma in Meteorology, University of Alberta, 1994
B.Sc., with specialization in Physics, University of Alberta, 1989

SUMMARY Barry has over 20 years experience in meteorology and dispersion modelling for permitting of upstream and mid-stream energy projects and industrial complexes.

He has worked as an atmospheric scientist, specializing in air quality modeling and operational meteorology. Additionally, Barry has experience with public liaison, mitigation and solutions for clients operating in environmentally sensitive regions.

Barry has considerable experience compiling emissions inventories, interpreting atmospheric influences, designing air monitoring programs and performing air quality modelling assessments. He has also developed programs and analytical techniques for evaluating the importance of air quality issues. Barry has contributed to problem solving in industry and government, specializing in air quality modelling, data validation and operational meteorology.

In past projects, Barry has been responsible for preparing air quality compliance information for industry license applications. Projects include compilation of complex emissions inventories and air dispersion modelling data, providing recommendations for modifications to plant design to meet air quality guidelines, assessing culpability in issues resolution and determining statistical calculation methodologies. Recent projects include:

  • Air quality dispersion modelling, using various U.S. EPA dispersion models for hundreds of oil and gas facilities. He has more recently become one of the Calvin Consulting (CCGL) experts in CALPUFF modeling.
  • Recommending alternate plant and stack design, based on predicted and actual ambient air quality effects.
  • Refining dispersion modelling techniques to accommodate changes in regulations, plant parameters, client needs and weather information.
  • Completing renewal and amendment regulatory approval applications for industry.
  • Determining optimal locations of air quality monitoring stations based on model output.
  • Preparing monthly and annual air quality regulatory reports

    Professional Affiliations & Registrations
  • Canadian Air & Waste Management Association Fields of Competence
  • Air quality dispersion modelling
  • License applications
  • Emissions inventories and reports
  • Interpreting meteorological data and weather forecasting

  • English, native speaker

    Key Industry Sectors
  • Oil & gas
  • Manufacturing
  • Petrochemical
  • Municipal power plants

Key Project Experience

Plant Design and Emission Sources Database, Licence Applications: Joffre Alberta Industrial Complex. This complex contains a chemical plant, a cogeneration facility, an Oligomers plant and a nitrogen fertilizer plant.

The projects required determining locations, emission parameters and building wake effects on several dozen streams operating simultaneously at these plants and using approved dispersion models to assess their effects on the surrounding terrain. Several consultations with operational personnel at all three sites were needed to arrive at final numerical data and provide accurate and complete air quality modeling. Design information, modelling results and interpretations were then reported to each client for inclusion in their respective license applications.

Specific modeling and data validation tasks for projects

Obtained and examined empirical ozone data, studied the physical principles and monitoring conditions, determined which values were realistic and kept them in a final data set to be used for further research and policy making.

Modelled and presented data for oil and gas facilities. Studied wide scale impacts of very large sources of carbon based emissions, NOX (oxides of Nitrogen) and particulate matter (PM). Extensive air quality modeling areas often contained other similar industries.

Designed simulations for modelling the dispersion of a wide variety of contaminants for natural gas derivative chemicals producers. Then air quality modeling for the dispersion of NOX using Ozone limiting techniques, carbon monoxide, ethylene and its effects on agriculture, benzene, butadiene, methyl pentane, PM and other substances including volatile organic compounds from two very large multi-facilities, close enough to each other to require a collective inventory of emissions. Made many small refinements to plant design, sometimes due to air quality modeling output and implications, resulting in incremental improvements to simulation within model scenario.

Created extensive modelling system for large natural gas pipeline projects. Worked with NOX and PM, often in the vicinity of other industrial or urban development, thus cumulative effects were inventoried and assimilated.

Parameterized emissions from “tepee” burners, and other source types and mitigations such as bag filters from an Oriented Strand Board (OSB) manufacturing facility.

Conducted fog predictions using customized air quality modeling program developed within one consulting company. This situation is frequently encountered in the vicinity of power plants and co-gen facilities which generate significant amounts of water vapour. Plants were located in Alberta and Saskatchewan. Fog is known for creating potentially hazardous driving conditions on nearby expressways, and a special air quality modeling program for predicting intensity and frequency of events was used for these projects.

Other Functions within air quality modeling projects:

Analyzed and interpreted air quality modeling output. Performed systematic calculations on the output data using processing software written for SAS applications. An example would be a custom program to make Ozone-limiting calculations for converting NO₀ concentrations to NO2 prior to the introduction of the ISC-OLM algorithms.

Plotted model output into a graphical form easily interpreted by scientists within group, using SAS applications or SURFER. Prepared contours of equal maximum concentration, known as isopleths and placed them onto maps of background area with matching scale and correct orientation, so that observers could easily determine the potential effects of source(s) on nearby areas of concern, such as residential developments.

Determined area to be selected for air quality modeling and data mapping, then created base map of the area using AutoCAD software. Map included extensive details to indicate terrain contours and other features. Cross hatching of varying densities made a visually appealing depiction of relief, making it easy to obtain a sense of the terrain shape after a short inspection.

When an air quality modeling output problem arose, such as the client's proposed situation resulting in unacceptable ambient concentrations, modifications were suggested to the design of the plant. Changes were made sometimes in an iterative fashion to arrive at an optimum solution, achieving satisfactory results at a minimum cost to the client. An example of this would be adding a quantity of extra fuel gas to a flare stack output flow, resulting in higher buoyancy flux, greater dispersion and lower concentrations before reaching the ground. Other solutions could include altering source and building placement, increasing stack heights, or adding an incinerator or filters to reduce the amount of harmful emissions in the flow as in the first place.

Prepared reports, made support calculations for testimonials at public hearings, kept in constant touch with chief consultant and quickly generated new model runs on demand, relaying the results to be used in justifying the client's proposed situation during its “day in court”.

Developed and documented efficient procedures for processing output and displaying graphics for the air quality modeling division of the consulting company's efforts towards achieving ISO9001 certification.

At Environment Canada, Meteorological Services of Canada. Formerly known as Atmospheric Environment Services.
Explained the occurrence of meteorological phenomena, using knowledge of atmospheric physical and dynamic systems while recognizing the strengths and limitations of model output. Created short-term predictions, keeping the clients' purposes in mind. Encoded forecasted into user-specified formats and publicly presented weather and climate information using computer and hand-drawn graphics.

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