Permitting and impact assessment
New facilities, modifications, permit renewals, environmental-impact studies, separation distances, and comparison with applicable odor criteria.
Odor assessment · dispersion modeling
Turn odor concerns into evidence and practical action.
We characterize sources, model short-term odor exposure, investigate complaints, compare mitigation options, and prepare clear technical evidence for permitting, design, operations, and community-impact decisions.
Sources, odor emission rates, meteorology, terrain, buildings, sensitive receptors, peak concentrations, frequency, and duration.
Complete assessment chainfrom emissions to receptors and mitigation
Short-term expertisemethods suited to how odor is perceived
Field and modeling evidencemultiple lines of evidence where appropriate
International perspectivemethod adapted to local criteria and guidance
What we provide
More than an odor contour map.
Odor nuisance is shaped by the source, the atmosphere, the character of the odor, and the people and land uses exposed. We connect these elements in a proportionate, reviewable assessment.
Source and emission characterization
Point, area, volume, open-tank, building, fugitive, intermittent, and time-varying sources, with measured or estimated odor emission rates.
Field surveys and complaint analysis
Field inspection planning, trained-panel surveys, georeferenced observations, complaint review, and correlation with operations and meteorology.
Dispersion and exposure modeling
Spatial and temporal odor concentrations, short-term peaks, percentiles, threshold exceedances, episode duration, sensitive receptors, and cumulative impact.
Mitigation and design evaluation
Compare capture and treatment, enclosure, stack design, operating schedules, process changes, source relocation, and alternative site layouts.
Forecasting and operational support
Weather-aware planning and automated forecasts can help schedule sensitive activities, anticipate risk, and support responsive site management.
FIDOL framework
Concentration alone does not describe nuisance.
We interpret results through the factors that shape human response. Their importance depends on the project, the odor, the assessment criteria, and the sensitivity of nearby land uses.
- FFrequency
How often people are exposed and how frequently the selected odor threshold is exceeded. - IIntensity
The perceived strength of the odor, informed by concentration, short-term fluctuation, and the odor-specific response. - DDuration
How long individual odor episodes persist and whether exceedances are isolated or consecutive. - OOffensiveness
The odor character and hedonic tone: an odor’s nature can strongly influence the response at a given intensity. - LLocation
The sensitivity of the affected setting, including homes, schools, hospitals, workplaces, hospitality, and recreation.
Assessment method
A traceable path from concern to control.
Define the decision
Establish the project scenarios, applicable criteria, receptors, averaging periods, percentiles, and questions the study must answer.
Understand the setting
Review land use, sensitive receptors, terrain, buildings, background sources, complaints, operating records, and existing evidence.
Build the odor inventory
Identify each source and its geometry, flow, concentration, temperature, timing, variability, controls, and uncertainty.
Prepare meteorology
Select representative observations or simulations and examine calm winds, stability, drainage, coastal effects, and complaint conditions.
Select and configure the model
Match the model and peak treatment to the source, terrain, time scale, jurisdiction, available data, and required assessment statistics.
Quality-check and test
Review mass flow, units, coordinates, source behavior, model options, receptor coverage, and influential assumptions.
Interpret exposure
Map concentrations and evaluate percentiles, frequency, duration, source contributions, sensitive receptors, and uncertainty.
Compare mitigation
Quantify the reduction needed, test practical controls and operating scenarios, and identify measures that address the controlling sources.
Report for action
Prepare a transparent technical record with assumptions, results, limitations, maps, recommendations, and review support.
Model selection
Odor needs the right treatment of time.
People perceive odor over seconds or minutes, while many dispersion models produce hourly averages. We select a defensible short-term method rather than treating odor like a conventional annual-average pollutant.
- 01LAPMOD
Our three-dimensional Lagrangian particle model can calculate short averaging periods directly and postprocess frequency, intensity, duration, and location indicators. - 02AERMOD
Used where appropriate for regulatory-style near-field assessments, with a documented approach for converting hourly predictions to short-term odor peaks. - 03CALMET / CALPUFF
Considered for non-steady meteorology, complex terrain, coastal settings, calm conditions, and other cases suited to a puff-model framework. - 04Peak-to-mean treatment
Where the model produces hourly means, an appropriate peak-to-mean relationship is selected and documented for the source, distance, turbulence, and applicable guidance. - 05Regulatory alignment
Odor criteria and accepted methods vary substantially by jurisdiction. The final approach follows the competent authority’s requirements and project context.
Applications
Different sources require different evidence.
We adapt source representation, temporal profiles, sampling strategy, meteorology, receptors, and mitigation testing to the actual process and site.
Waste, composting, and biogas
Receiving areas, storage, handling, active treatment, maturation, leachate, landfill surfaces, gas systems, doors, vents, and episodic operations.
Industry, food, and materials
Process vents, tanks, wastewater, chemical and petroleum operations, food production, rendering, pulp and paper, asphalt, and other industrial sources.
Guidance and independent review
Scope development, method review, sensitivity analysis, third-party study audits, and support informed by international odor-modeling practice and published research.
Forecasting and communication
PrOlor combines automated modeling with simple receptor-based communication to support daily operations and proactive odor management.
Tools and knowledge
Useful resources before and beyond a full study.
Background material and simplified screening tools. These are useful for early checks; complex sites still require a project-specific assessment.
01Stack height
Screen the stack height needed to meet a selected ground-level odor criterion, with simplified checks for rising terrain or a nearby building.
05Stack-tip downwash
Estimate reduced effective stack height when exit velocity is low.
06Odor fundamentals
Explore FIDOL, intensity, detectability, character, and hedonic tone.
Plan odor control before decisions become expensive.
We can define the assessment, test layouts and controls, compare operating scenarios, and prepare the technical evidence needed for permitting and design.
Discuss the assessment →Investigate complaints and identify practical responses.
We combine source review, operational data, meteorology, field evidence, and modeling to clarify likely causes and prioritize effective mitigation.
Plan an investigation →Important: odor thresholds, percentiles, averaging times, peak-to-mean methods, and accepted models vary by jurisdiction. Simplified tools are suitable only for screening; site-specific permitting and complex terrain or building cases require a documented assessment agreed with the competent authority.
Start with the decision you need to make
Bring us the site, sources, receptors, and odor concern.
We will help define the measurements, meteorology, model, scenarios, criteria, and mitigation testing needed for a proportionate and defensible study.