Frequency
How often people are exposed to an odor, or how often a selected odor threshold is exceeded. Frequent exposure can make even a mildly pleasant odor unacceptable.
Odor assessment · FIDOS framework
FIDOS assessment factors
Odor nuisance is not described by concentration alone. The FIDOS framework combines how often an odor occurs, how strong it is, how long it lasts, how unpleasant it is, and where people experience it.
Odor impact depends on source behavior, atmospheric dispersion, odor character, receptors, and land use.
Human responseassessment linked to perception and nuisance
Short-term exposurefrequency, peaks, and episode duration matter
Odor characterhedonic tone changes acceptability
Receptor sensitivityland use affects the level of concern
The five factors
What FIDOS means in practice.
The framework is a screening and interpretation aid for proposed or existing developments. It helps connect model results, field evidence, complaints, and site context.
Intensity
The perceived strength of the odor. It is related to odor concentration, short-term fluctuations, and the response of people to that specific odor.
Duration
The length of individual odor episodes, including how long concentrations remain above the odor threshold and whether episodes occur consecutively.
Offensiveness
The combined effect of odor character and hedonic tone. Some odors are broadly considered offensive, while others become unacceptable mainly when exposure is unwanted or persistent.
Sensitivity
The sensitivity of the affected setting, including homes, schools, hospitals, offices, restaurants, shops, and outdoor recreational areas.
Assessment context
FIDOS factors are interpreted together with local criteria, source uncertainty, operating scenarios, meteorology, terrain, buildings, and receptor distribution.
How it supports studies
FIDOS turns odor results into decision-ready evidence.
An odor model may predict concentrations, percentiles, and threshold exceedances. FIDOS helps interpret those outputs in terms of likely nuisance, sensitive locations, and practical mitigation priorities.
- 01Frame the question
Define receptors, odor thresholds, operating scenarios, assessment statistics, and the decisions the study must support. - 02Quantify exposure
Estimate peak odor concentrations, exceedance frequency, episode duration, and spatial patterns with a suitable dispersion model. - 03Interpret nuisance potential
Combine model outputs with odor offensiveness, receptor sensitivity, field observations, complaints, and uncertainty. - 04Prioritize mitigation
Use the dominant FIDOS drivers to compare source controls, operating changes, stack design, enclosure, treatment, or forecasting actions.
Related Enviroware resources
From screening to full odor assessment.
FIDOS is one part of a wider odor-assessment workflow that may include field inspection, source characterization, emission measurements, meteorological analysis, dispersion modeling, and mitigation testing.