Unpleasant Odors: A Problem Beyond the Nose
23/05/2025
Olfactometric Analysis: History, Methods, and Tools for Odour Management
A Historical Anecdote
Several years ago, the founder of the group of companies to which Paneco Ambiente belongs shared a personal anecdote related to the world of odours.
Early in the morning, drawn by the scent of freshly baked bread, he entered a bakery that had an adjoining sales area. The smell was so pervasive that he said, “It felt like being inside a loaf of bread.”
The aroma had impregnated everything—from the oven to the walls—with such intensity that it almost seemed tangible.
Observing the walls, he had the intuition to sample the thin organic film that must have formed over time on the surfaces.
His intuition was confirmed: chemical analysis revealed that this thin layer contained volatile compounds characteristic of bread.
Introduction
Smells are an integral part of the air we breathe and our daily interaction with the environment, from the aromas of cooking and food products to the odorous emissions of industry. Everything related to the world of odours and scents, whether unpleasant or pleasant, affects our mood and, in general, our quality of life as citizens. Consequently, olfactory monitoring is of crucial importance: it allows us to protect air quality, comply with increasingly stringent national and EU regulations, and optimise emissions from production processes that would otherwise remain too discretionary. Olfactometric analyses were created precisely to bring objectivity to a notoriously subjective sense: they are based on standardised protocols and can integrate the acuity of the human nose with the sensitivity of advanced instruments.
In this article, we will explore the historical evolution of the discipline, the regulatory context in Europe and Italy, the physiological basis of olfactory perception, official and instrumental methodologies, sampling protocols, data analysis and practical applications.
Historical Background of Olfactometric Analysis
Olfactometric analysis is a scientific discipline that quantifies odour perception through specialised instruments and standardised procedures.
Even in ancient times, philosophers such as Aristotle and Galen linked smells to states of health and natural processes: in their model, “miasmas” were responsible for diseases, and analysing them meant attempting to prevent epidemics. However, until the 18th–19th centuries, the method remained predominantly empirical and linked to qualitative descriptions.
The real breakthrough came with Dutch physiologist Martinus Zwaardemaker, who at the end of the 19th century created one of the first “olfactometers”: simple chambers in which odorous air was diluted with pure air to understand at what concentration a given stimulus became perceptible. This approach paved the way for the first attempts to systematise volatile molecules according to their aromatic profile, anticipating chemical separation techniques by decades.
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During the 20th century, especially since the 1970s, dynamic dilution methods became widespread: thanks to flow meter systems and valve matrices, it became possible to precisely mix “dirty” air and “clean” air. Dynamic olfactometry, now standardised in EN 13725, made it possible to define the human “perception threshold” in a reproducible manner, expressed in odour units (ou/m³).
At the same time, technology drove the integration of human sensory analysis and chemical instrumentation: gas chromatography-olfactometry (GC-O) and the first electronic noses appeared in the 1990s, making it possible to associate a chromatographic peak with the sensory experience of a sniffing panel. Since then, the discipline has continued to evolve, becoming today a combination of environmental sciences, sensory biology and sensor engineering.
The Regulatory Framework in Europe and Italy
In the European context, EN 13725:2003 is the reference standard for olfactometric analysis.
This standard defines how to:
Collect air samples containing odorous substances
Analyse them using trained panels of assessors
Determine the odour concentration in ouE/m³
In Italy, odour management is governed by both national and regional regulations.
In 2012, the Italian Ministry of the Environment published the Guidelines for the Management of Odorous Emissions, providing operational tools for companies and control authorities.
Additionally, several Italian regions have developed specific regulations for monitoring and controlling odours, especially in sectors such as:
- Waste Management
- Legislative Decree 183/2017 of 15 November 2017, which updates the T.U.A. (Consolidated Environmental Act) by introducing Article 272-bis, specifically dedicated to the “measurement and management of odour emissions” and defining the requirements for laboratories and the obligation to transmit results to the control bodies.
- Ministerial Decree 28/06/2023 (Ministry of Ecological Transition), which operationally supplements standard EN 13725 with reference thresholds for industrial sites at greater risk of odour pollution and updates the calibration protocols for dynamic olfactometers.
The picture is completed by regional guidelines (Lombardy, Emilia-Romagna, Veneto, etc.), which detail operational protocols (monitoring distances, environmental conditions) and Integrated Environmental Authorisations (IEA), which often require periodic olfactometric analyses as a condition for maintaining authorisation. Finally, Italian case law has repeatedly affirmed the right of individuals exposed to odour nuisance to compensation for environmental damage.
How We Perceive Smells: The Human Nose
Odour perception begins in the olfactory epithelium, located in the upper nasal cavity.
Here, receptors detect volatile molecules and transmit signals to the olfactory bulb, which interprets them and generates the perception of smell.
Individual perception varies according to:
- Personal sensitivity
- Intensity
- Cultural and psychological factors
This inherent subjectivity is what makes olfactometric analyses so valuable: they standardise odour evaluation by using trained panels or specialised instruments
Official Methods
Dynamic Olfactometry
Defined by EN 13725, this method involves diluting an air sample and presenting it to a trained panel via an olfactometer. Assessors indicate the moment they first detect the odour, allowing calculation of the detection threshold and concentration. It is quantitative and the most widely recognised for regulatory compliance.
Field Inspection (Grid Method)
Teams of assessors survey a designated area, recording odour intensity and frequency at fixed points. Useful for mapping dispersion in open environments.
Gas Chromatography (GC)
separates and identifies chemical components in odorous mixtures.
Electronic Nose (E-nose)
mimics human olfaction with sensor arrays and software. While less precise than the human nose, it enables continuous monitoring and quality control.
- Continuous monitoring in purification or composting plants.
- Quick verification in food or cosmetic production.
However, they require frequent calibration to compensate for sensor drift and generally maintain a sensitivity lower than that of humans for substances at very low concentrations.
Sampling Techniques and Protocols
Reliable results depend on strict sampling procedures. Key considerations include:
Sampling point selection: representative of the source
Equipment: inert materials (e.g., Nalophan bags) to avoid contamination
Storage time: samples should typically be analysed within 30 hours
Environmental conditions: temperature, humidity, and wind affect dispersion and perception
Samples are then analysed following calibration protocols, assessor training, and standardised data interpretation.
Data Analysis and Odour Mapping
Olfactometric data enables:
- Determination of odour concentration (ou/m³)
- Mapping of emission distribution
- Monitoring over time
- Predictive modelling using software such as CALPUFF or AERMOD
These simulations account for wind, terrain, and source characteristics, supporting environmental impact assessments and permitting processes.
Applications
Olfactometric analyses are applied in a wide range of sectors, including:
- Waste treatment & composting: identifying and reducing nuisance odours
- Wastewater treatment: monitoring aeration and sludge drying emissions
- Food & beverage industry: flavour profiling (cheese, wine, coffee) with GC-O
- Cosmetics & perfumery: testing fragrance stability, shelf life, and consumer acceptance
Environmental management: ensuring compliance in landfills, biogas plants, and composting facilities
Industrial processes: petrochemicals, plastics, paints, varnishes, pharmaceuticals, paper, tanning, pet food, foundries, and more
The Paneco Ambiente Approach
At Paneco Ambiente, we combine scientific rigour, practical experience, and tailored solutions. .
Our team conducts olfactometric analyses in accordance with national and European standards, applying both official and instrumental methods.
We support companies in:
- Evaluating emissions
- Reducing environmental impact
- Managing odour-related complaints
Enhancing corporate image and social responsibility
In addition, we develop biotechnological solutions that target odours at their microbiological source, reducing emissions before they spread.
Conclusions
Olfactometric analyses are essential for modern environmental monitoring and odour management.
They bring objectivity to something once considered purely subjective, enabling effective regulation and mitigation.
In an increasingly regulated and socially conscious context, the ability to identify, measure, and manage odours represents both a responsibility and a competitive advantage.
The future of odour control lies in the integration of science, technology, and sustainable practices, a path Paneco Ambiente has pursued since its foundation.
