Air monitoring
Odours, whether pleasant or foul, represent a significant challenge, here ASTM International propose a new practice for Environmental Odor Assessment (WK72782).
In the early 2000s, an unusual phenomenon gripped New York City.
Residents began reporting a persistent, sweet aroma drifting through the streets.
Not the typical urban scent of exhaust or waste, but the distinct smell of maple syrup.
It took years of investigation before researchers traced the source across the Hudson River to New Jersey.
Here factories were processing fenugreek seeds for food and fragrance additives.
Reflecting on the conclusion of the investigation in 2009, then-Mayor Michael Bloomberg stated: “Given the evidence, I think it’s safe to say that the ‘Great Maple Syrup Mystery’ has finally been solved.”
While the “maple syrup mystery” provided a rare moment of levity in urban monitoring, environmental odours are frequently far more contentious and potentially hazardous.
In the industrial sector, odours, whether pleasant or foul, represent a significant challenge.
They can disrupt local communities and lead to a surge in regulatory complaints.
They can even impact the operational welfare of employees.
A critical issue for environmental professionals is the public perception of risk; there is an inherent bias that suggests if an environment smells unpleasant, it must be toxic.
Although the New York syrup scent was eventually deemed harmless, the initial anxiety it caused highlights the need for a scientific method of assessment that moves beyond subjective experience.
To address these complexities, ASTM International’s committee on air quality (D22) has proposed a new practice for Environmental Odor Assessment (WK72782).
This standard represents a strategic shift toward an analytical, odourant-prioritisation-based approach.
It provides a technical foundation for problems that have historically been addressed with inconsistent or crisis-driven methodologies.
In announcing the new standard, committee member Jacek Koziel emphasised the practical origins of the framework:
“The approach in the proposed standard has emerged for its developers from 30 years of practical application to real-world industrial and consumer odour-quality problem-solving.
“The diversity of targeted odourous environments has ranged from agricultural to industrial to consumer products.”
For decades, odour analysis was often treated as a secondary concern or a scientific curiosity rather than a rigorous discipline.
This lack of standardisation meant that industrial investigations were frequently reactive.
The core of the proposed standard is the use of structured analytical techniques, such as multidimensional gas chromatography.
This helps to isolate the specific compounds responsible for a scent profile.
By focusing on these “character-defining compounds,” researchers can bypass the vast chemical background noise to find a solution more efficiently.
“When you’re dealing with odour problems in industry, if you’ve got a product that has a malodour and you’re in the business of selling that product, you really don’t have a choice – you’ve got to solve that problem,” says committee member Don Wright, an expert in multidimensional gas chromatography.
“We found that if we can trace an odour character-defining compound back to its source, the roadway and distance to a solution can be much shorter.”
One of the methodology’s primary strengths is its ability to simplify the analytical target.
Instead of attempting to catalogue every chemical present in a complex industrial emission, the standard directs investigators to identify the primary drivers of the odour.
As the committee notes: “It’s not necessary to define the extremely complex background that accompanies these critical players.
“What we need to do is find if there’s a character-defining compound that’s hidden in that complex emission from that source that is primarily responsible for the problem.
“We’ve learned to not look at the noise that accompanies these critical compounds.”
WK72782 is intended to serve as a diagnostic screening tool.
It does not aim to replace existing standards that utilise human sensory panels.
These remain essential for determining regulatory “acceptability”.
Instead it should provide a chemical blueprint for mitigation.
By identifying the “low-hanging fruit” of odour chemistry, the standard allows firms to develop more targeted monitoring and engineering strategies.
“The general impression in the environmental odour arena is that odour is inherently complex, and it is if you look at all of the noise you collect in these environments,” Wright explains.
“But, as it turns out, that’s really not the case.
“In most cases, impactful odours can be relatively simple.
It might only be a few compounds, or even a single character-defining compound causing the odour.
“That’s what this method specifically looks for: screening for low-hanging fruit.
“Let’s make sure there’s not a simple answer before we start generating much more data.”
As regulatory pressure and community expectations regarding air quality continue to rise, the move toward an analytical, compound-specific assessment of environmental odours offers the industry a more precise roadmap for compliance and stewardship.
Adapted from the article originally published in ASTM International, with permission from Standardization News.
Lab Asia 33.2 April
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