AN OVERVIEW OF ODOUR TESTING
The business of ‘smelling’ is undoubtedly unusual. So at Silsoe Odours we get lots of questions about what’s involved. Are you curious about the process of odour testing, and how odour assessors fit within it? Or, as we affectionately know them – sniffers! They are blessed with a very specific sense of smell, together with a willingness to put their nose where nobody else dares to. Here’s what else you need to know about odour testing and how the process works…
A REPRESENTATIVE SAMPLE OF THE POPULATION
Can you sniff out a jam doughnut at 100 paces? Or maybe you’re oblivious to the delights of the perfume department at duty free? If that sounds like you, then you won’t cut it as a sniffer at Silsoe Odours! We conduct olfactometry analysis at our laboratory in Bedfordshire, which gives results consistent with the population’s average sensitivity to smell. In other words, our odour panel forms a representative group of the population. We have a stringent selection process (supported by ongoing testing) to make sure our odour assessors fit within a specific range of odour sensitivity.
THE ROLE OF THE SNIFFER
Primarily, our odour panel is responsible for analysing an odour once it has been collected from a site.
Our UKAS accredited sampling team usually collect the samples by way of an odour sampling survey. However, many clients also send us samples they’ve collected themselves, using our ‘lab only’ service.
Generally speaking, the most popular odour testing service we offer is odour concentration testing. But our clever bunch of sniffers also test samples for other features and characteristics. This includes odour characterisation (what it smells like), intensity (how strong it is) and hedonic tone (how pleasant it is).
OBJECTIVE ODOUR TESTING
Only 1 in 3 applicants for a Silsoe Odours sniffer role are successful. We look for the most objective, consistent data output possible. The laboratory team select odour assessors using a process of testing in line with the European Standard BS EN13725. Our odour testing laboratory is also UKAS accredited. So you can rest easy at the quality of our results.
Furthermore, our sniffers work in teams of six to ensure the highest possible level of objectivity.
A TRUSTWORTHY NOSE
Repeatability is key in our lab! It’s the most crucial element for our odour assessors, as a changeable nose makes odour testing results inconsistent. With this in mind, we put our sniffers through their paces on a regular basis. In this way, we make sure their sniffing senses continue to be consistent. There’s a lot to be said for a trustworthy nose!
HOW DOES ODOUR TESTING WORK?
To measure the concentration of an odour, we present a panel of six sniffers with two samples. The first is a dilution of the odour sample, the second a sample of clean air.
We use sniffing ‘horns’ connected to an olfactometer (a specialist laboratory instrument) to do this. The panel then selects which horn contains the odour, through a ‘forced-choice’ assessment. They must specify whether their answer is a guess, inkling or certain choice.
We repeat the process with increasingly higher concentrations of odour. We’ll only stop when all six assessors are certain the odour is present on two successive occasions. The final output gives each sniffer an individual threshold estimate. Finally, we calculate the results to give us the geometric mean of the odour concentration in the sample.
WHAT’S THE STINK?
You’re probably wondering what kind of thing we come across when odour testing. Well, the most common odour our sniffers encounter is from sewage works. But they could also be faced with anything from to leather to rotten eggs to pet food. Ordinarily it’s really not as bad as it sounds though!
COMMITTED TO THE ODOUR TESTING CAUSE
The odour laboratory at Silsoe Odours is far from your average workplace. In fact, it’s completely odour free! And that’s trickier to achieve than you might think. We task all our odour assessors with very strict requirements. For instance, they must not use fabric softeners or conditioners on their clothes, or wear perfume or aftershave.
But don’t worry, we keep things fresh with our trusty air conditioning system. Sniffers also leave their teas and coffees outside, and avoid stinky foods before coming in. We even banished glossy magazines, as there’s a scent in the ink that can impact the odour testing results.
ODOUR SENSITIVITY TESTING
Fancy having a go yourself? If so, take a look at our odour sensitivity testing service. It’s a handy way to compare your personal odour sensitivity with the population average. Or in the case of odour complaints, with the complainant’s odour sensitivity. You’ll find it useful if you’re involved in monitoring odours, whether that’s at a plant, for planning purposes or from a regulator perspective.
It also gives you a great excuse to check out our UKAS-accredited odour laboratory. And don’t worry, we won’t subject you to anything too stinky. We keep it strictly to n-Butanol. All tests are compliant with European Standard BS EN13725.
Institute of Air Quality Management (IAQM)
Guidance on the assessment of odour for planning
Odour Study Day
To learn more about odour testing, with a comprehensive overview of odour management, take a look at the Odour Study Day. The course is CPD certified, accredited by CIWEM and endorsed by the IAQM. It gives you a taster session in the Silsoe Odours laboratory.
Updated from ‘Odour Testing – The Importance of Odour Assessors’ blog, dated March 2018.