Building 42 Wrest Park Silsoe BEDFORD Bedfordshire MK45 4HP
01525 860222

Sniff Surveys

Odour surveyor in field


A sniff survey is an independent subjective survey that measures the impact of odours. Known by many names, you may also see it referred to as a sniff test, odour survey or field odour survey. It identifies the specific odour source, or sources, where it is not known.

At Silsoe Odours, we use the results of this type of odour survey to provide clients with scientific evidence relating to your odour emissions. Our report will enable you to measure, evaluate and ultimately control the odours which your plants and processes may produce.

Our sniff surveys are conducted by qualified odour panellists, in line with BSEN16842-2 guidelines. They determine the effects of odour dispersal over a determined period in a range of meteorological conditions.


We provide the results of the sniff survey in an easy-to-read report. The report contains details that help inform odour management plans and implement odour control measures. Many clients find this extremely useful for satisfying the regulator’s requirements, particularly following public complaints relating to malodours.

A sniff survey is helpful for:

– A field odour impact assessment without requiring access to the site
– Identifying odour sources where multiple sites are in close proximity
– Confirming the results of dispersion modelling
– Informing odour management plans
– Confirming the details of odour complaints


Sniff surveys use a series of observation points located downwind of the suspected source of the odour. Panellists keep detailed records to track intensity and frequency. The term ‘plume’ describes the trajectory of the odour and the dispersal pattern created as it meets atmospheric turbulence. We record data at regular intervals, noting meteorological divergences. Our human assessors use the ‘sniff test’ to determine the absence or presence of the odour, and its journey is plotted by noting where the smell is at its most intense and at what point it disappears.

The composition of the panel for any given odour survey will remain constant throughout the testing process, and the manner of assessment will determine the number of panellists:

Plume Method – a minimum of five assessors.
Dynamic Plume Method – a minimum of two assessors.

assessor wind flow chart


The simplified diagram in Fig. 1 illustrates the idealised progression of the assessors. The wind indicated by the arrow 1, the odour source is at 2. Black spots indicate where an odour is detected and circles where no odour is detected. The plume extent is drawn between odour present and no odour points. Panel members will make an assessment every 10 seconds.


We conduct sniff surveys using our qualified odour panellists, led by one of our highly experienced odour experts. All our panellists are selected and continually checked according to the requirements of BSEN13725.

During the survey, the odour panel will use a series of observation points located downwind of the suspected odour source, to track its intensity and frequency. We conduct these observations in line with Institute of Air Quality Management (IAQM) Guidance and/or European Standard BSEN16842-2.

We design all of our sniff surveys to respond to subjective experiences of odour impact, representative of the kind of complaints our clients may face from members of the public

Client testimonials

Don’t take our word for it – here’s what our clients say:

We were seeking planning permission for a development which is adjacent to a site with known odour issues. We had completed our own survey, but the council asked for an independent odour assessment. We approached Silsoe Odours as had previously had a good experience with them for olfactometry work, and knew they had prior knowledge of the site. I was particularly impressed with the way they presented and summarised their data. It was easy to understand and presented in such a way that the layman could understand. I wouldn’t hesitate to recommend Silsoe Odours and look forward to working with them again in the future.

Graham Harker

Peter Brett Associates

To find out more about sniff surveys, call our team on 01525 860222.