If you
ever had an odor issue within your facility,
you will know the difficultly in identification
of a source(s) and cause(s). The following
summary and recommendations have proven
to be successful in the identification
and mitigation of odor sources.
Chemical compounds from chemical products
or microbiological activity typically
cause odors. Odors can be perceived
with olfactory senses even when the
contaminant concentration cannot be
detected by sensitive analytical instrumentation.
Compounds that cause odors can oxidize
and change chemically making their detection
difficult and / or impossible.
The release of an intermittent odor
from an indoor cause and source is generally
regulated by a change in its pathway(s)
and driving force(s). Driving forces
determine the pathway from an odor source.
Building pressure, system pressures,
temporary or permanent blockages causing
pressure build-up, HVAC systems, and
the effects of weather conditions on
a building are examples of driving forces.
Odors are from sources:
- external to a building, i.e. not
related to a buildings systems,
or processes and occupants within
a building
- internal to a building, i.e. related
to a buildings systems, or processes
and occupants within a building
Outdoors
Outdoor entrainment can occur through:
- outdoor air intakes
- uncontrolled leakage due to negative
building pressure and / or system
pressure
Outdoor causes and sources can
be extensive, but general categories
include:
- Vehicle emissions
- Fugitive emissions from nearby
facility(s)
- Fugitive emissions from other
parts of facility
- Ground gases from soil contamination
Indoors
Indoor dispersion can occur via the
HVAC system(s), and other controlled
and uncontrolled airflow, which are
caused by many factors.
Indoor causes and sources include:
- Building systems
1. Sanitary sewage discharge and
venting systems
- Re-entrainment of vented gases
(methane / hydrogen sulfide),
this would tend to distribute
odors throughout all areas served
by an HVAC unit
- Breach in vent stack / vent
stack joints located within
the structure (methane / hydrogen
sulfide) intensity of odor would
depend on system use, size of
breach, draft within vent, pressure
differential between vent pipe
and surrounding area, back pressure
caused by discharge flow volume
variations and interception
point flow restriction,
- Broken seals around water
closets and urinals
- Dry or unsealed drain traps
- Broken discharge pipe resulting
in odor accumulation under the
slab. Intensity of the odor
would vary with building pressure
in relation to under slab pressure,
cracks in the concrete flooring,
floor penetrations for conduits
- Grease traps that are improperly
maintained
- Insufficient pitch of sanitary
sewage lines under the floor
2. HVAC systems
- Condensation pan and drain
- Wet insulation, in duct or
mix box
- Mold growth in the HVAC system
and associated ductwork
- Insufficient or excessive
exhaust air
- Entrainment of kitchen exhaust
air
- Fuel fired boilers
3. Electrical systems
- Overheating ballasts with
melted insulation
- New computers or other electronic
equipment
- Emergency generators
4. Roofing
- Breach in roof integrity which
would allow water liquid flow
and allow for the growth of
bacteria and mold in the roofing
system
- Odors from chemicals, tar,
and other products used during
roof replacement
5. Windows and walls
- Water intrusion around windows
resulting in hidden mold and
bacteria growth and decomposition
of materials
- Water absorption and transfer
through brick and mortar resulting
in hidden mold and bacteria
growth and decomposition of
materials
- Water intrusion around flashing
etc resulting in hidden mold
and bacteria growth and decomposition
of materials
6. Floor systems
- Cracks and floor penetrations
allowing soil gases to enter
the building. Intensity of the
odor would vary with building
pressure in relation to under
slab pressure, cracks in the
concrete flooring, and floor
penetrations for conduits. Subsurface
conditions and or pollution
can be a source.
- Floor penetrations between
floors that allows transfer
of odors from one floor to another
- Raise flooring allows for
collection of debris and rodents
- Cabling channels in floor
covered with steel plated. May
dead end at an odor source,
or receive and hold water
- Occupants
1. Personal hygiene product use
- Level of personal care
- Perfumes and colognes
2. Sabotages
- Intentional release or application
of an odor or irritant causing
substance
3. Food storage
- Food storage in closets, desk
drawers, and waste cans
- Processes
- Processing equipment
- Manufacturing equipment
- Maintenance procedures / chemicals
- Housekeeping
- Trash storage and disposal
systems
- Loading docks
- Furniture systems
- Off-gassing of new furniture
- Odors from stored or used
furniture
In order to assist in the resolution
of odor issues, it is beneficial to
gather some information first to assist
in determining what types of sampling
and where the sampling needs to be
conducted within the facility. Questions
such as the following need to be answered
prior to conducting any type of sampling
or assessment.
- When odor is present, what are
its boundaries?
- We know where the odor does not
appear?
- What is the pattern associated
with the odors presence?
- Is odor present above ceilings?
- What does the odor smell like?
- Does weather affect the presence
or intensity of the odor?
- Is odor present throughout an
entire areas served by an AHU?
- Is odor present before employee's
come into building?
- Are HVAC systems shutdown overnight?
- Are there any janitor closets
in the areas?
- Is odor present during the night?
Recommendations:
- Get answers to the above noted
questions
- Begin keeping a log for a few
weeks. This might allow us to look
back at what was occurring in the
building at that time.
- When odor is present shut down
systems and conduct air sampling
and olfactory evaluations to identify
areas of low and high intensity.
This will assist in focusing in
on the point source, as contaminants
tend to migrate in a rolling fashion
from a source.
- Evaluate air prior to employees
coming in to work.
- Conduct air sampling with various
direct reading and sampling media.
Need more information, or a proposal?
Please click on
Information Request, or contact
Chris Schneider, CIH, President at
888.873.9983, Ext 14 or
cschneider@1ssh.com
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