Odor Control and Odor Thresholds

Related Resources: civil engineering

Odor Control and Odor Thresholds

Odor Control and Odor Thresholds for Human Smell

Ventilation engineering:

(1) contemporary construction methods result in buildings that allow less air infiltration through the building envelope;
(2) indoor sources of odors associated with modern building materials, furnishings, and office equipment have increased;
(3) outdoor air is often polluted; and
(4) energy costs encourage lower ventilation rates at a time when requirements for a relatively odor-free environment are greater than ever.

Outdoor odor sources that may require engineering mitigation are:

automotive exhaust
diesel exhaust
hazardous waste sites
sewage treatment plants
compost piles
refuse facilities
printing plants
refineries
chemical plants

indoor odor sources include

tobacco products
bathrooms and toilets
building materials
- (e.g., adhesives,
- paints,
- caulks,
- processed wood,
- carpets,
- plastic sheeting,
- insulation board),
consumer products (e.g., food, toiletries, cleaning materials, polishes),
hobby materials,
fabrics,
foam cushions.
offset printing processes,
copiers,
computer printers
Electrostatic processes may emit ozone.
Humans emit a wide range of odorant's
- acetaldehyde,
- ammonia,
- ethanol,
  hydrogen sulfide,
- mercaptans.
Mildew and other decay processes often produce odors in occupied
spaces (home and office),
damp basements,
ventilation systems (e.g., from wetted air-conditioning coils and spray dehumidifiers).

The table below shows odor detection threshold concentrations for selected compounds. The threshold limit value (TLV) is the concentration of a compound that should have no adverse health consequences if a worker is regularly exposed for 8 h periods (ACGIH, revised annually). For ratios greater than 1, most occupants can detect the odor and leave the area long before the compound becomes a health risk. As the ratio increases, the safety factor provided by the odor also increases.

Compound	Odor Threshold,^a ppmv	TLV,^b ppmv	Ratio
Acetaldehyde	0.067	25-C	360
Acetone	62	500	8.1
Acetonitrile	1600	20	0.013
Acrolein	1.8	0.1-C	0.06
Ammonia	17	25	1.5
Benzene	61	0.5	0.01
Benzyl chloride	0.041	1	24
Carbon tetrachloride	250	5	0.02
Chlorine	0.08	0.5	6
Chloroform	192	10	0.05
Dioxane	12	20	1.7
Ethylene dichloride	26	10	0.4
Hydrogen sulfide	0.0094	10	1064
Methanol	160	200	1.25
Methylene chloride	160	50	0.3
Methyl ethyl ketone	16	200	12.5
Phenol	0.06	5	83
Sulfur dioxide	2.7	2	0.74
Tetrachloroethane	7.3	1	0.14
Tetrachloroethylene	47	25	0.5
Toluene	1.6	20	13
Trichloroethylene	82	10	0.1
Xylene (isomers)	20	100	5

Sources: ACGIH (updated annually), AIHA (1989).

^aAll thresholds are detection thresholds (ED50).
^bAll TLVs are 8 h time-weighted averages, except those shown with -C, which are 15 min ceiling values.

Source

ASHRAE Handbook, I-P Eidtion 2021