16 2011 ARC

Odor abatement for commercial andindustrial facilities _*.*Tom N. Petersen rironmental and Engineering Solutions, Inc.

Indoor air quality (IAQ) is a constantly changing in-teraction of biological, chemical, and physical f ac-tors. One sign of poor IAQ is the presence ofunpleasant odors. In a number of recently docu-mented cases, "sick building syndrome/' a termused to describe buildings with hazardous air conta-minants, has been cited as the primary culprit in theshutdown of workplaces for extensive cleanings andrenovations. Proper IAQ management, includingodor control, can prevent such shutdowns, and ulti-mately save companies millions. The methods usedfor odor investigations and odor abatement in com-mercial and industrial facilities are described in thisarticle.

Assessing building air quality and odors incommercial facilities

A commercial setting provides a limited set of odorcauses and concerns. The cause could be as simple asunremoved garbage or low-quality housekeepingpractices. However, odor problems can be morecomplicated. Unpleasant odors in a commercial fa-cility can be the result of a combination of factors, in-cluding the site, climate, building constructiontechniques, outdoor air quality, contaminant sourcesand their strengths, building occupants, and the de-sign, operation, and maintenance of heating, venti-lating, and air conditioning (HVAC) systems.Therefore, the odor investigation and abatementprocess requires patience and determination.

To shorten the cycle from an odor complaint to theresolution of the problem, it is very helpful to havegood documentation for the building. Buildingowners or operators should consider developing anIAQ Profile—a description of the features of thebuilding's structure, function, and occupancy thataffect air quality—to serve as an owner's manual orreference specific to the building. By collecting andreviewing existing records; conducting a walk-through inspection of the building; talking withmaintenance and facility engineers; and compilingdetailed data on the HVAC system, pollutant path-ways, pollutant sources and building occupancy, thefour key IAQ profile questions can be answered:

l.How was the building originally intended tofunction?

2. Is the building functioning as designed?

3. What changes in layout and use have occurredsince the original design and construction?

4. What changes may be needed to prevent futureIAQ problems from developing?

Once completed, the IAQ Profile will help identifypotential problem areas and prioritize budgets formaintenance and future modifications.

Odor investigation and abatement includes somemeasure of trial and error, and no two cases are alike.In some instances a relocation of chemicals will solvethe problem. However, some situations can requireventilation installation, process controls, or an airpollution system. With a building's IAQ Profile inhand, the organization can focus on the scent in

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question. Odor problems are typically easier to iden-tify and solve in a commercial facility compared toan industrial facility due to the limited number ofpotential odor sources.

ther the office or manufacturing facilities, no matterhow slight, must consider subsequent ventilationsystem modifications so as to guard against negativeconsequences to the air balances.

Assessing building air quality and odors inindustrial facilities

In addition to the odor sources listed for commercialsettings, industrial facilities can have further causesor sources for odor. The sources of an odor in an in-dustrial setting may include any of the sources listedabove for commercial facilities, plus the following:

• Vapors released from processes

• Accidental chemical spills

• Chemical reactions

• Raw material storage

• Process equipment maintenance

• Process waste materials

Typically, a light manufacturing facility has adjacentoffice space. Such cojoined buildings increase energyefficiency and fuel cost savings, but can also create ele-vated indoor air contaminant and odor levels, andcause increased worker complaints, illnesses, and sickdays. Because the air used in office environments isshared with their adjoining light industrial and manu-facturing plants, the approach to odor investigationsand abatement becomes even more complex and criti-cal. Factors such as the wide variety of prevalent chem-icals and the necessity for local exhaust ventilation toremove contaminants are of primary importance.

Manufacturing equipment requires well-designedand enclosed local exhaust ventilation to properlycapture contaminants by using the least air flow. Thelocal exhaust air flow should be matched with anequal amount of tempered make-up air to ensure ven-tilation system operational efficiency. The exhaustand makeup air systems should be operated to main-tain a slight negative pressure in the manufacturingplant relative to the office environment. This balancewill help prevent air being drawn into and contami-nating the office environment through doors, ceilingplenums, cracks, and other leakage points.

Another key factor to consider is the proximity of theexhaust stacks to outside air intakes. These shouldbe positioned to minimize the chances of contami-nated exhaust air being drawn into the air intakes ofthe office HVAC systems. Any modifications to ei-

Minimizing worker exposure to the chemicals thatare present in industrial facilities is regulated by theOccupational Safety and Health Administration(OSHA). Maintaining exposures below the regu-lated levels (Threshold Limit Values, as published bythe American Conference of Industrial Hygienistsand Permissible Exposure Limits established byOSHA) may not eliminate all unpleasant smells. Incases where air from the manufacturing area is al-lowed to enter the office area, odor problems mayarise even if the manufacturing area is in full compli-ance with the OSHA worker exposure levels.

Conducting the odor investigationOdor investigations for both commercial and indus-trial facilities should include the following tasks,conducted in roughly this order:

1. Interview people with knowledge of the odors,building systems, manufacturing systems, and / ormaterial storage to attempt to narrow down thepossibilities.

2. Review building documentation, including IAQProfile if available and Material Safety Data Sheetsfor suspected chemicals.

3. Conduct a site walk-through to attempt to identifythe sources of the odors.

4. Research odor thresholds for each of the chemicalsof concern. An odor threshold identifies the con-centration required for humans to register a chem-ical's scent. If a threshold is low, its scent would bedetectable at low concentrations in the air, while ahigher threshold would require the presence oflarger chemical quantities for its detection.

5. Develop a sampling plan, if necessary, to identifythe specific chemical compounds or classes ofcompounds responsible for the odors. Some com-mon sampling techniques include the following:

• Photoionization detectors to provide real-timemeasurement of volatile organic compounds(VOCs). These are used to survey the area andident i fy the locations where the odor isstrongest.

• Determination of VOCs in air collected in spe-cially prepared canisters and analyzed by gaschromatography/mass spectrometry. This isknown as Method TO-15.

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• Charcoal tubes and sample pumps to obtainmultiple samples at lower cost than TO-15 forconducting a VOC scan.

6. Isolate and identify the sources of the odors andstart developing abatement strategies.

7. Involve all interested parties in the assessment andthe proposed resolution to ensure agreement onthe problem and the solution.

Odor abatement

Once the source of the odor has been identified, thefacility must enact a solution or series of solutions.As previously stated, the complexity of these resolu-tions can vary. For example, in a scenario in whichtoluene was being stored in uncovered drums, thesolution could be as simple as sealing the drumswhenever they are not in use. If this does not resolvethe problem, an additional resolution, such as venti-lation of the storage area, may be required. However,in a more serious instance, such as where a newchemical process is vented to the outside is causingodors in the surrounding neighborhood, the facilitymight require a more costly and complex solution,such as the installation of an air pollution controlsystem for odor abatement. These odor abatementsystems include carbon adsorbers, wet scrubbers,and thermal oxidizers. While these systems can re-duce or eliminate the odors released into the atmos-phere, they require substantial time and money todesign and install. They also often require that airpermits be obtained from the regulatory agencyprior to installation.

The following examples of other odor abatementstrategies illustrate the wide variety of problems andsolutions for odors:

1. Substituting a less odorous chemical in a manufac-turing process

2. Cleaning up the area where a chemical spill led tothe odor

3. Improving the local exhaust ventilation systems atthe source of the odor

4. Modifying housekeeping practices to improvecleanliness and reduce the use of odorous cleaningmaterials

5. Redesigning the HVAC systems to minimize thepotential for drawing odors into the facility fromoutside

6. Conducting a mold remediation and eliminatingthe sources of water infiltration

7. Isolating waste materials from building occupants

Some odor-abatement strategies require follow-upactivities to prevent the reoccurrence of the odorproblem. These ongoing activities could include pe-riodic inspections, HVAC system maintenance, andworker training.

Conclusion

Odor investigations and abatement strategies varygreatly in scope and complexity. Commercial facili-ties have a wide variety of potential causes for un-pleasant odors. Industrial facilities have numerousadditional odor-producing activities associated withmanufacturing and waste disposal activities. Build-ing owners can be well served by the developmentof an Indoor Air Quality Profile for their facilities sothat when odor problems arise, their resolution canbe expedited.

For more complex odor mitigation projects, espe-cially those involving the installation of air pollutioncontrol systems or the modification of HVAC sys-tems, outside consulting and engineering assistanceare invaluable. ARC

Tom Petersen, PE, is president of Environmental andEngineering Solutions, Inc., Wyncote, PA; 215-881-9401; tom@eesolutions.net. Tom has more than 30 years ofenvironmental engineering and health and safety experi-ence in project management, process safety management,air quality compliance, strategic planning, and environ-mental control systems design. His services have includedwork in 22 states for the chemical, pharmaceutical, print-ing and surface coating, electronics, food, metals, automo-tive, and other industries.