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IAQ Analysis: Updating the Arsenal
Indoor quality can change quickly, depending on facility operations, building materials, water infiltration and other building-use factors. And even if a facility’s indoor air quality (IAQ) satisfies guidelines from the U.S. Environmental Protection Agency (EPA) and the Occupational Safety and Health Administration (OSHA), maintenance and engineering managers still might face IAQ issues that generate complaints and concerns from building occupants.
Especially severe IAQ issues can arise when chemical, biological, or radioactive (CBR) components are transmitted through the air. Depending on the type of building, CBR contaminants might be either isolated or readily transmitted. One of the most important considerations in this regard is the ability to zone a ventilation system if a CBR is detected.
The general cleanliness of ventilation systems and building interstitial spaces — elevator shafts, core building vertical air return plenums, horizontal air plenums, etc. — also will affect a facility’s ability to quickly respond effectively to a CBR attack.
Whether a consultant or in-house personnel perform an IAQ analysis, managers must be aware of the latest generation of analysis and monitoring tools in order to make proper decisions related to responding to IAQ problems and preventing them in the future.
Consultants performing IAQ investigations use specific terminology to describe the contaminants under investigation and the tools they use for an IAQ analysis. A discussion of both the contaminants and the analysis technology can help managers develop an effective strategy.
Particulates such as asbestos, cellulose, lead, cadmium and spores present concerns because they are toxic upon inhalation. Particulate transfer throughout a building envelope also is a concern because very small particles of dust or dirt can provide a mode of transportation for other contaminants. The particulates’ porous surfaces can absorb or adsorb liquids and gases, and the resulting particulate becomes a combination of the original and whatever is now along for the ride.
Radon offers a good example of this phenomenon. If a small piece of dust absorbs radon gas and then is inhaled, the particulate travels to the lung and stays in place. Over time, the radon gas in the lung will go through a radioactive decay process. The energy it emits can damage the cellular DNA of the surrounding lung tissue. So the particulate transportation that led to the radon-gas-laced dust particulate’s presence in the lung substantially contributed to the risk.
Reducing airborne transmittal of dust and dirt particles will substantially decrease a building’s overall vulnerability to both IAQ issues and CBR-based attacks. Unfortunately, ventilation systems that are difficult to clean can hamper this control and contribute to the particulate loading of a building.
A case in point is a particulate that becomes part of a room’s air stream because lined ductwork has deteriorated. The telltale black fanning pattern around supply air ducts is one clue that either ductwork lining is deteriorating or that mold is growing on the ductwork lining.
One of the first types of sampling conducted for an IAQ study helps determine particulate levels. This sampling uses a small filter cassette. Air is drawn toward the cassette, and particulate riding in the air is filtered out onto a small paper-like membrane. Investigators use similar approaches to sample for mold spore or vegetative structure particulate. Special filter cassettes are used to trap mold spores on a tape-like surface or on agar.
Investigators also use various photoelectric, real-time systems to determine particulate loading. They can even connect these systems to an intranet or the internet to provide information on particulate levels. But baseline and incremental industrial hygiene sampling is necessary to assure that these remote-monitoring devices provide an accurate picture.
Volatiles are chemicals that readily change from liquid to gas at room temperature. Gases that remain gases at room temperature also are called volatiles. If these chemicals contain a carbon atom, they are referred to as volatile organic compounds (VOC).
An example is perfume, which is transmitted as liquid aerosol from a perfume bottle. But as the perfume becomes an aerosol mist, some of it will become a gas. This process is aided by application of the perfume to human skin, which warms the perfume.
From a maintenance perspective, volatiles randomly emitted through building material degradation create additional concerns for managers. Formaldehyde from paneling or compressed wood, various chemicals from new carpet, and general use of volatiles in cleaning products all can contribute to the overall volatile contaminant loading.
Instrumentation used to determine the presence of volatiles relies on either detecting the gas in the air in real time or trapping it for detection later. Real-time detection is accomplished using photoelectric energy to break the chemical into components.
The most common instrument for this task is a photoionization detector (PID). The hand-held instrument can detect at the parts-per-billion level, which often is required for IAQ studies where its presence is below OSHA’s permissible exposure levels. PIDs do not, however, identify the type of volatile, only that one is present. Identifying the type and source requires further historical investigation of contaminant possibilities or analysis. Devices that trap VOCs for analysis include:
- colorimetric tubing
- sorbent tubing packed with silica gel or activated charcoal
- special containers — bags, vapor badges, and canisters — to hold the VOCs until a color change or another type of analysis occurs.
IAQ investigators use oxygen- and combustible-gas indicators, as well as toxin sensors, with real-time instrumentation to determine levels of oxygen, flammable and combustible gases, and toxins in an environment. These instruments commonly are used for suspected natural-gas leaks .
Their use in IAQ investigations focuses on levels of oxygen, carbon dioxide, carbon monoxide, and various toxins in the air. These instruments provide a percentage determination of oxygen levels. When oxygen levels are sufficient for proper lower explosive level (LEL) detection, investigators can use the sensors to predict potentially flammable, combustible and explosive hazards.
Understanding how to use this instrument is crucial, and training specific to the types of flammable and combustible atmospheres is extremely important. Various toxin sensors also can be placed in these instruments. Levels of detection vary, and choices of toxin sensors should be made based on knowledge of facilities’ likely contaminants of concern.
Semi-volatile organic compounds (SVOC), such as polycyclic bi-phenyls, polynuclear aromatic hydrocarbons, dioxins, furans, and pesticides present unique challenges. The term semi-volatile describes chemicals that do not normally become volatile gases at room temperature. These chemicals can enter the air stream through a variety of mechanisms. The most prevalent mechanism occurs when they are dispersed as adsorbed or absorbed particulate contaminants.
Heating mechanisms, such as smoking, direct heating of semi-volatiles, burning plastic, and chemical use requiring semi-volatile application in a heated state — such as asphalt applications — contribute to the overall dispersion of semi-volatiles.
Semi-volatiles cannot be measured in real time. Instead, investigators can use collection through specialized filtration devices and follow-up laboratory analysis.
Acid Gases or Caustics
Acid gases and caustics can spread into the air during the use of cleaning and water-treatment chemicals. As with volatiles, acid gases can stick to and be transported by particulates. Investigators can use real-time instrumentation to determine if spills have occurred on surfaces. For this test, investigators use pH or litmus paper.
Transmitting acid gases or caustics to the air and detecting them requires colorimetric tubes, impingers — i.e., bubblers — or sorbent tubes. Of these, only colorimetric tubes give real-time information. Transmission of these chemicals usually provides very good warning properties, since acute effects include tearing up of the eyes, skin burns, and coughing.
From an IAQ perspective, detection might follow effect. During operations and maintenance tasks, both respiratory and dermal effects are of concern. Consequently, using cleaning agents must follow site-specific standard operating procedures based on these material safety data sheets and other information.
Monitoring a building’s status during normal operations provides an IAQ baseline, which indicates the expected levels of airborne chemicals and biologicals. Certain instances also might require radioactive agent monitoring.
Investigators can evaluate the success of their activities through the use of air-quality monitoring. Through discussion with consultants, managers might choose monitoring instrumentation that provides real-time information on building status.
Other forms of IAQ monitoring require coordinated investigations involving maintenance, operation, consultant and laboratory personnel. Knowing these options will be invaluable in the event of a CBR attack, both to determine the building status and evaluate the system recovery as decontamination proceeds.
Martha Boss is a practicing Certified Industrial Hygienist and a Certified Safety Professional with more than 16 years experience in industrial hygiene, facility management support, due diligence, safety engineering, emergency response, and risk-management planning. She supports building decontamination efforts worldwide for URS — www.urscorp.com — a major U.S. design and engineering firm.