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Question 1Indoor Environmental Consulting (domains not enumerated in source)

Which federal agency enforces the Toxic Substances Control Act (TSCA) in the United States?

  1. The Department of Housing and Urban Development
  2. The Occupational Safety and Health Administration
  3. The Environmental Protection Agency Correct answer.
  4. The Consumer Product Safety Commission

Explanation

TSCA is administered and enforced by the EPA, which regulates industrial chemicals including asbestos, lead, and PCBs. OSHA and CPSC have separate statutory mandates covering workplace safety and consumer products respectively.

Question 2Indoor Environmental Consulting (domains not enumerated in source)

A common threshold at which indoor carbon dioxide is often cited as a marker of inadequate ventilation is approximately:

  1. 400 ppm
  2. 5,000 ppm
  3. 10,000 ppm
  4. 1,000 ppm Correct answer.

Explanation

About 1,000 ppm CO2 above outdoor levels is widely used as an indicator that ventilation may be insufficient, though it is a proxy rather than a direct health standard. Outdoor CO2 is roughly 420 ppm, so 1,000 ppm signals limited fresh-air exchange.

Question 3Indoor Environmental Consulting (domains not enumerated in source)

Which particle size fraction is most often associated with deep lung deposition and is commonly measured in indoor air investigations?

  1. Coarse settled dust
  2. PM10
  3. Total suspended particulate
  4. PM2.5 Correct answer.

Explanation

PM2.5 refers to particles 2.5 micrometers and smaller, which penetrate to the alveoli and are the focus of most health-based indoor particulate assessments. Larger fractions deposit higher in the respiratory tract.

Question 4Indoor Environmental Consulting (domains not enumerated in source)

Radon is a decay product of which element?

  1. Mercury
  2. Uranium Correct answer.
  3. Arsenic
  4. Lead

Explanation

Radon-222 forms from the radioactive decay of radium, which is itself a decay product of uranium-238 found in soil and rock. It migrates into buildings through foundation openings.

Question 5Indoor Environmental Consulting (domains not enumerated in source)

In mold investigations, which condition is the primary driver of indoor fungal amplification?

  1. Elevated volatile organic compounds
  2. Sustained moisture availability Correct answer.
  3. Low air exchange rates alone
  4. High airborne particulate counts

Explanation

Fungi require moisture to grow; without a sustained water source, mold amplification does not occur regardless of other conditions. Moisture control is therefore the central remediation principle.

Question 6Indoor Environmental Consulting (domains not enumerated in source)

Which document type is typically used to record field observations, sampling locations, and instrument readings during an indoor environmental assessment?

  1. Chain-of-custody form
  2. Remediation work plan
  3. Laboratory report
  4. Field log or field notes Correct answer.

Explanation

Field logs capture contemporaneous observations, locations, and instrument readings that support the assessment. Chain-of-custody forms track sample handling, lab reports present analytical results, and work plans describe planned actions.

Question 7Indoor Environmental Consulting (domains not enumerated in source)

Which of the following is an example of a point source of indoor air contamination?

  1. A leaking underground storage tank affecting a neighborhood
  2. Regional photochemical smog
  3. Outdoor traffic exhaust entering through a window
  4. A malfunctioning gas stove in a kitchen Correct answer.

Explanation

A point source is a single identifiable emission location, such as one appliance releasing combustion byproducts. The other examples are diffuse or area-wide sources rather than discrete indoor points.

Question 8Indoor Environmental Consulting (domains not enumerated in source)

What does the acronym HVAC stand for?

  1. Heating, Vapor, and Airflow Circulation
  2. Humidity, Vapor, and Air Control
  3. Humidification, Ventilation, and Air Cleaning
  4. Heating, Ventilation, and Air Conditioning Correct answer.

Explanation

HVAC refers to heating, ventilation, and air conditioning systems, which are central to indoor environmental quality because they govern thermal comfort and air distribution. The other options are not standard industry terms.

Question 9Indoor Environmental Consulting (domains not enumerated in source)

During a walkthrough of a building with reported musty odors, which investigative step best follows initial occupant interviews?

  1. Collecting air samples for volatile organic compounds before inspecting the space
  2. Recommending immediate demolition of all porous materials
  3. Performing a systematic visual inspection for moisture and water damage Correct answer.
  4. Issuing a clearance report based on occupant complaints

Explanation

A systematic visual inspection for moisture, staining, and visible growth is the appropriate next step after interviews, because it identifies potential sources before sampling decisions are made. Sampling without source identification is generally inefficient and harder to interpret.

Question 10Indoor Environmental Consulting (domains not enumerated in source)

A consultant measures 1,200 ppm CO2 in a conference room with 20 occupants and a known outdoor level of 420 ppm. What does this result most strongly suggest?

  1. The room is contaminated with mold spores
  2. The ventilation rate is likely inadequate for the occupancy Correct answer.
  3. The room has adequate ventilation per occupant
  4. A combustion appliance is definitely leaking

Explanation

An indoor-outdoor CO2 differential of roughly 780 ppm, with a total above 1,000 ppm, indicates that occupant-generated CO2 is accumulating, which points to inadequate ventilation for the occupancy. CO2 is a ventilation indicator, not a direct mold or combustion test.

Question 11Indoor Environmental Consulting (domains not enumerated in source)

An investigator collects a non-viable spore trap sample in a room and an outdoor control. Which interpretation approach is most defensible?

  1. Judge the indoor sample against a single universal numeric standard
  2. Ignore the outdoor sample if indoor growth is visible
  3. Report only total spore count without species identification
  4. Compare indoor and outdoor spore types and concentrations Correct answer.

Explanation

Indoor spore data are interpreted relative to outdoor background and to the types present, since no single universal numeric standard exists. Comparing composition and concentration to outdoor controls is the standard interpretive approach.

Question 12Indoor Environmental Consulting (domains not enumerated in source)

A building occupant reports headaches and irritation that resolve on weekends and recur on workdays. Which pattern is most consistent with?

  1. A building-related illness with a confirmed diagnosis
  2. Carbon monoxide poisoning requiring hospitalization
  3. Chronic radon exposure
  4. A sick building syndrome-type complaint pattern Correct answer.

Explanation

Symptoms that improve away from the building and recur on return are characteristic of sick building syndrome-type complaints, which lack a single confirmed clinical cause. Building-related illness, by contrast, involves identifiable disease and a specific agent.

Question 13Indoor Environmental Consulting (domains not enumerated in source)

Which sampling approach is generally preferred when the goal is to characterize long-term average concentrations of a contaminant in an occupied space?

  1. Integrated sampling over an extended period Correct answer.
  2. One instantaneous reading at the doorway
  3. A single short-term grab sample
  4. Sampling only during unoccupied hours

Explanation

Integrated sampling over time yields a time-weighted average that better represents long-term exposure than a single grab sample. Short-term samples capture only a moment and may miss variability.

Question 14Indoor Environmental Consulting (domains not enumerated in source)

In a chain-of-custody procedure, which element is essential for maintaining sample integrity?

  1. Recording each transfer with signatures, dates, and times Correct answer.
  2. Storing samples at room temperature regardless of method
  3. Combining samples from different locations into one container
  4. Removing sample labels to protect occupant privacy

Explanation

Chain of custody documents every transfer of a sample with signatures, dates, and times so its integrity can be demonstrated. Proper storage per method and unique labeling are also required.

Question 15Indoor Environmental Consulting (domains not enumerated in source)

A water-damaged carpet has been wet for 72 hours and shows visible mold growth. What is the most appropriate initial recommendation?

  1. Install a dehumidifier and monitor without removal
  2. Remove and discard the affected porous material Correct answer.
  3. Seal the carpet with an encapsulant coating
  4. Clean with a disinfectant and return to service

Explanation

Porous materials with visible mold growth after extended wetting generally cannot be reliably cleaned and should be removed. Remediation should also address the moisture source and contain the work area.

Question 16Indoor Environmental Consulting (domains not enumerated in source)

Which factor most directly affects the interpretation of formaldehyde results in a newly constructed office?

  1. The outdoor pollen count
  2. The age of the building and presence of new pressed-wood products Correct answer.
  3. The number of windows on the south facade
  4. The building's radon potential zone

Explanation

Formaldehyde emissions are strongly associated with new pressed-wood products and off-gassing from furnishings and finishes, so building age and material content are key interpretive factors. Other listed factors do not directly drive formaldehyde concentrations.

Question 17Indoor Environmental Consulting (domains not enumerated in source)

Which of the following best describes the purpose of a negative-pressure containment during mold remediation?

  1. To increase airflow into the work area
  2. To raise humidity in the work area
  3. To prevent contaminants from migrating to occupied spaces Correct answer.
  4. To eliminate the need for personal protective equipment

Explanation

Negative-pressure containment keeps the work area at lower pressure than surrounding spaces, so air flows inward and contaminants are less likely to escape. It does not remove the need for PPE or moisture control.

Question 18Indoor Environmental Consulting (domains not enumerated in source)

A consultant is asked to evaluate a complaint of diesel odor in an office adjacent to a loading dock. Which initial data-gathering approach is most useful?

  1. Measuring formaldehyde in the lobby
  2. Testing for radon in the basement
  3. Reviewing building pressure relationships and dock activity schedules Correct answer.
  4. Collecting a single spore trap sample indoors

Explanation

Diesel odor intrusion from a loading dock is typically driven by pressure differentials and vehicle activity, so reviewing pressure relationships and schedules targets the likely pathway. Spore, radon, and formaldehyde testing do not address the identified odor source.

Question 19Indoor Environmental Consulting (domains not enumerated in source)

Which measurement best characterizes the performance of a ventilation system in delivering outdoor air to occupants?

  1. Filter pressure drop
  2. Return air temperature
  3. Static pressure across the supply fan
  4. Outdoor air intake flow rate per occupant Correct answer.

Explanation

Outdoor air flow rate per occupant directly reflects the quantity of fresh air delivered relative to occupancy, which is the basis of ventilation standards. The other measures describe system operation but not delivered fresh air per person.

Question 20Indoor Environmental Consulting (domains not enumerated in source)

Which of the following best describes the role of a blank sample in an indoor air investigation?

  1. It measures occupant exposure directly
  2. It documents background or handling contamination Correct answer.
  3. It identifies the contaminant of concern
  4. It replaces the need for outdoor controls

Explanation

A blank sample is processed alongside field samples without the target collection step to reveal contamination introduced during handling, transport, or analysis. It supports data quality but does not identify contaminants or measure exposure.

Question 21Indoor Environmental Consulting (domains not enumerated in source)

An investigator finds elevated moisture readings in drywall but no visible growth and no musty odor. What is the most appropriate recommendation?

  1. Apply an antimicrobial coating and close the wall
  2. No action is needed because growth is not visible
  3. Sample for radon before addressing moisture
  4. Find and correct the moisture source and dry the materials Correct answer.

Explanation

Elevated moisture without visible growth is a pre-condition for mold amplification, so the correct response is to identify and correct the water source and dry the materials. Waiting for visible growth allows contamination to develop.

Question 22Indoor Environmental Consulting (domains not enumerated in source)

A consultant must decide whether to sample for lead-based paint in a pre-1978 home. Which regulatory context most directly frames this decision?

  1. The Safe Drinking Water Act
  2. The Resource Conservation and Recovery Act
  3. The Lead Disclosure Rule and related lead hazard regulations Correct answer.
  4. The Clean Air Act

Explanation

Lead-based paint in pre-1978 housing is governed by disclosure and lead hazard regulations that frame inspection and sampling decisions. The other statutes address air, water, and waste, respectively.

Question 23Indoor Environmental Consulting (domains not enumerated in source)

Which of the following best explains why outdoor control samples are collected during an indoor fungal assessment?

  1. To satisfy a requirement that all samples be paired
  2. To calibrate the moisture meter
  3. To establish a local background against which indoor results can be compared Correct answer.
  4. To determine the building's thermal performance

Explanation

Outdoor controls establish the ambient spore profile and concentration for the site and season, allowing indoor results to be interpreted in context. They do not calibrate instruments or assess thermal performance.

Question 24Indoor Environmental Consulting (domains not enumerated in source)

A building has a history of intermittent roof leaks and occupants report symptoms only during rainy periods. Which investigative conclusion is best supported?

  1. A combustion byproduct problem
  2. A moisture-driven indoor environmental problem tied to envelope failures Correct answer.
  3. A seasonal allergy unrelated to the building
  4. A chronic radon problem

Explanation

Symptoms correlating with rain and a history of leaks point to a moisture-driven problem linked to building envelope failures. This pattern does not support radon or combustion explanations, and building correlation argues against an unrelated seasonal allergy.

Question 25Indoor Environmental Consulting (domains not enumerated in source)

When interpreting volatile organic compound results from a building with new furnishings, which factor most complicates comparison to published background ranges?

  1. The outdoor temperature at the time of sampling
  2. The analyst's choice of reporting units
  3. The wide variability in source strength and ventilation conditions Correct answer.
  4. The number of samples collected

Explanation

VOC concentrations vary widely with source strength, product age, temperature, and ventilation, so published background ranges are broad and comparison is inherently uncertain. Reporting units and sample counts can be standardized but do not resolve source variability.

Question 26Indoor Environmental Consulting (domains not enumerated in source)

Which parameter is most commonly measured with a non-dispersive infrared (NDIR) sensor during an indoor air quality investigation?

  1. Airborne particulate matter smaller than 2.5 micrometers
  2. Airborne fungal spore count
  3. Carbon dioxide concentration Correct answer.
  4. Formaldehyde concentration

Explanation

NDIR sensors are widely used for real-time carbon dioxide measurement because CO2 absorbs infrared light at a specific wavelength. This makes them a standard tool for assessing ventilation adequacy and occupancy effects. Other contaminants require different detection methods such as microscopy, colorimetric tubes, or light scattering.

Question 27Indoor Environmental Consulting (domains not enumerated in source)

A consultant is planning an indoor air quality assessment for a building with reported odors. Which action is most appropriate before collecting any air samples?

  1. Review the building's HVAC maintenance records
  2. Collect a single 24-hour integrated sample for volatile organic compounds
  3. Conduct a walkthrough inspection to identify potential sources and ventilation issues Correct answer.
  4. Interview all occupants to determine their symptoms

Explanation

A systematic walkthrough is the foundation of any indoor air quality investigation because it identifies pollution sources, ventilation pathways, and moisture problems that guide sampling strategy. Sampling without prior inspection can waste resources and miss the actual cause. Interviews and records are useful but secondary to direct observation.

Question 28Indoor Environmental Consulting (domains not enumerated in source)

Which of the following is a primary purpose of a moisture meter during a building moisture assessment?

  1. To detect elevated moisture content in building materials Correct answer.
  2. To measure the airborne concentration of mold spores
  3. To measure the ventilation rate of a room
  4. To determine the type of mold growing on a surface

Explanation

A moisture meter is used to identify elevated moisture in materials such as drywall, wood, and concrete, which can indicate hidden water damage or conditions conducive to mold growth. It does not identify mold species or measure airborne contaminants. Ventilation rate is measured with airflow instruments.

Question 29Indoor Environmental Consulting (domains not enumerated in source)

A consultant is interpreting carbon dioxide measurements in an office. The outdoor CO2 concentration is 400 ppm, and the indoor concentration is 1,000 ppm. What does this indicate about the ventilation rate per person if the CO2 generation rate is assumed constant?

  1. The ventilation rate is approximately half of what it would be if indoor CO2 were 700 ppm Correct answer.
  2. The ventilation rate cannot be estimated without knowing the number of occupants
  3. The ventilation rate is excessive because the indoor-outdoor difference is 600 ppm
  4. The ventilation rate is adequate because indoor CO2 is below 1,000 ppm

Explanation

Under steady-state conditions, the indoor-outdoor CO2 difference is inversely proportional to the ventilation rate per person. A difference of 600 ppm (1000-400) corresponds to roughly half the ventilation rate of a 300 ppm difference (700-400). Thus, the rate is approximately half of that at 700 ppm. The number of occupants is not needed for the per-person rate if the generation rate per person is known.

Question 30Indoor Environmental Consulting (domains not enumerated in source)

During a mold assessment, a consultant collects an air sample using a spore trap. Which factor is most critical to ensure the sample is representative of the area being assessed?

  1. Using a sterile swab to collect a surface sample concurrently
  2. Calibrating the pump to the manufacturer's specified flow rate Correct answer.
  3. Collecting the sample at eye level in the center of the room
  4. Collecting the sample for a duration of at least 8 hours

Explanation

Spore trap samplers rely on a specific flow rate to impact particles onto the collection surface efficiently. Calibrating the pump to the specified flow rate ensures the sample volume is accurate and the collection efficiency is as intended. Sample location, duration, and concurrent surface sampling are important but secondary to proper flow calibration.

Question 31Indoor Environmental Consulting (domains not enumerated in source)

A consultant is assessing a room with reported musty odors. The HVAC system is operating, and no visible mold is found. Which action is most appropriate to investigate potential hidden mold growth?

  1. Collect a bulk sample of the carpet
  2. Collect an air sample for volatile organic compounds
  3. Increase the ventilation rate and reassess after 24 hours
  4. Measure moisture content in building materials and inspect concealed spaces Correct answer.

Explanation

Musty odors often indicate hidden mold growth in concealed spaces such as wall cavities or above ceiling tiles. Measuring moisture content and inspecting those areas can reveal the source. Bulk sampling of carpet, increasing ventilation, or VOC sampling does not directly locate hidden mold.

Question 32Indoor Environmental Consulting (domains not enumerated in source)

In a building with a history of water intrusion, a consultant finds elevated airborne mold spores indoors compared to outdoors. Which factor most strongly supports the conclusion that the indoor mold source is active?

  1. The presence of hyphal fragments in the indoor sample
  2. The total spore count indoors is higher than the outdoor count
  3. The indoor/outdoor ratio for a marker species is greater than 1 Correct answer.
  4. The detection of both Penicillium and Aspergillus spores indoors

Explanation

A marker species is one that is typically rare outdoors but can grow indoors on wet materials. An indoor/outdoor ratio greater than 1 for such a species indicates an indoor amplification source. Total spore counts or presence of common genera can be influenced by outdoor levels and are less specific.

Question 33Indoor Environmental Consulting (domains not enumerated in source)

A consultant is designing a sampling plan for formaldehyde in a newly constructed office. Which sampling approach is most appropriate for determining compliance with an occupational exposure limit?

  1. Collect a full-shift personal sample Correct answer.
  2. Collect a grab sample during peak occupancy
  3. Collect an area sample near the HVAC return
  4. Collect a short-term sample during the first hour of occupancy

Explanation

Occupational exposure limits are typically based on full-shift personal sampling to represent the worker's average exposure over the workday. Grab samples or short-term samples may not capture the full exposure profile. Area samples do not account for personal breathing zone concentrations.

Question 34Indoor Environmental Consulting (domains not enumerated in source)

A consultant is interpreting VOC results from a building with new furnishings. Which factor most complicates the comparison of indoor VOC concentrations to health-based guidelines?

  1. The lack of speciation of individual compounds
  2. The use of a summa canister for sample collection
  3. The absence of outdoor VOC measurements
  4. The variability of VOC emissions over time due to off-gassing Correct answer.

Explanation

New furnishings emit VOCs that decrease over time as off-gassing occurs, so concentrations can vary significantly depending on when the sample is collected relative to installation. This temporal variability complicates comparison to guidelines that assume steady-state or long-term exposure. Outdoor measurements and speciation are important but do not inherently complicate the comparison as much as temporal variability.

Question 35Indoor Air Quality Assessment and Investigation

Which indoor air pollutant is most commonly measured with a photoionization detector (PID) during a building investigation?

  1. Airborne fungal spores
  2. Carbon monoxide
  3. Carbon dioxide
  4. Total volatile organic compounds Correct answer.

Explanation

A PID uses ultraviolet light to ionize molecules and is widely used as a screening tool for total VOCs; readings are expressed as a total response rather than a single compound. CO2 and CO are typically measured with nondispersive infrared and electrochemical sensors, respectively. Fungal spores require microscopic or culture-based sampling.

Question 36Indoor Air Quality Assessment and Investigation

In a typical occupied office, what does an elevated indoor CO2 concentration most directly indicate?

  1. A carbon monoxide leak from combustion
  2. Excessive airborne particulate matter
  3. Inadequate outdoor air ventilation per occupant Correct answer.
  4. High concentrations of formaldehyde

Explanation

CO2 is a metabolic product of occupants, so rising concentrations above outdoor levels indicate that occupant-generated CO2 is accumulating faster than ventilation dilutes it. It is used as a proxy for ventilation adequacy, not as a direct measure of other pollutants.

Question 37Indoor Air Quality Assessment and Investigation

What is the primary purpose of collecting a baseline outdoor air sample during an indoor air quality investigation?

  1. To determine the building's air exchange rate
  2. To satisfy the building's fire code requirements
  3. To establish reference concentrations for comparison with indoor results Correct answer.
  4. To calibrate the building's HVAC controls

Explanation

Outdoor samples provide a reference against which indoor concentrations can be compared, helping distinguish pollutants entering from outside from those generated indoors. This supports source attribution and interpretation of indoor results.

Question 38Indoor Air Quality Assessment and Investigation

During an IAQ walkthrough, which observation most strongly suggests a moisture problem that could support microbial growth?

  1. A faint odor of cleaning products near a supply diffuser
  2. Persistent condensation on window frames and discolored ceiling tiles Correct answer.
  3. New carpeting installed in a corridor
  4. A slightly higher-than-average room temperature

Explanation

Persistent condensation and water staining indicate sustained moisture, the key condition for microbial amplification. Visual evidence of moisture, staining, or discoloration should prompt further moisture and microbial assessment.

Question 39Indoor Air Quality Assessment and Investigation

Which size fraction of airborne particulate matter is most appropriate to measure when evaluating respirable particles that penetrate to the deep lung?

  1. Coarse road dust
  2. PM2.5 Correct answer.
  3. Total suspended particulate
  4. PM10

Explanation

PM2.5 refers to particles 2.5 micrometers and smaller, which penetrate deeply into the respiratory tract and are the standard metric for fine respirable particles. PM10 includes larger particles that deposit higher in the airways.

Question 40Indoor Air Quality Assessment and Investigation

An investigator places an integrating sampler in the center of an open office at breathing height for eight hours. Which sampling objective does this best support?

  1. Identifying the exact location of a small spill
  2. Measuring peak concentrations from a momentary event
  3. Estimating average occupant exposure over the work shift Correct answer.
  4. Determining the building's air exchange rate

Explanation

Fixed-location integrating sampling over a full shift estimates the average concentration to which occupants are exposed. It does not capture spatial variability or short-term peaks and is not a tracer gas method.

Question 41Indoor Air Quality Assessment and Investigation

Which pollutant is a colorless, odorless gas produced by incomplete combustion and is a recognized cause of indoor poisoning?

  1. Nitrogen dioxide
  2. Carbon dioxide
  3. Carbon monoxide Correct answer.
  4. Ozone

Explanation

Carbon monoxide is a colorless, odorless product of incomplete combustion and is a leading cause of indoor poisoning from faulty combustion appliances. CO2 has a characteristic association with occupancy, ozone has a sharp odor, and NO2 has a pungent odor.

Question 42Indoor Air Quality Assessment and Investigation

Which document type is the standard method for recording chain-of-custody information for air samples sent to a laboratory?

  1. An interview transcript
  2. An equipment calibration log
  3. A floor plan sketch
  4. A chain-of-custody form Correct answer.

Explanation

A chain-of-custody form documents sample handling, transfer, and receipt to preserve evidentiary integrity. Calibration logs, floor plans, and interview notes serve different purposes in the investigation record.

Question 43Indoor Air Quality Assessment and Investigation

An occupant reports symptoms that begin shortly after arriving at work and resolve on weekends. Which investigation approach best tests the hypothesis of a workplace exposure?

  1. Measure outdoor pollen counts for the same period
  2. Compare symptom timing with building occupancy and ventilation schedules Correct answer.
  3. Review the building's fire inspection records
  4. Sample only the parking garage

Explanation

Temporal patterns that track occupancy and ventilation schedules support a workplace-related exposure hypothesis. Comparing symptom timing with building operation helps distinguish building-related from non-building causes.

Question 44Indoor Air Quality Assessment and Investigation

During a tracer gas decay test, the concentration falls to 37 percent of its initial value in 2 hours. What is the approximate air exchange rate?

  1. 3.7 air changes per hour
  2. 1.0 air changes per hour
  3. 0.5 air changes per hour Correct answer.
  4. 2.0 air changes per hour

Explanation

The 37 percent point corresponds to one time constant, so the decay constant equals 1 divided by the elapsed time. Falling to 37 percent in 2 hours gives a decay constant of 0.5 per hour, or 0.5 air changes per hour.

Question 45Indoor Air Quality Assessment and Investigation

A CO2 reading of 1,200 ppm is measured in a conference room with an outdoor concentration of 400 ppm. Using the steady-state mass balance with a per-person CO2 generation rate of 0.005 L/s and assuming perfect mixing, what outdoor air supply per person is approximately indicated?

  1. About 30 L/s per person
  2. About 20 L/s per person
  3. About 6 L/s per person Correct answer.
  4. About 12 L/s per person

Explanation

The steady-state relationship is generation rate divided by the difference between indoor and outdoor CO2 concentrations: 0.005 L/s divided by 0.0008 equals about 6 L/s per person. This illustrates how CO2 can be used to estimate ventilation per occupant.

Question 46Indoor Air Quality Assessment and Investigation

An investigator finds visible mold on gypsum board below a leaking pipe. Which combination of actions is most appropriate?

  1. Apply a biocide fog and take no further action
  2. Fix the moisture source, remove or clean affected materials, and verify with moisture measurements Correct answer.
  3. Seal the area with plastic and continue occupancy without repair
  4. Increase the thermostat setpoint and re-inspect in a year

Explanation

Microbial growth requires moisture, so correcting the water source is essential and must precede or accompany remediation of affected materials. Post-remediation moisture verification confirms the fix was effective.

Question 47Indoor Air Quality Assessment and Investigation

A formaldehyde measurement is taken in a newly furnished office. Which factor most affects the interpretation of the result?

  1. The number of windows in the room
  2. The age and temperature of the furnishings and the sampling duration Correct answer.
  3. The color of the carpet
  4. The brand of the HVAC filter

Explanation

Formaldehyde emissions from pressed-wood products and furnishings decline with age and increase with temperature and humidity, so these factors plus sampling duration affect interpretation. Color, window count, and filter brand are not primary determinants.

Question 48Indoor Air Quality Assessment and Investigation

Which sampling strategy is most appropriate for investigating a complaint of a localized solvent odor near a specific workstation?

  1. A single whole-building rooftop sample
  2. A one-time outdoor sample far from the building
  3. Area sampling near the suspected source with concurrent time-activity records Correct answer.
  4. A 30-day passive sample at the building entrance

Explanation

Localized complaints require sampling near the suspected source and correlating results with occupant activities and timing. Whole-building or distant outdoor samples would dilute or miss the localized source.

Question 49Indoor Air Quality Assessment and Investigation

During an investigation, occupants report headaches that worsen as the day progresses and improve when they leave the building. Which finding would most strongly support a building-related cause?

  1. Symptoms correlate with outdoor weather but not with indoor conditions
  2. Symptom prevalence is higher in a work area with poor ventilation than in a well-ventilated area Correct answer.
  3. Symptoms resolve when occupants change desks within the same room
  4. Symptoms are equally common among visitors and staff

Explanation

A dose-response pattern in which symptoms track a ventilation or exposure gradient within the building supports a building-related cause. Equal prevalence among visitors, correlation with outdoor weather, or resolution with a desk change within the same room points away from a building cause.

Question 50Indoor Air Quality Assessment and Investigation

Which instrument is best suited for real-time screening of fine particulate matter during an IAQ walkthrough?

  1. An electrochemical CO sensor
  2. A light-scattering particle counter Correct answer.
  3. A nondispersive infrared CO2 meter
  4. A photoionization detector

Explanation

Light-scattering particle counters provide real-time estimates of particulate concentrations and size fractions. PIDs measure VOCs, NDIR meters measure CO2, and electrochemical sensors measure CO.