Download ASCS Practice Exam.. and more Exams Technology in PDF only on Docsity!
Question 1. Which indoor air contaminant is most associated with allergic reactions and asthma symptoms? A) Carbon monoxide B) Pet dander C) Ozone D) Carbon dioxide Answer: B) Pet dander Explanation: Pet dander consists of tiny skin flakes from animals with fur or feathers, which are common allergens that trigger allergic reactions and asthma symptoms. Question 2. How does a dirty evaporator coil in an HVAC system primarily affect energy consumption? A) It increases airflow, reducing energy use. B) It causes the system to work harder, increasing energy consumption. C) It has no effect on energy efficiency. D) It decreases the need for filtration. Answer: B) It causes the system to work harder, increasing energy consumption. Explanation: Dirt on coils insulates the heat exchange surfaces, reducing efficiency and forcing the system to run longer to achieve desired conditions, thus increasing energy use. Question 3. Which component of an HVAC system is primarily responsible for mixing outdoor and return air? A) Air Handling Unit (AHU) mixing box B) Thermostat C) Fan coil unit D) Exhaust fan Answer: A) Air Handling Unit (AHU) mixing box Explanation: The mixing box within an AHU combines outdoor fresh air with return air to maintain indoor air quality and temperature control. Question 4. Which type of duct material is most flexible and easy to install but may have lower thermal insulation properties? A) Sheet metal B) Fiberglass ductboard C) Flexible ducting D) Rigid PVC Answer: C) Flexible ducting Explanation: Flexible ducting is made of a wire-reinforced plastic or metal core covered with insulation and flexible outer material, offering ease of installation but less insulation effectiveness. Question 5. During a visual inspection, a technician notices mold growth on the interior surface of an air duct. What is the most appropriate initial step? A) Immediately replace the ductwork B) Document the finding and recommend a cleaning plan C) Apply chemical biocides without further assessment D) Seal the duct to prevent further contamination Answer: B) Document the finding and recommend a cleaning plan Explanation: Proper documentation and planning are essential; immediate replacement or chemical application should follow assessment, not precede it.
Question 6. What is a common cause of microbial contamination in HVAC systems? A) Use of high-quality filters B) Excessive airflow C) Moisture intrusion and poor drainage D) Over-cleaning of filters Answer: C) Moisture intrusion and poor drainage Explanation: Moisture creates an environment conducive to microbial growth, leading to mold and bacteria proliferation within the system. Question 7. Which of the following best describes the purpose of a MERV rating in filters? A) It indicates the filter's lifespan. B) It measures the filter’s ability to remove particles of specific sizes. C) It denotes the filter’s chemical resistance. D) It reflects the filter’s airflow rate. Answer: B) It measures the filter’s ability to remove particles of specific sizes. Explanation: MERV (Minimum Efficiency Reporting Value) ratings quantify a filter’s effectiveness at capturing particles of different sizes, with higher ratings indicating better filtration. Question 8. Prior to cleaning, which action is most critical for establishing proper containment and safety? A) Turning off all electrical power B) Establishing negative pressure in the work area C) Removing all filters from the system D) Filling the ductwork with cleaning solutions Answer: B) Establishing negative pressure in the work area Explanation: Negative pressure containment prevents contamination from spreading outside the work zone during cleaning activities. Question 9. Which is the primary health concern associated with the inhalation of volatile organic compounds (VOCs) in indoor environments? A) Skin irritation only B) Respiratory issues and potential long-term health effects C) Immediate allergic reactions only D) Noise-induced hearing loss Answer: B) Respiratory issues and potential long-term health effects Explanation: VOCs can cause short-term respiratory irritation and long-term health problems, including carcinogenic effects, especially with prolonged exposure. Question 10. Which component is most likely to be affected by contamination buildup that can lead to decreased airflow and system efficiency? A) Thermostat B) Return air grille C) Supply fan motor D) Condensate drain line Answer: B) Return air grille Explanation: Dust, debris, and microbial growth can accumulate on return air grilles, obstructing airflow and reducing system efficiency. Question 11. When assessing a contaminated HVAC system, what is a key sign of microbial growth? A) Bright white stains
D) The number of occupants only Answer: B) The specific contamination sources and extent of buildup Explanation: Tailoring the scope based on contamination sources and severity ensures effective cleaning and resource allocation. Question 17. Which cleaning method is most suitable for removing particulate contamination from duct surfaces? A) Chemical sterilization B) Agitation combined with HEPA vacuuming C) Steam cleaning with high pressure D) Applying sealants without cleaning Answer: B) Agitation combined with HEPA vacuuming Explanation: Agitation loosens debris, which is then effectively captured by HEPA vacuuming, removing particulate contamination. Question 18. What is a common indicator that ductwork may require sealing or repair following inspection? A) Excessive noise during operation B) Visible leaks or gaps in duct joints C) Increased airflow D) High MERV ratings on filters Answer: B) Visible leaks or gaps in duct joints Explanation: Leaks can lead to contamination infiltration and reduced efficiency, indicating the need for sealing or repair. Question 19. During post-cleaning verification, which method is commonly used to confirm cleanliness? A) Visual inspection only B) NADCA Vacuum Test or equivalent surface cleanliness assessment C) Running the system at maximum speed D) Replacing filters without inspection Answer: B) NADCA Vacuum Test or equivalent surface cleanliness assessment Explanation: The NADCA Vacuum Test measures residual dust and debris, confirming that cleaning meets industry standards. Question 20. Which potential health effect is most associated with prolonged exposure to mold- contaminated HVAC systems? A) Skin burns B) Respiratory infections and allergic reactions C) Hearing loss D) Vision impairment Answer: B) Respiratory infections and allergic reactions Explanation: Mold exposure can cause respiratory issues, allergic reactions, and exacerbate asthma symptoms. Question 21. What is the primary purpose of using antimicrobial coatings on HVAC components? A) To improve airflow B) To inhibit microbial growth on surfaces C) To seal duct leaks D) To increase thermal insulation
Answer: B) To inhibit microbial growth on surfaces Explanation: Antimicrobial coatings prevent or slow microbial growth, reducing contamination and improving IAQ. Question 22. Which factor most influences the selection of cleaning products for HVAC system restoration? A) The color of the product B) Compatibility with system materials and effectiveness against specific contaminants C) Cost only D) The brand popularity Answer: B) Compatibility with system materials and effectiveness against specific contaminants Explanation: Proper product selection ensures effective cleaning without damaging system components. Question 23. When inspecting a system with suspected microbial contamination, what is a critical sign indicating a need for further testing? A) Presence of dust only B) Fuzzy or black growth on surfaces and persistent odors C) Brightly colored duct surfaces D) No visible issues but system noise Answer: B) Fuzzy or black growth on surfaces and persistent odors Explanation: Such signs suggest microbial contamination requiring microbiological testing and targeted treatment. Question 24. Which of the following best describes the primary goal when developing a project assessment for HVAC cleaning? A) To estimate the cost of repairs only B) To identify contamination sources, assess severity, and plan appropriate cleaning procedures C) To determine the age of the HVAC system D) To select the brand of filters to be used Answer: B) To identify contamination sources, assess severity, and plan appropriate cleaning procedures Explanation: A thorough assessment guides effective cleaning strategies and resource allocation. Question 25. Which of the following is an example of an engineering control used during HVAC cleaning? A) Wearing protective gloves B) Establishing negative pressure containment C) Using personal air purifiers D) Applying chemical biocides directly to ducts Answer: B) Establishing negative pressure containment Explanation: Negative pressure containment prevents contaminated dust and debris from escaping the work zone during cleaning. Question 26. What is a common sign that duct insulation may be contaminated? A) Excessive noise B) Visible mold or staining on insulation surfaces C) Increased airflow rate D) Cooler air temperature Answer: B) Visible mold or staining on insulation surfaces
Answer: B) Applying a chemical biocide after cleaning Explanation: Biocides are used post-cleaning to eradicate microbial contamination on duct surfaces. Question 32. During a system inspection, what does the presence of excessive noise from fans typically indicate? A) Proper operation B) Mechanical issues such as bearing wear or imbalance C) Complete cleaning has been performed D) The system is underpowered Answer: B) Mechanical issues such as bearing wear or imbalance Explanation: Excessive noise often signifies mechanical problems that may require maintenance or repair. Question 33. What is the main advantage of using a NADCA (National Air Duct Cleaners Association) standardized cleaning process? A) It guarantees zero microbial contamination. B) It ensures the cleaning meets industry quality standards and improves IAQ. C) It reduces cleaning costs to zero. D) It eliminates the need for post-cleaning inspection. Answer: B) It ensures the cleaning meets industry quality standards and improves IAQ. Explanation: NADCA standards provide best practices, ensuring effective cleaning and safety. Question 34. Which of the following is a key consideration when selecting access points for duct cleaning? A) The color of the ductwork B) The location of contamination and ease of access for cleaning tools C) The age of the building D) The system’s electrical components only Answer: B) The location of contamination and ease of access for cleaning tools Explanation: Proper access points facilitate comprehensive cleaning of contaminated areas. Question 35. How does moisture intrusion influence microbial contamination in HVAC systems? A) It inhibits microbial growth B) It creates a conducive environment for microbial proliferation C) It has no effect D) It only affects mechanical parts, not microbes Answer: B) It creates a conducive environment for microbial proliferation Explanation: Moisture provides the necessary environment for mold, bacteria, and fungi to grow. Question 36. Which component is most critical to inspect for contamination when evaluating the source of persistent odors? A) Thermostat sensor B) Cooling coils and drain pans C) External wall vents D) Electrical wiring connectors Answer: B) Cooling coils and drain pans Explanation: Dirty or microbial-laden coils and drain pans are common sources of odors within HVAC systems.
Question 37. When performing a visual inspection, what indicates that ductwork may have been previously contaminated and inadequately cleaned? A) Bright metallic surfaces B) Stains, streaks, or microbial growth signs C) Smooth duct interior surfaces D) No visible debris or staining Answer: B) Stains, streaks, or microbial growth signs Explanation: These signs suggest prior contamination and potential incomplete cleaning. Question 38. Which of the following statements best describes the role of a thorough pre-cleaning inspection? A) It replaces the need for post-cleaning verification B) It helps identify contamination sources, plan cleaning procedures, and estimate resources needed C) It is only necessary for new systems D) It is optional and not recommended Answer: B) It helps identify contamination sources, plan cleaning procedures, and estimate resources needed Explanation: Pre-cleaning inspection informs the scope, methods, and planning for effective cleaning. Question 39. Which factor most significantly affects the energy savings achieved through HVAC system cleaning? A) The color of the ductwork B) The degree of dirt and debris buildup on coils and fans C) The number of vents in the building D) The brand of the HVAC equipment Answer: B) The degree of dirt and debris buildup on coils and fans Explanation: Clean components operate more efficiently, reducing energy consumption. Question 40. What is a typical sign that ductwork needs to be sealed or repaired? A) Excessive system airflow B) Visible gaps, leaks, or disconnected joints C) Decrease in indoor humidity D) Increased filter lifespan Answer: B) Visible gaps, leaks, or disconnected joints Explanation: Leaks compromise system efficiency and indoor air quality, indicating the need for sealing or repairs. Question 41. Which component of an HVAC system is most prone to contamination from human activity and dust deposition? A) Thermostat B) Diffusers and supply registers C) External refrigerant lines D) Electrical panels Answer: B) Diffusers and supply registers Explanation: These are accessible points where dust and debris can settle and accumulate, leading to contamination. Question 42. Which contaminant size category is most concerning in terms of deep lung penetration and health effects?
C) The size of the building only D) The brand of the HVAC system Answer: B) The order that prevents re-contamination and optimizes cleaning efficiency Explanation: Proper sequence—typically starting from the furthest points and working toward the exhaust—ensures thorough cleaning. Question 48. Which microbial contaminant is most commonly associated with black, fuzzy growth in HVAC systems? A) Aspergillus mold B) Legionella bacteria C) Staphylococcus bacteria D) Influenza virus Answer: A) Aspergillus mold Explanation: Aspergillus is a common mold that appears as fuzzy, black or green patches, often found in damp HVAC environments. Question 49. When assessing a system with persistent odors, which component should be prioritized for inspection? A) Thermostat wiring B) Cooling coils and drain pans C) External vents only D) Electrical fuse box Answer: B) Cooling coils and drain pans Explanation: These components can harbor microbial growth or debris that produce odor. Question 50. Which of the following best describes the importance of documentation during HVAC inspection and cleaning? A) It is optional and not necessary. B) It provides evidence of work performed, issues found, and verification of cleanliness. C) It delays the process unnecessarily. D) It is only required for legal reasons and not for quality control. Answer: B) It provides evidence of work performed, issues found, and verification of cleanliness. Explanation: Proper documentation ensures accountability, quality assurance, and aids in future maintenance. Question 51. Which type of HVAC system is best suited for variable airflow needs across different zones? A) Constant volume system B) Variable Air Volume (VAV) system C) Hydronic system D) Dual duct system Answer: B) Variable Air Volume (VAV) system Explanation: VAV systems adjust airflow to different zones based on demand, providing flexibility and energy efficiency. Question 52. Which component is primarily responsible for removing moisture from the air in an HVAC system? A) Cooling coil
B) Humidifier C) Dehumidifier or cooling coil with condensate drain D) Air filter Answer: C) Dehumidifier or cooling coil with condensate drain Explanation: Dehumidification occurs when air passes over cooled coils, causing moisture to condense and drain away. Question 53. What is the typical MERV rating range for filters used in residential HVAC systems intended to remove airborne particles like dust and pollen? A) 1- 4 B) 5- 8 C) 9- 12 D) 13- 16 Answer: C) 9- 12 Explanation: MERV ratings of 9-12 are common in residential systems, effectively capturing dust, pollen, and mold spores. Question 54. During inspection, a technician notices that the duct insulation is damp and moldy. What should be the immediate action? A) Remove and replace the insulation, and address moisture source B) Cover it with a new layer of insulation C) Continue with cleaning without addressing moisture D) Seal the moldy areas with paint Answer: A) Remove and replace the insulation, and address moisture source Explanation: Moisture and mold in insulation pose health risks; removing and fixing the moisture source is essential. Question 55. Which biological agent is most likely to cause sick building syndrome symptoms when present in HVAC systems? A) Pollen B) Mold spores and bacteria C) Ozone D) Carbon monoxide Answer: B) Mold spores and bacteria Explanation: Biological contaminants like mold and bacteria can cause respiratory issues and contribute to sick building syndrome. Question 56. How does high-efficiency particulate air (HEPA) filtration benefit HVAC systems during cleaning? A) It increases airflow resistance without benefits B) It captures very small particles, improving IAQ and reducing microbial load C) It replaces the need for duct cleaning D) It prevents system overheating Answer: B) It captures very small particles, improving IAQ and reducing microbial load Explanation: HEPA filters effectively remove microscopic particles, including microbes, enhancing indoor air quality. Question 57. Which component of an HVAC system often acts as a primary site for dust and microbial buildup? A) Thermostat
Question 63. Which of the following is a common source of outdoor particulate matter entering HVAC systems? A) Pollen and dust from outdoor air B) Microbial biofilms C) Chemical off-gassing D) Microorganisms from indoor activities Answer: A) Pollen and dust from outdoor air Explanation: Outdoor particulates are carried into the system via ventilation air intake. Question 64. What is the primary health concern associated with inhalation of pet dander in indoor environments? A) Skin irritation B) Allergic reactions and asthma exacerbation C) Hearing loss D) Vision impairment Answer: B) Allergic reactions and asthma exacerbation Explanation: Pet dander contains allergens that can trigger respiratory allergies and asthma symptoms. Question 65. Which component is most likely to be affected by microbial contamination in a humid environment? A) Thermostat B) Cooling coils and drain pans C) Electrical panels D) External vents Answer: B) Cooling coils and drain pans Explanation: Moisture in humid environments promotes microbial growth on coils and in drain pans. Question 66. How does the use of chemical biocides contribute to HVAC system maintenance? A) They sterilize the entire building B) They inhibit microbial growth on cleaned surfaces C) They replace filters D) They increase airflow resistance Answer: B) They inhibit microbial growth on cleaned surfaces Explanation: Biocides are applied after cleaning to prevent microbial proliferation on surfaces. Question 67. Which of the following best describes the role of a plenum in an HVAC system? A) To supply outdoor air B) To distribute conditioned air to various zones C) To exhaust stale indoor air D) To filter incoming air Answer: B) To distribute conditioned air to various zones Explanation: The plenum acts as a distribution chamber for supply or return air. Question 68. When inspecting for contamination, what sign indicates a need for duct repair or sealing? A) Excessive airflow B) Visible leaks or disconnected joints C) Low noise levels D) High filter MERV rating
Answer: B) Visible leaks or disconnected joints Explanation: Leaks allow contaminants to enter and reduce efficiency, necessitating repair. Question 69. Which is most critical when developing a cleaning scope for a hospital HVAC system? A) The aesthetic appearance of ducts B) Specific infection control protocols and sterilization standards C) The number of vents only D) The brand of the HVAC equipment Answer: B) Specific infection control protocols and sterilization standards Explanation: Hospitals require rigorous standards to prevent infection transmission. Question 70. Which component typically requires regular inspection and cleaning to prevent microbial contamination? A) Thermostat B) Cooling coils and drain pans C) External casing D) Electrical wiring Answer: B) Cooling coils and drain pans Explanation: These components are moist and prone to microbial growth; regular cleaning prevents contamination. Question 71. How does microbial contamination in duct systems primarily impact indoor air quality? A) It improves air freshness B) It releases microbial spores and bioaerosols that can cause health issues C) It has no impact D) It reduces humidity levels Answer: B) It releases microbial spores and bioaerosols that can cause health issues Explanation: Contaminants like mold spores can become airborne and affect occupant health. Question 72. Which of the following is an effective method for verifying the cleanliness of an HVAC system after cleaning? A) Visual inspection only B) NADCA Vacuum Test or equivalent C) Running the system at maximum capacity D) Replacing all filters without inspection Answer: B) NADCA Vacuum Test or equivalent Explanation: The NADCA Vacuum Test provides an objective measure of residual debris and cleanliness. Question 73. What is the primary benefit of implementing containment controls during HVAC cleaning? A) To protect workers from electrical hazards B) To prevent cross-contamination of other building areas with dust and debris C) To accelerate the cleaning process arbitrarily D) To enhance airflow Answer: B) To prevent cross-contamination of other building areas with dust and debris Explanation: Proper containment prevents spreading contaminants during cleaning. Question 74. Which type of microbial growth appears as fuzzy or cottony patches on duct surfaces? A) Bacteria only
Answer: B) Cancer and respiratory issues Explanation: Prolonged VOC exposure can lead to serious health conditions, including cancer. Question 80. When performing a duct cleaning, what is the recommended sequence? A) Start from the supply side, then return, then exhaust B) Start with the most accessible areas, then proceed to the most contaminated ones C) Clean exhaust before supply and return ducts D) Randomly clean any component Answer: B) Start with the most accessible areas, then proceed to the most contaminated ones Explanation: A systematic approach ensures effective removal of contaminants without cross- contamination. Question 81. Which of the following is a sign that microbial contamination may be present in the HVAC system? A) Bright, clean duct surfaces B) Musty smell and visible mold growth C) Excessively high airflow D) Lack of any odors or stains Answer: B) Musty smell and visible mold growth Explanation: Musty odors and mold indicate microbial contamination requiring remediation. Question 82. Which component plays a key role in preventing microbial growth by removing moisture in an HVAC system? A) Air filter B) Condensate drain line and pan C) Thermostat D) External grille Answer: B) Condensate drain line and pan Explanation: Proper drainage of condensate prevents moisture accumulation that fosters microbial growth. Question 83. What is a critical factor influencing the effectiveness of duct cleaning? A) The age of the building B) Proper containment, equipment, and technique application C) The color of the duct material D) The size of the HVAC system only Answer: B) Proper containment, equipment, and technique application Explanation: Effective cleaning depends on correct procedures and equipment use to remove contaminants thoroughly. Question 84. Which microbial agent is most commonly associated with waterborne health risks in HVAC systems? A) Aspergillus mold B) Legionella bacteria C) Staphylococcus bacteria D) Influenza virus Answer: B) Legionella bacteria Explanation: Legionella proliferates in water systems like cooling towers and condensate pans, posing health risks.
Question 85. Which inspection tool is best suited for detecting pressure differentials indicating leaks or blockages? A) Borescope B) Manometer C) Thermometer D) Anemometer Answer: B) Manometer Explanation: A manometer measures pressure differences to identify leaks or obstructions in ductwork. Question 86. Which is an important aspect of managing customer expectations regarding odors after HVAC cleaning? A) Assure that all odors will be eliminated completely B) Explain that some odors may persist due to prior contamination or residual staining C) Avoid discussing odors altogether D) Claim that odors are unrelated to HVAC cleanliness Answer: B) Explain that some odors may persist due to prior contamination or residual staining Explanation: Setting realistic expectations helps maintain customer satisfaction. Question 87. Which component is most often responsible for distributing conditioned air to individual rooms? A) VAV box B) Diffuser or grille C) Return duct D) Exhaust fan Answer: B) Diffuser or grille Explanation: Diffusers and grilles deliver conditioned air into specific rooms or zones. Question 88. Why is moisture control critical during HVAC cleaning in humid climates? A) To accelerate microbial growth B) To prevent microbial contamination and mold growth C) To increase system energy consumption D) To improve airflow resistance Answer: B) To prevent microbial contamination and mold growth Explanation: Excess moisture promotes microbial proliferation, so controlling humidity is essential. Question 89. Which HVAC system component is most vulnerable to contamination from pests like rodents or insects? A) Thermostat B) Ductwork and filters C) External casing D) Electrical panels Answer: B) Ductwork and filters Explanation: Ducts and filters can be entry points and nesting sites for pests, leading to contamination. Question 90. Which cleaning method is most appropriate for removing debris from internal duct surfaces? A) Chemical sterilization only B) Mechanical agitation and HEPA vacuuming
A) Clean filters B) Dirty coils and restricted airflow C) Properly sealed ductwork D) High-quality insulation Answer: B) Dirty coils and restricted airflow Explanation: Contaminated coils reduce heat transfer efficiency, causing the system to work harder and consume more energy. Question 97. Which component is most critical to inspect for contamination when diagnosing persistent odors? A) Thermostat wiring B) Cooling coils and drain pans C) External vents D) Electrical fuse box Answer: B) Cooling coils and drain pans Explanation: These components can harbor microbial growth and debris that produce odors. Question 98. What is the primary health concern related to exposure to biological contaminants in HVAC systems? A) Skin irritation only B) Respiratory issues and allergic reactions C) Hearing loss D) Eye damage Answer: B) Respiratory issues and allergic reactions Explanation: Biological contaminants like mold spores can cause respiratory problems and allergies. Question 99. Which system component is most likely to be affected by contamination from chemical off-gassing? A) Thermostat B) Insulation and internal surfaces of ducts C) External casing only D) Electrical wiring Answer: B) Insulation and internal surfaces of ducts Explanation: Off-gassing materials can deposit chemicals on internal surfaces, affecting IAQ. Question 100. Which method is most effective for removing microbial biofilms from HVAC system surfaces? A) Mechanical scrubbing combined with chemical biocides B) Applying paint over affected areas C) High-pressure water jetting only D) Using only chemical disinfectants without cleaning Answer: A) Mechanical scrubbing combined with chemical biocides Explanation: Mechanical removal exposes biofilms for biocide action, ensuring microbial eradication. Question 101. Why is regular inspection of ductwork important in HVAC maintenance? A) To verify aesthetic appeal only B) To identify contamination, damage, and leaks early C) To increase system noise D) To prevent the need for filters
Answer: B) To identify contamination, damage, and leaks early Explanation: Early detection reduces long-term costs and maintains system efficiency and air quality. Question 102. Which of the following signs indicates that an HVAC system is producing inadequate airflow? A) Excessive noise B) Reduced air volume at diffusers and uneven temperatures C) Increased energy efficiency D) Bright, shiny duct surfaces Answer: B) Reduced air volume at diffusers and uneven temperatures Explanation: These signs point to blockages, leaks, or contamination restricting airflow. Question 103. What is the primary reason for sealing duct leaks after cleaning? A) To improve system performance and prevent contaminant infiltration B) To increase energy consumption C) To make the system more noisy D) To reduce airflow resistance intentionally Answer: A) To improve system performance and prevent contaminant infiltration Explanation: Sealing leaks maintains proper airflow and prevents outdoor contaminants from entering. Question 104. Which of the following best describes the role of a ventilation system in controlling indoor microbial contamination? A) To circulate contaminated air B) To dilute and remove airborne microbes and bioaerosols C) To increase humidity levels D) To trap microbes without removal Answer: B) To dilute and remove airborne microbes and bioaerosols Explanation: Proper ventilation reduces microbial concentrations in indoor air. Question 105. Which of the following is a common source of chemical contamination in HVAC systems? A) Outdoor dust B) Off-gassing from new building materials or cleaning agents C) Microbial growth on coils D) Moisture in duct insulation Answer: B) Off-gassing from new building materials or cleaning agents Explanation: Certain materials and cleaning chemicals release VOCs, contributing to chemical contamination. Question 106. During inspection, what indicates that ductwork may have been previously contaminated and inadequately cleaned? A) Bright, smooth interior surfaces B) Stains, streaks, or microbial growth signs C) Clear airflow with no odors D) Metallic duct surfaces only Answer: B) Stains, streaks, or microbial growth signs Explanation: Such signs suggest prior contamination or incomplete cleaning.
