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Question 1. Which ISO 14644-1 class limits particles ≥ 0.5 μm to a maximum of 3 200 particles per cubic meter? A) Class 3 B) Class 5 C) Class 7 D) Class 9 Answer: B Explanation: ISO 14644-1 specifies that Class 5 allows up to 3 200 particles ≥ 0.5 μm per m³, whereas Class 3 is far stricter and Class 7 and 9 are less strict. Question 2. Under the legacy Federal Standard 209E, which class corresponds most closely to ISO 14644-1 Class 7? A) Class 10 B) Class 100 C) Class 1 000 D) Class 10 000 Answer: C Explanation: FS-209E Class 1 000 (10⁴ particles ≥ 0.5 μm per ft³) maps approximately to ISO 14644 - 1 Class 7. Question 3. In cleanroom occupancy states, which term describes the environment after construction but before any equipment is installed? A) As-built B) At-rest C) Operational D) Commissioned Answer: A
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Explanation: “As-built” refers to the cleanroom condition after construction and verification of design, prior to equipment installation. Question 4. Which EU guideline specifically addresses cleanroom requirements for sterile medicinal products? A) EU GMP Annex 1 B) EU GMP Annex 4 C) EU GMP Annex 15 D) EU GMP Annex 17 Answer: A Explanation: EU GMP Annex 1 sets the standards for sterile manufacturing, including cleanroom classifications and monitoring. Question 5. USP <797> primarily governs which type of cleanroom environment? A) Radiopharmacy B) Compounding sterile preparations C) Hazardous drug handling D) Non-sterile compounding Answer: B Explanation: USP <797> provides guidelines for sterile compounding, requiring appropriate cleanroom classes and environmental monitoring. Question 6. For a Class 5 cleanroom, how many independent sampling points are required at a minimum according to ISO 14644-1? A) 1 B) 4 C) 9
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C) 0.5 in wg D) 1.0 in wg Answer: B Explanation: A minimum of 0.1 in wg (≈ 250 Pa) is recommended to prevent contaminant migration from the less clean to the cleaner area. Question 10. In a recovery time test, the “settling time” refers to: A) Time for the HVAC system to reach full flow after start-up B) Time required for particle concentration to drop to the class limit after a disturbance C) Time to calibrate the particle counter D) Time to achieve temperature setpoint Answer: B Explanation: Recovery time measures how quickly the environment returns to the specified cleanliness level after a contamination event. Question 11. Which filtration mechanism is dominant for particles < 0.1 μm? A) Interception B) Impaction C) Diffusion D) Electrostatic attraction Answer: C Explanation: Diffusion becomes the primary capture mechanism for ultrafine particles (<0.1 μm) due to Brownian motion. Question 12. A HEPA filter is rated to remove 99.97 % of particles at which most-penetrating particle size (MPPS)?
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A) 0.01 μm B) 0.1 μm C) 0.3 μm D) 1.0 μm Answer: C Explanation: The MPPS for HEPA filters is about 0.3 μm, where the filter’s efficiency is lowest; it still achieves 99.97 % removal at this size. Question 13. ULPA filters differ from HEPA filters primarily in: A) Media thickness B) Rated efficiency at 0.1 μm C) Frame material D) Required pressure drop Answer: B Explanation: ULPA filters must achieve ≥99.999 % efficiency at 0.1 μm, a stricter requirement than the HEPA standard of 99.97 % at 0.3 μm. Question 14. Which aerosol is most commonly used in in-situ HEPA filter leak testing in the United States? A) Polystyrene latex (PSL) B) Dioctyl phthalate (DOP) C) Polyalphaolefin (PAO) D) Sodium chloride (NaCl) Answer: C Explanation: PAO has largely replaced DOP in the U.S. due to toxicity concerns while providing similar particle size distribution.
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Explanation: At high concentrations, multiple particles may enter the sensing volume simultaneously, causing under-counting; for a 100 L/min DPC, this becomes significant around 10 000 particles/L. Question 18. When using a hot-wire anemometer to map velocity in a laminar flow hood, the primary source of measurement error is: A) Wire corrosion B) Temperature fluctuations of the surrounding air C) Vibration of the sensor D) Magnetic interference Answer: B Explanation: Hot-wire anemometers rely on cooling of the heated wire; ambient temperature changes directly affect the heat transfer and thus the velocity reading. Question 19. A digital micromanometer used to verify room pressure should be calibrated against: A) A calibrated flow hood B) A primary pressure standard (e.g., dead-weight tester) C) A calibrated temperature probe D) A calibrated particle counter Answer: B Explanation: Pressure instruments are traceable to primary pressure standards such as dead-weight testers to ensure accuracy. Question 20. The purpose of a balometer (flow hood) in cleanroom testing is to: A) Measure particle concentration at the filter face
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B) Determine total supply air volume at a diffuser or terminal filter C) Verify temperature uniformity across the room D) Detect electrostatic discharge on surfaces Answer: B Explanation: A balometer measures airflow rate (CFM) from a diffuser or filter, enabling verification of design air change rates. Question 21. Glycol-based smoke generators are preferred for airflow visualization because: A) Glycol particles are electrically charged B) They produce visible, neutrally buoyant particles that follow air streams closely C) Glycol is non-flammable and safe for all cleanrooms D) They generate particles larger than 10 μm, which are easy to see Answer: B Explanation: Glycol smoke creates sub-micron particles that are neutrally buoyant, accurately tracing airflow patterns without settling quickly. Question 22. In a mixed-flow cleanroom, the recommended maximum velocity at the diffuser face is: A) 0.1 m/s B) 0.3 m/s C) 0.6 m/s D) 1.0 m/s Answer: C Explanation: ISO 14644-1 suggests a maximum supply velocity of 0.6 m/s for mixed-flow rooms to avoid turbulence while maintaining adequate air mixing.
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Question 26. According to ISO 14644-4, the acceptable limit for a containment leak test using a calibrated particle counter is: A) 0 particles per minute B) ≤ 1 particle per minute above background C) ≤ 5 particles per minute above background D) ≤ 10 particles per minute above background Answer: C Explanation: ISO 14644-4 permits a maximum of 5 particles/min above background for a successful containment leak test. Question 27. The “95 % Upper Confidence Limit (UCL)” for a small sample size is used to: A) Determine the maximum allowable temperature variance B) Establish the worst-case particle concentration from limited data C) Calculate the required number of filter changes per year D) Set the pressure differential between zones Answer: B Explanation: The UCL provides a statistical boundary that, with 95 % confidence, the true mean does not exceed, useful for limited particle count samples. Question 28. Which of the following is the most significant source of particles generated by personnel in a cleanroom? A) Shoe soles B) Skin flakes C) Hair shedding D) Clothing fibers
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Answer: B Explanation: Human skin shedding contributes the majority of airborne particles from personnel, outpacing hair or clothing. Question 29. The recommended gowning sequence for a Class 5 cleanroom begins with: A) Gloves B) Coverall (full-body suit) C) Shoe covers D) Hair cover (bouffant) Answer: D Explanation: The proper donning order starts with head cover, then shoe covers, then gown, and finally gloves to avoid contaminating previously donned items. Question 30. Which cleaning agent is most appropriate for sporicidal disinfection of a sterile manufacturing cleanroom? A) 70 % Isopropyl alcohol B) 0.5 % Sodium hypochlorite C) 2 % Glutaraldehyde D) 0.05 % Quaternary ammonium Answer: C Explanation: Glutaraldehyde at 2 % provides sporicidal activity required for high-risk sterile environments. Question 31. Electrostatic discharge (ESD) control testing typically measures: A) Surface resistivity of work surfaces
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Question 34. During OQ (Operational Qualification), which parameter is typically NOT evaluated? A) Alarm setpoints for pressure differentials B) Filter media integrity after 5 years of service C) Temperature uniformity across the room D) Flow reversals on standby mode Answer: B Explanation: Filter media integrity over long periods is part of PQ (Performance Qualification) or periodic maintenance, not OQ. Question 35. A performance qualification (PQ) test for a cleanroom most commonly includes: A) Verification of HVAC control software version B) Long-term particle monitoring under normal production conditions C) Calibration of all pressure gauges D) Review of design drawings Answer: B Explanation: PQ validates that the cleanroom consistently meets class requirements during routine operation, often using extended particle monitoring. Question 36. Which data element is mandatory on a cleanroom validation report? A) Names of all operators present during testing B) Calibration certificates for all instruments used, with dates C) Supplier contact information for HVAC components D) Photographs of the cleanroom ceiling Answer: B
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Explanation: Calibration certificates ensure traceability and must be included to demonstrate instrument accuracy at the time of testing. Question 37. When an out-of-specification (OOS) result occurs during a containment leak test, the first corrective action should be: A) Re-run the test immediately without any changes B) Shut down the cleanroom and evacuate personnel C) Identify and isolate the suspected leak source, then retest D) Replace all HEPA filters in the zone Answer: C Explanation: OOS results require investigation; isolating the leak source and confirming the fix before retesting is the appropriate response. Question 38. NIST-traceable calibration ensures that an instrument’s measurements are: A) Within ± 5 % of the manufacturer’s specifications B) Directly linked to national standards for accuracy C) Approved for use in pharmaceutical cleanrooms only D) Automatically valid for ten years Answer: B Explanation: NIST traceability means the calibration chain leads back to national measurement standards, guaranteeing recognized accuracy. Question 39. The “make-up air” for a cleanroom must be filtered to at least: A) ISO Class 9 B) ISO Class 8 C) ISO Class 7
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Question 42. Which of the following is a common method for measuring filter pressure drop (ΔP) in situ? A) Using a manometer across the filter housing B) Measuring temperature before and after the filter C) Counting particles upstream and downstream of the filter D) Observing airflow velocity at the filter face Answer: A Explanation: A differential pressure gauge (manometer) directly measures ΔP across the filter, indicating filter loading and performance. Question 43. The “MPPS” (most penetrating particle size) for ULPA filters is typically: A) 0.01 μm B) 0.05 μm C) 0.1 μm D) 0.3 μm Answer: C Explanation: ULPA filters are most challenged at around 0.1 μm; they must still achieve ≥ 99.999 % efficiency at this size. Question 44. When performing a “particle count” survey, the sampling time per location is usually: A) 15 seconds B) 30 seconds C) 60 seconds D) 5 minutes Answer: C
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Explanation: ISO 14644-1 recommends a minimum of 60 seconds per sampling location to obtain statistically reliable counts. Question 45. Which statistical method is recommended for determining the required number of samples when validating a new cleanroom design? A) Six-sigma analysis B) Student’s t-test for small samples C) Poisson distribution confidence interval D) Linear regression of particle trends Answer: C Explanation: Particle counts follow a Poisson distribution; confidence intervals based on Poisson statistics determine sample size for validation. Question 46. A “dead-zone” in airflow visualization is best described as: A) An area with zero temperature gradient B) A region where airflow velocity is significantly lower than design values C) A zone with high humidity levels D) A space where pressure is higher than surrounding areas Answer: B Explanation: Dead-zones are stagnant regions with insufficient airflow, often identified using smoke or tracer gas. Question 47. The primary purpose of a “cleanroom gowning room” is to: A) Store cleanroom equipment B) Provide a controlled environment for donning cleanroom attire C) House the HVAC control panel D) Act as a de-contamination chamber for raw materials
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D) Guidelines for personnel training Answer: B Explanation: ISO 14644-3 specifies the test methods for monitoring and verifying cleanroom performance. Question 51. When a cleanroom’s temperature setpoint is 22 °C ± 2 °C, the acceptable temperature range is: A) 20 °C – 24 °C B) 21 °C – 23 °C C) 19 °C – 25 °C D) 22 °C – 26 °C Answer: A Explanation: ± 2 °C around 22 °C yields a range of 20 °C to 24 °C. Question 52. Which humidity range is most commonly required for a pharmaceutical sterile manufacturing cleanroom? A) 20 % – 30 % RH B) 30 % – 40 % RH C) 45 % – 55 % RH D) 60 % – 70 % RH Answer: C Explanation: 45 % – 55 % RH balances product stability and static control in sterile compounding environments. Question 53. The “particle counter”’s “size bin” of 0.3 μm – 0.5 μm is most relevant for which cleanliness class? A) Class 1 B) Class 5
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C) Class 7 D) Class 9 Answer: B Explanation: Class 5 limits are defined at the 0.3 μm size; counts in this bin directly affect compliance. Question 54. Which of the following is a primary advantage of using ULPA filters over HEPA filters in a critical-process area? A) Lower pressure drop B) Higher airflow rates C) Superior removal efficiency for sub-0.1 μm particles D) Reduced cost Answer: C Explanation: ULPA filters provide ≥ 99.999 % efficiency at 0.1 μm, offering better protection against ultrafine particles. Question 55. In a containment leak test using sulfur hexafluoride (SF₆) as tracer gas, detection is typically performed with: A) A photoionization detector (PID) B) A flame ionization detector (FID) C) An infrared gas analyzer D) A mass spectrometer Answer: C Explanation: SF₆ absorbs infrared radiation; an infrared gas analyzer quantifies its concentration for leak detection. Question 56. A “cleanroom certification” that includes IQ, OQ, and PQ is also known as:
