Clean area classification MCQs With Answer are essential study tools for B. Pharm students preparing for exams and practicals in pharmaceutical microbiology and GMP. This concise, SEO-friendly introduction covers cleanroom terminology, ISO cleanroom classes, EU GMP grades, particle and viable monitoring, HEPA filtration, pressure cascades, laminar vs turbulent airflow, and environmental monitoring principles. Each MCQ includes clear options and precise answers to reinforce core concepts used in sterile production, validation, and quality control. Designed to boost retention and practical understanding, these questions help bridge theory with real-world clean area operation and compliance. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. What is the primary basis for clean area classification in pharmaceutical manufacturing?
- Microbial limits only
- Airborne particle concentration
- Chemical contamination levels
- Surface residue measurements
Correct Answer: Airborne particle concentration
Q2. Which international standard specifies airborne particle concentration limits for cleanrooms?
- USP 797
- EU GMP Annex 1
- ISO 14644-1
- ASTM E2096
Correct Answer: ISO 14644-1
Q3. Which ISO cleanroom class is approximately equivalent to the old FED-STD-209E class 100?
- ISO 3
- ISO 5
- ISO 7
- ISO 9
Correct Answer: ISO 5
Q4. What is the maximum allowable number of particles ≥0.5 µm per m3 for ISO 5?
- 3,520 particles/m3
- 35,200 particles/m3
- 352,000 particles/m3
- 3,520,000 particles/m3
Correct Answer: 3,520 particles/m3
Q5. In EU GMP grading, which grade represents the highest cleanliness for aseptic processing?
- Grade D
- Grade C
- Grade B
- Grade A
Correct Answer: Grade A
Q6. For aseptic filling operations, which EU GMP grade is typically used as the background zone to Grade A?
- Grade C
- Grade B
- Grade D
- Grade A
Correct Answer: Grade B
Q7. HEPA filters are specified by their efficiency at which particle size (commonly used)?
- 0.1 µm
- 0.3 µm
- 1.0 µm
- 5.0 µm
Correct Answer: 0.3 µm
Q8. Which airflow describes laminar flow in a cleanroom?
- Unidirectional, parallel airflow streams
- Random eddies and mixing flows
- High turbulence to dilute contaminants
- Recirculating low-velocity flow
Correct Answer: Unidirectional, parallel airflow streams
Q9. What is the typical recommended pressure differential between adjacent cleanrooms to reduce contamination risk?
- 1–2 Pa
- 3–5 Pa
- 10–15 Pa
- 30–40 Pa
Correct Answer: 10–15 Pa
Q10. What defines a viable particle in environmental monitoring?
- A particle composed of inert dust
- A living microorganism capable of growth
- A droplet of water
- An air molecule cluster
Correct Answer: A living microorganism capable of growth
Q11. Which active air monitoring technique directly collects viable airborne microorganisms onto agar?
- Optical particle counting
- Impaction air sampler
- Smoke visualization
- Differential pressure gauge
Correct Answer: Impaction air sampler
Q12. Passive monitoring using settle plates is primarily designed to detect what?
- Real-time particle counts
- Non-viable particle size distribution
- Viable microorganisms settling from the air
- Airflow velocity
Correct Answer: Viable microorganisms settling from the air
Q13. What does a cleanroom recovery test determine?
- The immediate microbial load in surfaces
- Time required for particle concentration to return to baseline after disturbance
- HEPA filter efficiency under load
- Maximum allowed humidity
Correct Answer: Time required for particle concentration to return to baseline after disturbance
Q14. ISO 14644-2 primarily covers which aspect of cleanrooms?
- Manufacturing practices
- Testing and monitoring to prove compliance
- Chemical contamination limits
- Pharmaceutical product specifications
Correct Answer: Testing and monitoring to prove compliance
Q15. In pharmaceutical terms, a “critical zone” refers to which area?
- Non-production corridor
- Area where the product is directly exposed to the environment
- Office space near production
- Storage area for packaging materials
Correct Answer: Area where the product is directly exposed to the environment
Q16. Why is personnel gowning essential in clean areas?
- To increase worker comfort
- To minimize particle shedding and microbial contamination
- To identify employee rank
- To reduce energy consumption
Correct Answer: To minimize particle shedding and microbial contamination
Q17. In environmental monitoring, what is the difference between an alert limit and an action limit?
- An alert requires immediate shutdown, action requires documentation
- An alert triggers investigation, action requires corrective measures
- An alert is higher than action
- They are interchangeable terms
Correct Answer: An alert triggers investigation, action requires corrective measures
Q18. Which device is best for visually checking airflow patterns in a cleanroom?
- Particle counter
- Smoke generator
- Settle plate
- Thermometer
Correct Answer: Smoke generator
Q19. How often should critical clean areas normally be re-certified under standard practice?
- Daily
- Monthly
- Annually or after major changes
- Every five years regardless of changes
Correct Answer: Annually or after major changes
Q20. What does a particle counter measure?
- Viable colony forming units (CFU)
- Non-viable airborne particle counts and sizes
- Surface residue concentrations
- Relative humidity only
Correct Answer: Non-viable airborne particle counts and sizes
Q21. Which of the following disinfectants is commonly used for routine surface disinfection in clean areas?
- 70% isopropyl alcohol
- Diluted household bleach without validation
- Pure water
- Lemon juice
Correct Answer: 70% isopropyl alcohol
Q22. What particle size is most commonly used as a reference for cleanroom monitoring in pharmaceutical manufacturing?
- 0.1 µm
- 0.5 µm
- 2.5 µm
- 10 µm
Correct Answer: 0.5 µm
Q23. A HEPA filter labeled 99.97% efficient removes what fraction of particles at the rated size?
- 99.97% of particles at 0.3 µm
- 100% of all particles
- Only particles larger than 10 µm
- 50% of particles at 0.3 µm
Correct Answer: 99.97% of particles at 0.3 µm
Q24. Which of the following is a non-viable monitoring method?
- Settle plate monitoring
- Surface contact plates
- Optical particle counting
- Air impaction sampling onto agar
Correct Answer: Optical particle counting
Q25. What unit is commonly used to report viable air monitoring results from active sampling?
- Particles per m3
- CFU per m3
- mg/m3
- ppm
Correct Answer: CFU per m3
Q26. Which parameter is essential to monitor in addition to particles and microbes to maintain product stability?
- Room color
- Temperature and relative humidity
- Ambient light intensity only
- Noise level
Correct Answer: Temperature and relative humidity
Q27. Which method is typically used for HEPA filter integrity testing during certification?
- Visual inspection only
- PAO/DOP aerosol challenge and downstream scanning
- Settle plate monitoring
- Pressure differential alone
Correct Answer: PAO/DOP aerosol challenge and downstream scanning
Q28. Which statement about laminar flow hoods is false?
- They provide unidirectional airflow to sweep contaminants away
- They eliminate all contamination risk regardless of technique
- HEPA-filtered air is supplied directly to the workspace
- They are commonly used for aseptic manipulations
Correct Answer: They eliminate all contamination risk regardless of technique
Q29. Which monitoring approach provides near real-time indication of non-viable contamination?
- Surface contact plate incubation
- Active air impaction onto agar
- Continuous particle counting
- Settle plate exposure
Correct Answer: Continuous particle counting
Q30. For sterile compounding in Grade A zones, which is typically required for gloves?
- Non-sterile gloves are sufficient
- Sterile gloves used and changed frequently
- Gloves are optional if gowns are worn
- Only single glove on dominant hand
Correct Answer: Sterile gloves used and changed frequently
Q31. What is meant by “cleanroom recovery time”?
- Time the room is unoccupied
- Time to reach specified particle level after a disturbance
- Time to change HEPA filters
- Time between cleaning cycles
Correct Answer: Time to reach specified particle level after a disturbance
Q32. Which statement is true regarding ISO cleanroom classes?
- A higher ISO class number indicates a cleaner room
- A lower ISO class number indicates a cleaner room
- ISO numbers are unrelated to cleanliness
- ISO 9 is cleaner than ISO 5
Correct Answer: A lower ISO class number indicates a cleaner room
Q33. What is the primary purpose of a pressure cascade in a pharmaceutical facility?
- To control temperature gradients
- To maintain relative humidity only
- To prevent ingress of contaminants by directing airflow from cleaner to less clean areas
- To improve lighting efficiency
Correct Answer: To prevent ingress of contaminants by directing airflow from cleaner to less clean areas
Q34. Which source contributes the most to particle and microbial contamination in a cleanroom?
- HVAC equipment
- Personnel
- Lighting fixtures
- Building structure only
Correct Answer: Personnel
Q35. What is the common purpose of a Restricted Access Barrier System (RABS)?
- To provide complete physical isolation like an isolator
- To provide a partial physical barrier to reduce operator interaction with the process
- To replace HVAC systems
- To provide storage for raw materials
Correct Answer: To provide a partial physical barrier to reduce operator interaction with the process
Q36. Which instrument is used to measure airflow velocity in supply ducts or clean zones?
- Photometer
- Anemometer
- Colony counter
- Manometer only
Correct Answer: Anemometer
Q37. What is a primary consideration when selecting a disinfectant for clean area use?
- Color of the disinfectant
- Proven efficacy against relevant microorganisms and material compatibility
- Price as the sole factor
- Scent and fragrance
Correct Answer: Proven efficacy against relevant microorganisms and material compatibility
Q38. During cleanroom certification, which test assesses the HEPA filter for leaks?
- Air change rate measurement
- Downstream leak scan using challenge aerosol
- Surface swab for microbes
- Settle plate exposure
Correct Answer: Downstream leak scan using challenge aerosol
Q39. Which practice helps prevent cross-contamination between adjacent clean areas?
- Random door opening during production
- Implementing pressure cascades and controlled entry procedures
- Sharing equipment without cleaning
- Allowing external materials inside without quarantine
Correct Answer: Implementing pressure cascades and controlled entry procedures
Q40. What is the usual objective of environmental monitoring programs in pharmaceutical cleanrooms?
- To eliminate the need for cleaning
- To provide data demonstrating control of microbiological and particle contamination
- To increase production speed regardless of contamination
- To certify personnel skills only
Correct Answer: To provide data demonstrating control of microbiological and particle contamination
Q41. Which method is best to detect transient peaks of non-viable particles during operations?
- Periodic settle plate exposure
- Continuous particle monitoring with alarms
- Weekly surface swabs
- Visual inspection alone
Correct Answer: Continuous particle monitoring with alarms
Q42. Which area should be cleaned and disinfected most frequently in a sterile manufacturing suite?
- Office area
- Grade A critical zone
- Corridor outside the suite
- Storage room for packaging
Correct Answer: Grade A critical zone
Q43. Which particle size is most often associated with respirable aerosols that can remain airborne for long periods?
- >10 µm
- 5–10 µm
- <1–5 µm range
- >50 µm
Correct Answer: <1–5 µm range
Q44. What is the role of a duct-mounted HEPA filter in a cleanroom HVAC system?
- To increase room humidity
- To remove fine particles from supply air before it enters the clean area
- To provide lighting control
- To cool the manufacturing equipment
Correct Answer: To remove fine particles from supply air before it enters the clean area
Q45. Which ISO class allows the highest concentration of particles and is therefore the least clean?
- ISO 3
- ISO 5
- ISO 7
- ISO 9
Correct Answer: ISO 9
Q46. Smoke studies performed during validation primarily evaluate what?
- Microbial levels on surfaces
- Airflow patterns and directionality
- Chemical residues
- HEPA filter efficiency numerically
Correct Answer: Airflow patterns and directionality
Q47. Which of the following best describes an isolator used in aseptic processing?
- A completely open workbench
- A closed, controlled environment providing a physical barrier between operator and product
- A simple hood without filtration
- An unfiltered storage cabinet
Correct Answer: A closed, controlled environment providing a physical barrier between operator and product
Q48. What is the most appropriate immediate action when a particle alarm in an ISO 5 zone exceeds the action limit during critical operations?
- Ignore the alarm and continue
- Stop operations, investigate cause, and take corrective actions
- Decrease air changes to compensate
- Open doors to equalize pressure
Correct Answer: Stop operations, investigate cause, and take corrective actions
Q49. Which size threshold is commonly used by ISO 14644-1 standards for reporting default particle concentrations for classification?
- 0.05 µm
- 0.5 µm
- 5 µm
- 50 µm
Correct Answer: 0.5 µm
Q50. After major maintenance to HVAC or layout changes in a clean area, what must be performed before resuming routine sterile operations?
- Only visual inspection
- Full re-certification and qualification including particle and airflow tests
- Informal verbal approval from a technician
- No action is required
Correct Answer: Full re-certification and qualification including particle and airflow tests
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