Air Filtration & Dust Collection MCQs With Answer

This quiz collection on “Air Filtration & Dust Collection MCQs With Answer” is designed specifically for M.Pharm students studying MIP 203T – Pharmaceutical Production Technology. It focuses on principles, equipment, testing methods, cleanroom practice, and regulatory expectations related to air filtration and dust control in pharmaceutical manufacturing. The questions explore filtration mechanisms, HEPA/ULPA performance, aerosol testing, dust collectors (cyclones, baghouses, scrubbers), filter integrity, contamination control strategies, and practical design considerations for sterile processing areas. Use these targeted MCQs to test conceptual understanding, prepare for exams, and reinforce best practices in air quality management for pharmaceutical production.

Q1. Which filtration mechanism predominates for removal of ultrafine particles below about 0.1 µm in fibrous filters?

• Inertial impaction
• Interception
• Diffusion
• Sieving

Correct Answer: Diffusion

Q2. What efficiency and particle size are commonly used to specify a HEPA filter in pharmaceutical cleanrooms?

• 95% at 5 µm
• 99.97% at 0.3 µm (most penetrating particle size)
• 85% at 0.1 µm
• 70% at 10 µm

Correct Answer: 99.97% at 0.3 µm (most penetrating particle size)

Q3. The “most penetrating particle size” (MPPS) for mechanical HEPA media typically falls in which range?

• 5–10 µm
• 1–2 µm
• 0.1–0.3 µm
• 0.001–0.01 µm

Correct Answer: 0.1–0.3 µm

Q4. The primary purpose of a DOP/PAO aerosol test on a HEPA filter is to:

• Measure pressure drop across the filter during normal operation
• Determine filter media thickness
• Detect leaks or integrity failures using an aerosol challenge
• Evaluate chemical compatibility with vapors

Correct Answer: Detect leaks or integrity failures using an aerosol challenge

Q5. A cyclone dust collector separates particles from an airstream primarily by which principle?

• Electrostatic attraction
• Centrifugal/inertial forces causing particles to impact walls
• Adsorption onto activated carbon
• Diffusion onto filter fibers

Correct Answer: Centrifugal/inertial forces causing particles to impact walls

Q6. Which cleaning method is most commonly used for pulse-jet baghouse dust collectors to dislodge accumulated cake?

• Reverse air flow with long-duration cycles
• Pulse-jet high-pressure short bursts of compressed air
• Mechanical shaking only
• Continuous wet washing

Correct Answer: Pulse-jet high-pressure short bursts of compressed air

Q7. Activated carbon filters are most effective for control of which type of contaminants in process air?

• Non-volatile particulates larger than 10 µm
• Biological spores and bacteria
• Gaseous organic vapors and odorous compounds
• Inert metal dusts

Correct Answer: Gaseous organic vapors and odorous compounds

Q8. According to common cleanroom classification mapping, ISO Class 5 is approximately equivalent to which EU GMP Grade?

• Grade D
• Grade C
• Grade B
• Grade A

Correct Answer: Grade A

Q9. A commonly recommended face velocity for terminal HEPA filters creating unidirectional (laminar) flow in aseptic workbenches is about:

• 0.15 m/s
• 0.45 m/s
• 1.5 m/s
• 3.0 m/s

Correct Answer: 0.45 m/s

Q10. Electrostatic precipitators remove fine particles from gas streams primarily by:

• Inertial impaction on curved surfaces
• Electrostatic charging of particles and collection on oppositely charged plates
• Adsorption onto porous media
• Coagulation in a wet scrubber liquid

Correct Answer: Electrostatic charging of particles and collection on oppositely charged plates

Q11. Which statement best describes the relationship between MERV ratings and HEPA filters?

• MERV 8 filters are equivalent to HEPA
• MERV 14 is identical in performance to HEPA
• MERV 16 equals HEPA performance
• No MERV rating fully equals HEPA; HEPA performance is beyond MERV 16

Correct Answer: No MERV rating fully equals HEPA; HEPA performance is beyond MERV 16

Q12. For containment between cleanroom zones, a recommended pressure differential often used to maintain airflow from cleaner to less-clean areas is approximately:

• 1–2 Pa
• 10–15 Pa
• 50–75 Pa
• 150–200 Pa

Correct Answer: 10–15 Pa

Q13. The respirable particle fraction most likely to reach the gas-exchange regions (alveoli) of the lung is typically considered to be particles smaller than about:

• 10 µm
• 5 µm
• 4 µm
• 0.1 µm

Correct Answer: 4 µm

Q14. Which challenge aerosol replaced DOP (dioctyl phthalate) in modern filter integrity testing because it is less hazardous and non-phthalate?

• Sodium chloride (NaCl)
• PAO (polyalphaolefin)
• Polystyrene latex spheres (PSL)
• Silica dust

Correct Answer: PAO (polyalphaolefin)

Q15. Which filter bank or pack design increases filter surface area while reducing face velocity and pressure drop, commonly used in HVAC prefiltering?

• Flat panel single filter
• V-bank or multi-pocket filter
• Cyclonic cartridge
• Perforated metal mesh

Correct Answer: V-bank or multi-pocket filter

Q16. The most common operational cause of measured bypass flow around a HEPA filter is:

• Excessive particle loading of the media
• Leaks due to improper gasketing or frame sealing
• High humidity condensing on the media
• Ageing of the HEPA glass fibers

Correct Answer: Leaks due to improper gasketing or frame sealing

Q17. Wet scrubbers are particularly advantageous for removing which combination from an exhaust stream?

• Large inert particles only
• Volatile organic gases only
• Both soluble gases/vapors and fine particulates via absorption and impaction
• Radioactive gases specifically

Correct Answer: Both soluble gases/vapors and fine particulates via absorption and impaction

Q18. In aseptic filling of parenteral products, the primary engineering control to minimize particulate contamination at the fill zone is:

• Activated carbon adsorption upstream
• Terminal HEPA filtration providing ISO 5 unidirectional flow at the fill zone
• Periodic manual cleaning with alcohol only
• Use of high-efficiency bag filters in the exhaust stack

Correct Answer: Terminal HEPA filtration providing ISO 5 unidirectional flow at the fill zone

Q19. As a HEPA filter loads with captured particles during operation, the common aerodynamic consequences are:

• Pressure drop decreases and airflow increases
• No change in pressure drop or airflow
• Pressure drop increases, typically causing higher fan energy use and reduced airflow if fan capacity is fixed
• Filter efficiency rapidly drops to zero

Correct Answer: Pressure drop increases, typically causing higher fan energy use and reduced airflow if fan capacity is fixed

Q20. After installation of a new HEPA filter, the most appropriate field integrity test to verify proper performance and absence of leaks is:

• Visual inspection of media color
• Bubble point test with water only
• Aerosol photometer challenge (PAO/DOP) with downstream scanning
• pH measurement of filter frame

Correct Answer: Aerosol photometer challenge (PAO/DOP) with downstream scanning

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