Air sampling and testing standards MCQs With Answer

Introduction: This quiz collection on Air sampling and testing standards is designed specifically for M.Pharm students studying Bioprocess Engineering and Technology. It covers fundamental principles, sampling methods (active and passive), commonly used instruments, standard references (ISO, USP, EU GMP Annex 1), and practical considerations such as sample volume, media selection, and interpretation of results. Questions focus on real-world monitoring of viable and non‑viable contaminants in controlled environments, critical for aseptic manufacturing and cleanroom qualification. Use these MCQs to test conceptual understanding and prepare for exams or practical lab work; explanations and references are recommended for deeper study after attempting each question.

Q1. What best distinguishes active air sampling from passive air sampling?

• Active sampling uses a pump or sampler to draw a defined volume of air through/onto a collection medium, whereas passive sampling relies on natural settling or diffusion.
• Active sampling only measures non‑viable particles, while passive sampling measures only viable organisms.
• Active sampling is qualitative, whereas passive sampling always gives quantitative counts per cubic metre.
• Active sampling is used only for surface monitoring, while passive sampling is used only for air monitoring.

Correct Answer: Active sampling uses a pump or sampler to draw a defined volume of air through/onto a collection medium, whereas passive sampling relies on natural settling or diffusion.

Q2. Which standard is primarily used for classification of cleanrooms by airborne particle concentrations?

• ISO 14644‑1
• ISO 14698
• USP <1116>
• ICH Q9

Correct Answer: ISO 14644‑1

Q3. Which document specifically addresses microbial monitoring of cleanrooms and controlled environments?

• ISO 14698
• ISO 14644‑1
• ISO 9001
• USP <795>

Correct Answer: ISO 14698

Q4. What is the standard unit used to report viable airborne microbial contamination?

• CFU/m3
• particles/cm3
• mg/m3
• CFU/cm2

Correct Answer: CFU/m3

Q5. Which sampler provides size‑fractionated viable counts by inertial impaction across multiple stages?

• Andersen six‑stage cascade impactor
• Optical particle counter
• Settle plate
• Surface contact plate

Correct Answer: Andersen six‑stage cascade impactor

Q6. Which of the following is an example of passive air sampling?

• Exposing open agar plates (settle plates) to the environment without forced air movement
• Using a slit‑to‑agar volumetric air sampler
• Passing air through a liquid impinger
• Active sampling with a centrifugal sampler

Correct Answer: Exposing open agar plates (settle plates) to the environment without forced air movement

Q7. What is the primary principle of impingement air sampling?

• Air is bubbled or drawn through a liquid medium where microorganisms are captured
• Particles settle by gravity onto an agar surface
• Particles are counted optically without regard to viability
• Air is passed over sticky adhesive strips for later microscopic examination

Correct Answer: Air is bubbled or drawn through a liquid medium where microorganisms are captured

Q8. What does the ‘positive‑hole correction’ apply to when using impactor samplers?

• Correcting colony counts because multiple particles can pass through the same inlet hole and lead to underestimation if uncorrected
• Adjusting counts for humidity effects on agar plates
• Compensating for sampler battery voltage fluctuations
• Normalizing counts to surface area for settle plates

Correct Answer: Correcting colony counts because multiple particles can pass through the same inlet hole and lead to underestimation if uncorrected

Q9. Why are neutralizing agents (e.g., lecithin, polysorbate 80) sometimes included in sampling media?

• To inactivate residual disinfectants or antimicrobials on surfaces and in air so organisms can be recovered
• To change the colour of the agar for easier colony counting
• To increase the flow rate of volumetric samplers
• To selectively inhibit fungi while promoting bacterial growth

Correct Answer: To inactivate residual disinfectants or antimicrobials on surfaces and in air so organisms can be recovered

Q10. What is the main difference between viable and non‑viable monitoring in cleanrooms?

• Viable monitoring detects living microorganisms (e.g., CFU), whereas non‑viable monitoring counts all particles irrespective of viability
• Viable monitoring uses lasers, while non‑viable monitoring uses culture media
• Viable monitoring is only done outdoors, non‑viable only indoors
• Viable monitoring reports in mg/m3, non‑viable in CFU/m3

Correct Answer: Viable monitoring detects living microorganisms (e.g., CFU), whereas non‑viable monitoring counts all particles irrespective of viability

Q11. Which incubation conditions are commonly used for environmental bacterial recovery from air samples?

• Approximately 30–35 °C for 48–72 hours
• 4 °C for 7 days
• 60 °C for 24 hours
• 10–15 °C for 2 weeks

Correct Answer: Approximately 30–35 °C for 48–72 hours

Q12. In many aseptic manufacturing monitoring plans, what is a commonly used single sample air volume for active viable sampling in critical locations?

• Typically 1 m3 (1000 L) per sample
• 10 mL per sample
• 100 m3 per sample
• 1 L per sample

Correct Answer: Typically 1 m3 (1000 L) per sample

Q13. How does a slit‑to‑agar (rotating) sampler operate?

• Air is drawn through a narrow slit and impacts directly onto a rotating agar plate, providing time‑resolved deposition
• Air is filtered onto a membrane that is then dissolved into broth
• Air is sampled into a liquid impinger and then plated
• Air particles are detected optically and converted to CFU by algorithm

Correct Answer: Air is drawn through a narrow slit and impacts directly onto a rotating agar plate, providing time‑resolved deposition

Q14. Which of the following factors generally does NOT significantly affect microbial recovery from an air sample?

• The colour of the sampler housing
• Relative humidity during sampling
• Sampling flow rate and sampler design
• Time between sampling and incubation

Correct Answer: The colour of the sampler housing

Q15. Alert and action limits for environmental monitoring are normally established based on what?

• Historical baseline data, qualification/validation studies, and risk assessment
• Random values taken from unrelated industries
• Theoretical particle models only, without empirical data
• Manufacturer’s advertising claims

Correct Answer: Historical baseline data, qualification/validation studies, and risk assessment

Q16. Which regulatory guidance provides specific requirements and expectations for environmental monitoring in aseptic manufacturing in the EU?

• EU GMP Annex 1 (sterile medicinal products)
• FDA 21 CFR Part 11
• ICH Q10
• Pharmacopoeia of Japan only

Correct Answer: EU GMP Annex 1 (sterile medicinal products)

Q17. Which instrument provides both particle size distribution and particle concentration for non‑viable monitoring?

• Optical particle counter (OPC)
• Settle plate
• Liquid impinger
• Culture media incubator

Correct Answer: Optical particle counter (OPC)

Q18. Compared to settle plates, what is a major advantage of volumetric active air samplers for viable monitoring?

• They provide a quantitative concentration (e.g., CFU/m3) for a known sampled volume and are less dependent on gravitational settling
• They are cheaper and disposable in all cases
• They do not require incubation to obtain results
• They capture only dead organisms, making counts more stable

Correct Answer: They provide a quantitative concentration (e.g., CFU/m3) for a known sampled volume and are less dependent on gravitational settling

Q19. When should the flow rate of a volumetric air sampler typically be calibrated relative to a sampling event?

• Before and after each sampling session (or daily/each run) to verify correct volume sampled
• Only once when the sampler is first purchased
• Only when the sampler shows visible damage
• Calibration is unnecessary for air samplers

Correct Answer: Before and after each sampling session (or daily/each run) to verify correct volume sampled

Q20. What is a primary limitation of the settle plate (passive) method for airborne microbial monitoring?

• It underestimates airborne microorganisms because it relies on gravity and does not capture smaller or suspended particles effectively
• It provides immediate, real‑time quantitative data
• It measures particle size distribution accurately
• It is suitable as the sole method for validating a certified cleanroom

Correct Answer: It underestimates airborne microorganisms because it relies on gravity and does not capture smaller or suspended particles effectively

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