ALAT Facility Environment and Management 2 — Questions and Answers
Question 1: What is the recommended number of air changes per hour (ACH) in a conventional laboratory animal room?
- 5–10 ACH
- 10–15 ACH
- 15–20 ACH (Correct answer)
- 20–25 ACH
Correct answer: 15–20 ACH
The Guide for the Care and Use of Laboratory Animals recommends 15–20 air changes per hour in conventional animal rooms to maintain air quality.
Question 2: Which type of ventilated cage system draws air through a filter into the cage interior, creating a positive pressure environment relative to the room?
- Individually ventilated cages (IVC) in exhaust mode
- Static microisolator cages
- Individually ventilated cages (IVC) in supply mode (Correct answer)
- Open-top wire-bar cages
Correct answer: Individually ventilated cages (IVC) in supply mode
IVCs in supply (positive-pressure) mode push HEPA-filtered air into the cage, protecting immunocompromised animals from environmental pathogens.
Question 3: A technician notices condensation forming on the interior walls of an animal room. This MOST likely indicates:
- Temperature is set too low
- Relative humidity is too high (Correct answer)
- The HVAC system is working correctly
- Carbon dioxide levels are elevated
Correct answer: Relative humidity is too high
Condensation on walls indicates excessive relative humidity, which can promote microbial growth and must be corrected.
Question 4: Under the Guide recommendations, what is the acceptable relative humidity (RH) range for most laboratory animal species?
- 20–30%
- 30–40%
- 30–70% (Correct answer)
- 70–90%
Correct answer: 30–70%
The Guide recommends maintaining relative humidity between 30–70% to support animal health and comfort.
Question 5: Which lighting schedule is commonly used for rodents to standardize circadian rhythms in a research setting?
- Continuous light (24 hours on)
- 12 hours light / 12 hours dark (Correct answer)
- 8 hours light / 16 hours dark
- 18 hours light / 6 hours dark
Correct answer: 12 hours light / 12 hours dark
A 12:12 light-dark cycle is the standard photoperiod used for most laboratory rodents to regulate circadian biology.
Question 6: What is the primary purpose of maintaining a positive-pressure corridor outside animal holding rooms in a barrier facility?
- Prevent animals from escaping into the hallway
- Keep contaminants from entering the clean animal rooms (Correct answer)
- Reduce noise from entering the animal areas
- Maintain warmer temperatures for tropical species
Correct answer: Keep contaminants from entering the clean animal rooms
Positive pressure in the corridor relative to rooms outside the barrier prevents unfiltered air from entering the clean zone.
Question 7: A mouse room has an ammonia odor. Which management change would MOST directly address this problem?
- Increase lighting duration
- Decrease the room temperature
- Increase cage change frequency (Correct answer)
- Reduce air changes per hour
Correct answer: Increase cage change frequency
Ammonia accumulates from urine breakdown; increasing cage change frequency reduces bedding saturation and ammonia buildup.
ALAT Facility Environment and Management 2
What is the recommended number of air changes per hour (ACH) in a conventional laboratory animal room?