How often should there be a complete change of air within a storage room?

• A. Every 2 hours
• B. Every 30 minutes
• C. At least 6 times per hour
• D. Continuous

Answer: (C)

Ventilation rate is measured in air changes per hour (ACH), which tells you how many times the room’s air is replaced in an hour. For a storage room, good ventilation prevents buildup of fumes or vapors and helps keep oxygen levels safe.

The best choice sets a clear, sufficient pace: at least six air changes per hour. That means the room’s entire air volume is replaced roughly every 10 minutes, providing steady dilution of any released vapors and reducing concentration that could pose a hazard.

The other options are too slow or vague for this safety goal: every 2 hours is only 0.5 ACH, and every 30 minutes is about 2 ACH—both allow more time for vapors to accumulate. Continuous ventilation doesn’t specify a rate, whereas a quantified minimum like six changes per hour gives a concrete, enforceable standard.