Concentration of formaldehyde that requires UN 3334 Aviation regulated liquid n.o.s.?

• A. Less than 10%
• B. Only those containing alcohol
• C. Between 10% and 25%
• D. 25% or more

Answer: (C)

Concentration thresholds determine when formaldehyde solutions are treated as an aviation-regulated liquid. UN 3334 Aviation Regulated Liquid, n.o.s. applies to formaldehyde solutions within a specific range—10% to 25% formaldehyde by weight. Within this window, the hazard level is high enough to require the stricter air-transport controls, so shipments must follow the aviation-regulated liquid rules. If the solution is below 10%, it doesn’t meet the UN 3334 window and typically isn’t governed by this designation (it may be exempt or fall under another classification). If the concentration reaches 25% or more, it moves out of this UN 3334 category and would be handled under a different UN number or regulatory requirements appropriate to its higher hazard. That’s why the correct range is between 10% and 25%.