Which safety classification is most dangerous to use?

Which safety classification is most dangerous to use?

• A. B3
• B. A1
• C. C1
• D. A3

Answer: (A)

High hazard comes from a classification that shows both high toxicity and high flammability. In this system, toxicity is labeled with letters (A = lower toxicity, B = higher toxicity) and flammability with numbers (1 = nonflammable, 2 = moderately flammable, 3 = highly flammable). The most dangerous to use is the one that combines a high toxicity rating with a flammability rating of 3, because it poses serious health risks even with brief exposure and can ignite or burn readily. The other possibilities are less dangerous in at least one dimension: some are safer overall (low toxicity and nonflammable), while others are hazardous mainly due to flammability or mainly due to toxicity, but not both to the extreme.

High hazard comes from a classification that shows both high toxicity and high flammability. In this system, toxicity is labeled with letters (A = lower toxicity, B = higher toxicity) and flammability with numbers (1 = nonflammable, 2 = moderately flammable, 3 = highly flammable). The most dangerous to use is the one that combines a high toxicity rating with a flammability rating of 3, because it poses serious health risks even with brief exposure and can ignite or burn readily. The other possibilities are less dangerous in at least one dimension: some are safer overall (low toxicity and nonflammable), while others are hazardous mainly due to flammability or mainly due to toxicity, but not both to the extreme.