Which refrigerant classification indicates a low toxicity for human exposure?

The classification that indicates a low toxicity for human exposure is A2L. This designation is part of the ASHRAE refrigerant designation system, where refrigerants are categorized based on their flammability and toxicity. The 'A' in A2L signifies that the refrigerant has low toxicity, which means it poses a reduced risk to human health upon exposure. The '2L' indicates that the refrigerant is mildly flammable, but its low toxicity is a crucial factor when considering safety for human interaction in case of a leak.

In contrast, other classifications such as A3 represent higher flammability and still fall under low toxicity but are not suitable when a greater emphasis on safety and low risk is required. B1 and C2 refer to higher toxicity levels, which makes them less desirable regarding human exposure safety. Understanding these classifications is vital for ensuring safety in environments where refrigerants are used.