A customer asks why R-134a is said to have an ozone depletion potential of zero. What is the reason?
Environmental impacts · EPA 608 Core. The correct answer, and the reasoning behind it.
How CFCs and HCFCs destroy stratospheric ozone, and what that does to health and the environment.
The question
A customer asks why R-134a is said to have an ozone depletion potential of zero. What is the reason?
- It breaks down completely in the lower atmosphere
- It contains no chlorine to attack ozoneCorrect answer
- It is heavier than air and stays near the ground
- It is used only in small amounts
Why “It contains no chlorine to attack ozone” is correct
R-134a is an HFC, made of hydrogen, fluorine and carbon. With no chlorine (or bromine) in the molecule, it cannot carry ozone-destroying atoms into the stratosphere, so its ODP is zero. Some HFCs still have a high global warming potential.
Source: EPA: Test Topics
Why the other answers are wrong
- It breaks down completely in the lower atmosphere — HFCs are not destroyed before reaching the upper atmosphere; they simply carry no chlorine.
- It is heavier than air and stays near the ground — Refrigerant vapors mix through the whole atmosphere over time regardless of density.
- It is used only in small amounts — The amount used has nothing to do with ODP, which is a property of the chemical.
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