Study Guide
Lesson 2/52Free

Ozone Layer & Ozone Depletion

Understand the ozone layer, how refrigerants destroy it, and the ODP rating system.

5m read

The Ozone Layer

The ozone layer is located in the stratosphere, approximately 10 to 30 miles above Earth's surface. It absorbs most of the sun's harmful ultraviolet (UV-B) radiation, protecting life on Earth from skin cancer, cataracts, and immune system suppression. Without this protective layer, UV radiation reaching the surface would increase dramatically.

The ozone layer is in the stratosphere and protects Earth from harmful UV-B radiation.

How CFCs Destroy Ozone

When CFC and HCFC refrigerants reach the stratosphere, UV radiation breaks them apart, releasing chlorine atoms. These chlorine atoms act as catalysts, destroying ozone molecules in a chain reaction. A single chlorine atom can destroy up to 100,000 ozone molecules before being deactivated.

One chlorine atom can destroy up to 100,000 ozone molecules through a catalytic chain reaction.

Refrigerant Types & ODP

CFC ODP & characteristicsHighest ODP; R-11 = 1.0 (the baseline)
HCFC ODP & characteristicsLower ODP; R-22 = 0.055
HFC ODP & characteristicsODP = 0 (no chlorine)
HFO ODP & characteristicsODP = 0, very low GWP
Key element causing depletionChlorine (not fluorine)

UV Health Effects & Environmental Damage

Increased UV-B radiation from ozone depletion leads to higher rates of skin cancer, cataracts, and immune system suppression in humans. It also damages crops, reduces plankton populations in the ocean, and disrupts ecosystems. This is why phasing out ozone-depleting substances is a global priority.

Ozone depletion increases UV radiation, causing skin cancer, cataracts, and immune suppression.

Ozone Depletion Review

  • The ozone layer is in the stratosphere and blocks harmful UV-B radiation.
  • Chlorine atoms from CFCs and HCFCs destroy ozone; one atom can destroy 100,000 ozone molecules.
  • ODP baseline: R-11 = 1.0 (CFC). R-22 (HCFC) = 0.055. HFCs = 0.
  • HFCs have zero ODP but still have high Global Warming Potential (GWP).
  • Increased UV causes skin cancer, cataracts, and immune suppression.