Related Clues:
- Lightning byproduct
- Kind of layer protecting the earth
- Layer with a hole in it
- Earth-surrounding layer
- Water sterilizer
- Threat to alfresco artwork
- Environmental woe
- Oxygen variety
- Endangered atmospheric layer
- Ultraviolet-ray blocker
- Ultraviolet light filter
- Oxygen allotrope
- Damaged layer
- Shrinking layer
- Layer to be concerned about