Related Clues:

• Unhealthy visibility reducer
• Chimney dirt
• Coal dust
• Flue accumulation
• Sweep's collection
• Santa's laundry stains
• Chimney sweep's grime
• Pollution problem
• City scenery blurrer
• Stain on Santa's coat, you'd think
• Industrial curse
• Lampblack source
• Flue deposit
• Schmutz on Santa
• Flue substance