Related Clues:

• L.A. issue
• Toner ingredient
• It should cover Santa
• Some particulates
• Pollution on some bricks
• Exhaust issue
• Grate film
• Cause of some urban coughs
• Grate stuff?
• Black buildup
• Chimney sweep's removal
• Air woe watched by the EPA
• Visibility obstructer
• Urban health problem
• Stack buildup