Related Clues:

• It may be thick in L.A. or Houston
• Airport hazard
• Unhealthy urban haze
• Subject of an alert
• Gray blanket
• Houston blight
• Troubling haze
• EPA worry
• 'Dongs of Sevotion' musician
• Unhealthy visibility reducer
• Pollution problem
• City scenery blurrer
• Industrial curse
• Hazy layer
• Pollution portmanteau