Answer: smog

AnswerCrossword Clue
SMOG

Dirty haze

SMOG

Big-city problem

SMOG

London's Great ... of 1952

SMOG
Pollution-oriented portmanteau word
SMOG
Skyline obscurer
SMOGAir condition?
SMOGIndustrial-zone feature
SMOGClean Air Act concern
SMOGEnvironmentalist's concern
SMOGUrban hazard
SMOGAtmospheric pollution
SMOGUrban pall
SMOGTinseltown problem
SMOGUrban air problem
SMOGAir quality concern
SMOGUrban pollutant
SMOGUrban alert subject
SMOGUrban haze
SMOGCity scenery blurrer
SMOGTroubling haze
SMOGEnvironmental bane
SMOGUrban miasma
SMOGLos Angeles weather woe
SMOGUrban bane
SMOGCause of a bad air day?
SMOGPollution problem
SMOGUrban blight
SMOGUrban health concern
SMOGBeijing environmental issue
SMOGMegalopolis challenge
SMOGAir pollution
SMOGLondon woe
SMOGAir apparent?
SMOGFeature of a bad air day
SMOGAir blight
SMOGKind of haze
SMOGEPA concern
SMOGMaker of a bad air day
SMOGBig city problem
SMOGHazardous haze