Hazardous blanket (4)
I believe the answer is:
smog
(Other definitions for smog that I've seen before include "Visible air pollution" , "Pea-souper" , "Pollution haze/fog" , "Pollution fog" , "Polluted haze" .)
I believe the answer is:
smog
(Other definitions for smog that I've seen before include "Visible air pollution" , "Pea-souper" , "Pollution haze/fog" , "Pollution fog" , "Polluted haze" .)