1905, blend of smoke and fog, formed "after Lewis Carrol's example" [Klein; see portmanteau]. Reputedly coined in reference to London, and first attested there in a paper read by Dr. H.A. des Voeux, treasurer of the Coal Smoke Abatement Society, though he seems not to have claimed credit for coining it.
At a recent health congress in London, a member used a new term to indicate a frequent London condition, the black fog, which is not unknown in other large cities and which has been the cause of a great deal of bad language in the past. The word thus coined is a contraction of smoke fog "smog" — and its introduction was received with applause as being eminently expressive and appropriate. It is not exactly a pretty word, but it fits very well the thing it represents, and it has only to become known to be popular. [Journal of the American Medical Association, Aug. 26, 1905]
Smaze (with haze (n.)) is from 1953.