Was Impressionism "smoke and mirrors"?

Painting is smoke and mirrors. It's all an illusion. The palettes were from nature and not hand me down formulas. I would not think the subject matter invented the style but the style was well suited to the environment.
That's an interesting article. The atmospheric conditions of the time could have well played a part in palette selection, but Monet also suffered from worsening vision as he got older, and wouldn't do anything about it. He is said to have had cataracts, and it's a known phenonomenon that their presence will scatter light in unusual ways. People today with cataracts are advised not to drive at night because of this occurrence. Monet likely used it to his advantage.

James Whistler was also mentioned in the article - he was a Tonalist, painting in deliberate subdued palettes like his Nocturnes. Even his famous portrait of his mother follows the typical palette of Tonalism, and is an interior scene.

Not a great stretch to imagine different skies from countryside to city, so in that regard the smoky trains, boats, etc., could affect atmospheric haze.

Good link, though, and an interesting read.
Yeah some of those paintings were done in polluted hazy airs which gave those paintings more atmosphere than pre-industrial landscapes for sure. Couple that with the new industrial urban scenery and suddenly artists were seeing a new world in new ways and tubed paints helped also by getting artists outside. Plein air painting required beefy simple paint application. No time to make it perfect, just get the impression.
Until the 80s London was called 'The Smoke" by the English. Our cities in the US were choked with smoke and smog, not the least of which was LA followed by NYC, and places with industrial might. Coal burning choked many country towns from the 1700s on, I believe. But the level of smoke were noticeably higher to the inhabitants following the Industrial Revolution use of steam power (not the original cleaner water power.) Monet deliberately did note that haze and coloration in many of his urban paintings, long before his cataract problems. So the hypothesis is quite plausible.

Obviously, that is far from the only thing that spurred Impressionism. It's just one factor in depictions of larger cities and towns. Note that those painters were often impressed with and painted scenes of the industrial age innovations, like iron buildings and structures too. Not just the smoke but their entire environmental change. They were far from blind to the societal alterations of their day.
I believe the atmosphere of the times did affect artists. In a way it is apparent even now in cities as pollution again is evident. Even simple weather systems can cause "haze" that at times can be an issue, especially around the Med.
But also, Monet had his cataracts removed and the kens of his right eye removed it changed his colour vision and acuity