In The Fifth Element the city of New York appears to have a perpetual layer of fog clinging to its lower levels. Presumably this fog reaches all the way to the ground, but I don't recall this being mentioned in the movie.
Is there any official information on just how deep this fog was? Was it just a few hundred feet, or was it several miles?
I'm not aware of any canonical answer to the question, since all we really have for that "universe" is the movie itself, and the movie doesn't say. Visually, there's a suggestion that the fog extends from the ground to the equivalent of skyscraper height, thus causing New Brooklyn to reach even higher to escape it.
Speculating, I would think that the fog at the lowest levels is probably downright toxic and that Corbin only descended far enough down as he needed to to hide.
If TFE had become more of a franchise, it might have been interesting to see some exploration of what, if, anything, lives at those lower levels and what part they play in the culture of that time. As it is, TFE stands alone, and all we can do is wonder!
We can use the novelisation and images from the film to come up with a lower and upper bound for the depth of the smog.
Korben's taxi leveled off a few seconds after it entered the smog layer.
Korben’s cruiser turned turtle and dove — straight down, through the startled scurrying cabs and flivvers and maglev limos. He powered up at the last minute, just above the garbage that covered the street.
Rubbish covers the entire lower layer of the city, up to a height of at least 20 feet
The deepening haze and smog that clung to the ground level of the city mercifully obscured the generations of litter and debris—the urban midden that covered the streets to a depth of between twenty and forty feet.
The billboard is 50 feet high.
The young cop scanned the billboard, which was fifty feet high but only ten wide, not nearly wide enough to hide a cab.
Given that the smog is higher than a 50 foot high billboard (which itself is at least 40 feet off the ground) we can determine that the minimum depth that the smog can possibly be is 90 feet. Since Korben nearly hit the ground in his dive, the implication is that the top height of the smog layer is between 200-500 feet.
It's probably the case that as antigravity systems became more and more popular cities were able to be built higher to escape centuries of pollution, maybe lots of other cities have the same issues considering it seems that the flying cars still seem to emit some form of exhaust fumes too so the issue may still continue.
As the water level in the movie seems to have inexplicably dropped it seems that the land around Manhattan and the bridges have been built on, so perhaps it is only a problem with central Manhattan or NY in general, in the wide-angle of the city as the plane leaves for Fhloston you can see the fog surrounding the city where the river used to be, so it might be a case of some of the newer areas were designed to sit 'under' the fog.
One theory was that the entire city was lifted to escape the fog but Luc Besson stated that the ocean levels have dropped because they took it for terraforming other worlds, however this would make little sense as there is plenty of water ice and asteroids to mine in the galaxy
However, it'd be interesting to see other cities in this universe, such as London without the Themes or Venice with multitudes of flying gondolas, although there's no real sustained theory as to why the water level has dropped apart from taking it for terraforming, but I doubt it has any relation to the fog.
