Rotted Souls and Polluted Atmospheres

There is a stench once you enter the atmosphere.
A horrible stench that smells like what you might imagine a liquefying corpse would times infinity. It nauseates you, and if there were any contents in your stomach you are sure they would have found their way up, making their own, rather unremarkable contribution to the stench.

You move closer to the planet which the atmosphere you just came through belongs to, and the stench gets stronger. So strong that it burns your lungs and makes you scream in pain.
When the polluted air enters your nose and mouth and runs through your insides it feels like they are etched away by acid, burning up from the inside out. It’s so hard to breathe that you would rather choke, but your curiosity has been irked now, and you need to know where this is coming from. You need to know what is killing you.

You let yourself fall further towards the little planet, and things start to take shape beneath you.
There are mountains stretching up from the continents towards the stars, and there are oceans and lakes all over. Coming even closer you see cities forming large spots of urban decay on the planet’s otherwise so beautiful surface, and roads snaking their way across the land like snakes. And you fall further.

Then you stop. You’re right above a city, and you’re unable to breathe any longer as the stench in the air is now so acidic that it is burning up your eyes, making you go slowly blind.
Your skin, to, can feel the effect now; it is starting to fall off your body like a snake changing it’s scaly skin.

Through all this, the pain and blindness, your slow death, you have come to a realization.
The pollution in the air comes from the spirits of the people on the planet down beneath you. The stench is the scent of the rotting human souls.