Breathe by Sage Roffe

Half died in the first twelve years, another half will die before help from Earth can arrive.
On a world turned toxic by the Belch, an industrial catastrophe that spewed hundreds of tons of Xenochem-646 into the air, the survivors concentrated in one central city scrabble and scrape for every molecule of oxygen they can get. To breathe the unfiltered air is to invite 646 into your lungs, where it dissolves you from the inside-out until you’re nothing but a jumpsuit filled with red slurry.
Rose has spent half her life looking through the tinted lenses of a gassie, staring up at the massive corpo towers of the great titans of industry. Towers where she’s heard that some people don’t even have seal-welts, and the very hollow suits who caused the Belch are skimming oxygen and selling it at a premium to the Jacks whose planet they ruined.
But Rose has something the corpos don’t. She’s got access to excavation-grade explosives, she’s got a crew of willing degenerates.
And most dangerous of all, she’s got a plan.