[Calvin Locke]

...harmful acidic gas

BFD. Nature does the same thing. When the Blues (Bluefish) are running, they chase Poagies (aka Menhaden) in to coves,
where they suck up all the 02 in the water and die.

The fumes from resulting decomposition peel the paint off of neighboring structures.

[optik_b]

Fighting the foam
City sanitary workers cross the bridge over the Tiete River in Pirapora do Bom Jesus, Brazil, 50 miles west of Sao Paulo, on July 5. Water is sprayed from nozzles underneath the bridge in an attempt to keep down the foam, which is generated by a mixture of chemical detergents and organic pollutants. The population of Pirapora de Bom Jesus, downriver from Sao Paolo, South America's largest city, has registered a 161 percent increase in cases of respiratory ailments since 1999