Smog: The Original Instagram. In the 1970s, when the Clean Air Act (signed by Nixon in 1970) was just getting on a roll, the nascent EPA commissioned a series of photographs for the Documerica project to record pollution in America. They’re still pretty compelling; check out the rest here.
Argentine artist Nicolás García Uriburu dyes polluted bodies of water using fluorescein, a pigment which turns a bright green when synthesized by microorganisms in the water. Uriburu has been doing this for decades to raise awareness of worsening water pollution.