In 1992, while making short documentaries to illustrate the challenges faced by the Rio Earth Summit, I visited the Brazilian city of Cubatao, known as one of the most polluted cities in the world. You could not eat the bananas that grew in abundance on the riverbank or the fish that shoaled in the "fresh" water. Oil refiners, steel makers and fertilizer producers put a stop to that, if you valued your health.

The US government had recently imposed tighter emission controls on its indigenous industry and, in the controversial economic philosophy of the time, Brazil had implored its northern cousins to export its polluting manufacturers to its shores so the consequent wealth they created would "trickle down" to the poor. Of course, it never did, but the toxins they brought with them did, leading to children being born without brains and mountainsides being denuded of forests.

I discovered a cemetery with the marble crosses in this Christian country covered in plastic bags to protect the precious inscriptions from the deleterious effects of acid rain. It enabled me to pen the catchy line that not even the dead were safe from the pernicious effects of pollution in this valley of death.