When cleanup volunteer Sergei Solovev arrived in the town of Tuapse, on Russia’s Black Sea coast, an unpleasant odour hung in the air and everything was coated in a layer of black grime. “I saw train carriages covered in residue from the black rain and animals. It’s all very toxic,” he told Al Jazeera. “And the smell was oily.” Recommended Stories list of 4 items list 1 of 4 Ukrainian drones strike Russia’s Tuapse refinery for third time list 2 of 4 Ukraine targets Druzhba pipeline to sever Russian oil, influence in EU list 3 of 4 Five charts that show the rise of global militarisation list 4 of 4 At least three killed, more than 10 injured in Russian attacks on Ukraine end of list Black rain is an unnatural weather phenomenon, where water droplets blackened by soot and ash fall from the sky. It was seen in Hiroshima, Japan, after the atomic bomb explosion in 1945, more recently in the Iranian capital, Tehran, and in 1991 in Kuwait, when oilfields were set ablaze during the Gulf War.…