Gerry Ellis / Gas effluence pouring out of smoke stacks at nuclear power plant, upper Ohio River, Ohio

Pete Oxford / Gas burn-off stations along Napo River, Amazon, Ecuador

Ingo Arndt / Smoke emerging from power plant stacks, Lake Powell area, Utah

Luciano Candisani / Industrial pollution near atlantic rainforest, Sao Paulo, Brazil

Albert Lleal / Thermal power plant with tall smoke stacks, Barcelona, Spain

Colin Monteath / Wood processing plant near Christchurch showing gas effluents, New Zealand

Colin Monteath / Factory chimneys belch smoke, winter smog makes it hard to see houses between trees, Christchurch, Canterbury, New Zealand

Colin Monteath / Steaming fumaroles at sunset, Mt Erebus, Ross Island, Antarctica

Gerry Ellis / Gas effluence from nuclear power plant, upper Ohio River, Ohio

Pete Oxford / Fumaroles at 4850 meters, altiplano region, Sol de Manana, southwestern Bolivia

Luciano Candisani / Industrial pollution near atlantic rainforest, Sao Paulo, Brazil

Chien Lee / Noxious hot fumes escape from a volcanic vent on Mount Papandayan leaving behind deposits of sulfur, Indonesia

Chien Lee / Noxious hot fumes escape from a volcanic vent on Mount Papandayan leaving behind deposits of sulfur, Indonesia

Chien Lee / Noxious hot fumes escape from a volcanic vent on Mount Papandayan leaving behind deposits of sulfur, Indonesia

Chien Lee / Noxious hot fumes escape from a volcanic vent on Mount Papandayan leaving behind deposits of sulfur, Indonesia

Colin Monteath / Factory chimneys belch smoke, winter smog makes it hard to see houses between trees, Christchurch, Canterbury, New Zealand