For all the talk of what humankind has done to cause destruction to the planet, we should not forget that nature itself is a powerful force, capable of doing damage on a huge scale. The greenhouse (i) _____ and the hole in the ozone layer are indeed made worse by the industrialized society we live in. However, we must remember that there are certain species of plant and animal which, quite naturally, (ii) _____ offgases that are very harmful to the atmosphere. And only fifty years ago in London, hundreds of people died from the smog which hung over the River thames. What is interesting here is that, yes, smoke and gases from industry, vehicles and fossil (iii) _____ were ingredients in this deadly mixture. The other vital ingredient, though, was the completely natural fog, and who would have thought that could be harmful? In the early days of the industrial revolution, poets, painters and philosophers described how the polluted urban skies made them think of the end the world. Well, towards the end of the nineteenth century, the volcanic eruption of Krakatoa nearly made it happen! Though of tons of dust and ash were thrown into the air and, for years afterwards, there were red sunsets caused by the light filtering through this natural pollution. Remembering scientists pet theory about the dinosaurs (iv) _____ out because of a huge volcanic eruption, we were lucky that humankind survived this time. So next time you look out from your garden or balcony and see a beautiful red sunset, think of the possibilities. It could be the result of our activities poisoning the air we breathe, or it might just be (v) _____ turning on the radio to check there haven’t been any major eruptions lately!
(iv)______
