While writing about such big problems it’s important to follow a couple of rules. Scientific essays require us to show clearly what we’re talking about as well as to defend our hypothesis. That is why, we’re gonna start off with a hypothesis and continue with a definition:
Define the topic - Writing ‚about pollution’ is not enough for a good essay. What you need is a statement you will base the whole argument on. For example, you could say:
Pollution is one of the biggest problems of the modern world
It’s good to include some general numbers showing the scale of the problem as well. All in all the first paragraph shouldn’t be longer than 2~3 sentences.
Explain the nature of the problem - if you are starting a dispute, you should lay down the nature of the problem. We will analyze it based on some kind of definition which we need to include here. It can be taken from a dictionary, for example:
pol·lu·tion (pə-lo͞o′shən) n.
I. the act of polluting or the state of being polluted
II. harmful or poisonous substances introduced into an environment
Support your ideas with appropriate arguments - We said that pollution is a big problem, so now, we only need to present facts, that will confirm that hypothesis. Firstly, you could say that it affects everything: water, ail, land, soil and even our hearing. Another great option is to explain how deforestation and air pollution influence changes the climate destroying natural habitats of many species of animals, try to express that the Mother Nature helps us every day and in return we destroy her children. We can already see the climate change since the process started good couple years ago. Summers are hotter and winters become really mild, the truth is that even though we dont’s see it too well, it’s stil there.
Sum up - Pollution itself is actually quite hazardous for people as well so it seems like a good point to start the summary for your essay. Wrap things up and either confirm or reject your original hypothesis. Of course, in order for your essay to look better you should rahter work on confirmation more than rejection.
I hope it's enough to help you :)