In my opinion, air pollution are the largest problem nowadays. Anyone can limit pollution - we only have to want! We can use bikes or go on foot instead of drive a car, because car exhausted fumes are harmful to the environment. If we must use the car, we can buy unleaded petrol. Our cars, motorbikes, factories produce a lot of carbon dioxide, so we need trees – our free oxygen factory. Unfortunately, deforestation is a serious problem – we have to protest against cut down forests.