Everyday use of traffic has its impact on environment. There are still attempts to reduce that impact and trying to make energy savings, but the world is still not aware what traffic does to nature and in what way it all has impact on us. Each mode of transport has its advantages and disadvantages, but there are still so many downsides that have not yet been corrected and there is much to do to make them better. Man is still unaware of what he has done to the environment by using traffic in that amount, how much the environment is actually polluted per day, and to what extent man is doing himself a disservice. The railway, that is the most environmentally friendly, is failing and not developing, while road transport, which is the worst for the environment and has bad affects on people and the environment, is constantly developing and every year there are more and more road users. This paper presents all the ways in which different modes of transport can affect the environment. Examples are Karlovac County, Slunj, Rakovica and Plitvice Lakes. External costs are shown and how much they can amount to. The goal of this paper is to show how the environment is polluted by traffic, but also how the environment can be less affected and how people can reduce pollution to a minimum.