Nowadays the most actual problem of the big cities is air pollutant emissions from roads and mechanical vehicles, because they constitute the most important part in the urban realm. The purpose was to study reasons of air pollution by highway transportation and find out how to reduce these polluting emissions in the air. So the study objects in this article were polluting emissions, its chemical composition, arias of the maximum concentrations of repugnant substance. To avoid negative aftermath from the exhaust the gas or the alternative fuel have to be used in the mills of automobile transportation. It would help to stop further pollutions. Also the city lay-out has the great importance for the amount of toxic substances in the air. The city should have special location considering wind rose. And in the places there the wind enters the city and gets out of the city should be planted landscaped areas. These landscaped areas would clean the air in the city and out of it. Likewise the urban green belt would have positive impact on air. The practical importance of this thesis was processing of new methods and technologies for solving the problem of air pollutant emissions from roads and mechanical vehicles to reduce the amount of harmful exhaust into atmosphere. Because clear air is the basis of the civic health.