The Usage of fossil origin fuels is one of the most important cause of air pollution. The usage of these fuels unconsciously causes environmental problems especially air pollution. In this study air pollution parameters (SO2 ve PM10) were analyzed before and after the usage of natural gas in Karabuk. The effect of usage natural gas on air quality is researched. In this city before 2010 coal, foul-oil and diesel were used to provide heat demanded then it is started using natural gas by 2010. With starting the usage of natural gas, the usage of these kind of fuels (coal, foul-oil, and diesel) has been decreased. At the end of the study-in the Air Quality Assessment and Management Regulation (AQAMR)-it is concluded that the value of 250 mu g/m(3) for SO2 is over in some months before using natural gas but it hasn't exceeded 250 mu g/m(3) after starting the usage of natural gas. It has been identified that the value of 200 mu g/m(3) which is specified in regulations for PM10 has been exceeded and reached to 267 mu g/m(3) in the winter season. It has been observed that with starting the usage of natural gas, this value is again decreased in 2010. It is observed that while the usage of natural gas is getting more and more the value of SO2 ve PM10 are significantly decreased.