The quantity of carbon dioxide contributed by automobile emissions to the environment was determined at some area in Abeokuta and Sango Ota metropolis of Ogun State ,Nigeria.The study was performed in selected populated areas of vehicle in the two towns. In Abeokuta, the study was conducted in 5 areas, Sapo/1, Ibara, Lafenwa, Adatan and Panseke area. While in Sango Ota, 5 was also conducted at Sango Ota area namely Sango garage, Owode, Idi iroko road (under bridge), Iyana iyesi and Ota junction. A gas sampling pump and tubes that could detect carbon dioxide were used to detect the quantity of carbon dioxide in the environment. The result obtained shows a variation in the amount of carbon dioxide in the environment. Areas with relatively heavy congestion show high concentration of carbon dioxide while area of minimal traflic shows a lower concentration of carbon dioxide. The literature shows that increasing carbon dioxide level have adverse effects such as the greenhouse eflect, which may lead to Global warming, as well as a number of other climatic events. These concentrations are still not high enough to cause any serious health eflects but they provide a baseline study for policy makers.