Road transport allows all forms of land conditions to be met at less cost. Because of this function, despite numerous disadvantages, it becomes the most frequently used method of transport, especially in underdeveloped or developing countries. One of the most significant factors used in evaluating the atmosphere's air quality is the amount of CO2, increasing people's density in indoor spaces. The amount of CO2 indoors is, therefore, vital to determine. In this study, CO2 and temperature measurements made on nine different bus journey was made in Turkey. The minimum and maximum values were recorded as 555 ppm and 3000 ppm CO2, respectively, in the measurements. On all journeys, the average concentration is 1088.72 ppm. The minimum and maximum values were measured as 17.4 degrees C and 32.7 degrees C in the temperature measurements, and the average of all trips was calculated to be 25.76 degrees C. In this study conducted before the Covid-19 pandemic, it was determined that the amount of CO2 increased with the density and insufficient ventilation in the buses. The risk of infection increases in places with high human density and low clean air. For situations such as pandemics, CO2 measurement is a rapid indicator of determining human density.