BRT (Bus Rapid Transit) public transport systems, are highly frequented micro environments by the population of a city. In this research a TSI DustTrak II was used to determine the PM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2.5</sub> concentration inside the buses of the BRT system in Bogotá, and a GPS app, MyCarTracks®, to record the speed and location data. Measurements were performed in three different segments of the system, and in different seats inside the buses. PM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2.5</sub> concentration levels above 120 μg/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> were measured for all the segments. Time travels of the BRT passengers was determined to be around 20 to 40 minutes average, where they are exposed directly to these high levels of pollution. Thereafter, a CFD model was implemented to simulate and assess the behavior of the tailpipe emissions. Contours of concentration showed the self-pollution phenomenon as a fraction around 18% of the total concentration of PM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2.5</sub> measured inside the cabin of the BRT.