<p>Diesel vehicles are the primary mode of transportation in underground coal mines, widely used in mining regions such as Inner Mongolia and Shaanxi Province, China. However, their extensive use has led to growing concerns over diesel exhaust pollution in confined mine spaces. Carbon monoxide, a major pollutant in diesel exhaust, often results in localized concentrations exceeding 24 ppm, posing significant health risks to coal miners. This study utilizes a self-developed diesel exhaust experimental platform, with air speed as the variable, to investigate the characteristics of exhaust distribution under varying conditions. It also explores the diffusion and transport mechanisms of exhaust from diesel vehicles. The results demonstrate that CO concentration decreases with increasing distance from the exhaust source, following a “three-region” pattern. In Region I, molecular motion and concentration gradients cause a rapid reduction in CO. In Region II, convection and diffusion further dilute the CO, while in Region III, the concentration stabilizes and becomes more evenly distributed. These changes are attributed to the unique operational conditions of diesel vehicles and the fluid dynamics of exhaust diffusion. High concentrations of CO accumulate near the exhaust pipe, where dilution is slow. However, increased air speed accelerate CO reduction, with concentrations continuing to decrease as the distance from the exhaust outlet increases. The CO concentration was observed to decrease from 95.1 ppm to 9.5 ppm, a reduction of 90.01%. Comparisons of field and experimental data confirm the reliability of the experimental platform. These findings highlight the diffusion and jetting effects of CO concentration and offer engineering guidance for CO management in vehicle exhaust in coal mines.</p>