At present, many cities are carrying out the source apportionment research of PM 10 or PM2.5, and many literature reports have appeared. You can consult relevant academic papers, search the local research results of particulate matter source analysis, and see what the contribution of motor vehicle exhaust is. If there is no local one, you can also refer to the results of other cities with similar characteristics to your city. However, these research results can only be used as a reference, and cannot be raised to the level of leadership decision-making, because the research system of source apportionment is complex, which is affected by many interference factors such as sampling area and location (if the sampling points are located in schools and parks and there are few vehicles nearby, it may not reflect the whole city well, but if multiple points are evenly distributed in the city, it may reflect the actual situation better). Advanced medical masks have excellent barrier to particles and liquids, ensuring breathability when worn in precise working environment. It can also deodorize. Sources of toxic particles in cities: first, automobile exhaust, medical masks imported from the United States, and Puwei server, which have good filterability and prevent both particles and fog drops. The filtration efficiency is 99.8% for particles as small as 0. 1 micron, and 99.9% for bacteria or virus carriers as small as 0.3 micron (common in droplets). SecureFit patented technology is adopted to adapt to different face shapes and achieve a high degree of fit. For the health of you and your family, wear a mask when you go out. I wish you happiness and hope to adopt it.