The study looked at pollution levels of benzene, toluene, and xylene inside passenger cars in Tangshan. They tested 122 cars and found that 66.4% did not meet the pollution standards. Cars used for less than six months had higher levels of these compounds, which decreased over time. Cars with adsorbents had lower benzene levels, high-grade cars had higher toluene levels, and cars with leather seats had higher xylene levels. The study shows that the concentrations of these compounds inside cars are influenced by factors like usage time, car grade, and seat material.