As a matter of fact, air pollution has only recently become an environmental issue of significant concern. There are many potential sources of pollution, but automobiles constitute the most significant single contributor. Vegetation planted along the roadside improves air quality significantly. In this study, two of Dehradun’s most well-known plant species had their Air Pollution Tolerance Index (APTI) measured, i.e., mango (Mangifera indica) and the lychee (Litchi chinensis). The photosynthetic pigments of these species were also analyzed, and PM10, SO2, and NO2 levels in the air were measured. The APTI was determined by measuring four variables: acidity, water activity, chlorophyll concentration, and ascorbic acid concentration. The proposed study shows the highest pollution at the ISBT location (out of the three selected sites) and the lowest at the control site (Graphic Era University). All the analysis led us to the conclusion that the mango tree is more resistant to pollution than the litchi tree, with photosynthetic pigment levels being higher at the control site and lower at ISBT. The city of Dehradun may benefit from better air quality and reduced pollution levels if more trees were planted along its highways.