The study measured the effects of urban pollution on two plant species. They found that the plants absorbed different amounts of lead and cadmium, affecting their leaf mass and pigments. Plants in heavily polluted areas had lower chlorophyll levels but higher carotenoid levels. Lead and cadmium decreased chlorophyll content but increased leaf mass. One plant species had increased leaf mass with more lead, while the other did not show a significant change. Leaf mass, chlorophyll ratio, and chlorophyll content can be used as indicators of urban air quality.