The study focused on understanding how pollutants build up and wash off surfaces in urban areas to help create better stormwater pollution control plans. Researchers studied roads and roofs to see how pollutants accumulate over time. They found that build-up happens quickly at first, then slows down. Rainfall plays a big role in washing off pollutants. Different surfaces have different build-up patterns, with roads being more dynamic. Finer particles get washed away, leaving coarser ones behind. This information can help improve models for predicting stormwater pollution.