It includes atmosphere to fall dirt, wave dirt, gas collosol, of all sorts of building surfaces corrode, rustily content, sole and tire wear away content, plant branches and leaves, etc.

• 城市街道表面固形物系指沉积在城市街道的地表物。它包括大气降尘,飘尘,气溶胶,各种建筑物表面的腐蚀、锈蚀物,鞋底及轮胎磨损物,植物枝叶,等等。