Abstract: The heavy metal content, temporal and spatial pollution characteristics and health risk levels of surface dust on some primary and secondary schools in the main urban area of Lanzhou city was studied, and the relationship between the monthly average heavy metal content of dust and the Nemeiro comprehensive pollution index and the climate environment was explored. The results showed that the seasonal average content of Cr, Ni, Cu, Zn and Pb in the campus dust in the main urban area of Lanzhou city exceeded the soil background value of Lanzhou city, and the overall performance was higher in winter than in summer. High values areas of Cr and Ni were concentrated in the west and the solid area was distributed in clusters. The areas with high Pb content were concentrated in the middle of the Chengguan area. The high values of Cu and Zn were unevenly distributed in the main urban area. Cu, Zn, and Pb were seriously polluted, and heavy pollution occured mostly in autumn and winter. The level of comprehensive pollution was severe in winter, low in spring and summer, and unstable in autumn. The non-carcinogenic risk of different exposure routes of heavy metals to juvenile from big to small was hand-oral exposure, skin exposure, respiratory exposure, and the non-carcinogenic risk was in the order of Zn, Pb, Ni, Cr, Cu. Carcinogenic heavy metals Cr and Ni had low carcinogenic risks. The monthly average precipitation, wind level and southeast wind had significant correlations with the heavy metal content of dust and the Nemeiro comprehensive pollution index. The heavy metal pollution on campus mainly came from outside the school.

Key words: school, heavy metals, spatio-temporal distribution, health risk, Lanzhou city