Objectives  Since China's haze pollution to some extent accompanies urban sprawl, whether urban sprawl has exacerbated China's haze pollution is still unclear. Thus, exploring the effect of urban sprawl on haze pollution will provide a scientific reference for China to build a sustainable urban development path.

  Methods  Based on the NPP-VIIRS (national polar-orbiting partnership's visible infrared imaging radiometer suite) nighttime light data, we first comprehensively calculate the index of urban sprawl.Then, through the construction of a panel data model for 204 sample cities in Chinse mainland at the prefectural level, the empirical analysis of the effect of urban sprawl on haze pollution is conducted.Also, the driving mechanism of urban sprawl's effect on haze pollution is comprehensively identified by means of mediating effect method.

  Results  Compared with the original NPP-VIIRS data, the corrected NPP-VIIRS data performs better results which could more accurately reveal the gross domestic product, electric power consumption, and population in China. It's verified that the nighttime light data can be a good substitute for statistical data to measure and quantify the urban sprawl index. Urban sprawl will aggravate smog pollution and this result has passed the robustness test after removing cities in the heating area.We find urban sprawl indirectly affected on haze pollution mainly through hag glomeration effects, land urbanization effects, and industrial structure effects. Specifically, in the process of urban sprawl in China, the increase of population size, the rapid expansion of construction land, and the high proportion of secondary industry value are the important key factors for the aggravation of haze pollution.

  Conclusions  We provide a new perspective to reveal the effect of urban sprawl on haze pollution from the nighttime light data. We suggest the control of haze pollution should be based on the actual situation of China and formulate a haze control policy suitable for the conditions of China.