Impact of urban air pollutants on the night sky brightness and color in Hohhot

Abstract

This study investigated the impact of urban air pollutants on the brightness and color of the night sky in Hohhot, China. The study used correlation analysis to determine the relationship between air pollutant concentrations and night sky brightness. Observations were conducted using a charge-coupled device(CCD) camera and an unmanned aerial vehicle (UAV) to assess changes in night sky brightness, color, and their spatial distribution before and after the aggravation of air pollution. The results revealed that particulate matter (PM) had the strongest correlation with night sky brightness among urban air pollutants, while the correlation between gaseous pollutants (except O3) and night sky brightness needs to be cautiously interpreted. The CCD camera observations showed that the night sky shifted toward red as the concentration of urban air pollutants increased. Meanwhile, the UAV observations demonstrated that the brightness of the night sky decreased with height above ground, and the area of night sky glow increased with higher urban air pollutant concentrations. Based on the research findings, controlling air pollutant emissions may have a positive impact on reducing the level and area of light pollution in the night sky, and thus promote sustainable urban environment development.