Spatial representativeness of PM 2.5 monitoring stations and its implication for health assessment

Air pollution measurements from monitoring stations are widely used in health assessment, and it is important to take into account the spatial representativeness (SR) of stations when quantifying population exposure to air pollution measured in these stations. Using high-quality satellite-derived PM 2.5 data with 1-km spatial resolution over Yangtze River Delta (YRD) from 2016 to 2020, this study estimates SR of 213 PM 2.5 monitoring stations, and these SR estimates are further used to calculate annual population-weighted mean (PWM) PM 2.5 and deaths attributable to PM 2.5 exposure for each city in YRD. Our results show that SR areas of 213 stations totally account for 32.33% of the area of YRD, and the SR size varies greatly with stations. Additionally, we find that the city-level PWM PM 2.5 based on SR is nearly always larger than that using full coverage satellite-derived data. The difference tends to decrease as the population ratio of SR area increases. For the entire YRD, attributable deaths using PWM PM 2.5 based on SR are 182,009 (95% CI: 136,632–225,081), and are comparable to the ones derived using full-coverage satellite-derived data. Nevertheless, the relative change in attributable deaths is more than 6% in some cities due to the low population ratio of SR (less than 20%), which suggests that more monitoring stations should be deployed in these cities for human assessment.