Separating Daily 1 km PM_2.5 Inorganic Chemical Composition in China since 2000 via Deep Learning Integrating Ground, Satellite, and Model Data

Abstract

Fine particulate matter (PM 2.5 ) chemical composition has strong and diverse impacts on the planetary environment, climate, and health. These effects are still not well understood due to limited surface observations and uncertainties in chemical model simulations. We developed a fourdimensional spatiotemporal deep forest (4D-STDF) model to estimate daily PM 2.5 chemical composition at a spatial resolution of 1 km in China since 2000 by integrating measurements of PM 2.5 species from a high-density observation network, satellite PM 2.5 retrievals, atmospheric reanalyses, and model simulations. Cross-validation results illustrate the reliability of sulfate (SO 4 2− ), nitrate (NO 3 − ), ammonium (NH 4 + ), and chloride (Cl − ) estimates, with high coefficients of determination (CV-R 2 ) with ground-based observations of 0.74, 0.75, 0.71, and 0.66, and average root-mean-square errors (RMSE) of 6.0, 6.6, 4.3, and 2.3 μg/m 3 , respectively. The three components of secondary inorganic aerosols (SIAs) account for 21% (SO 4 2− ), 20% (NO 3 − ), and 14% (NH 4 + ) of the total PM 2.5 mass in eastern China; we observed significant reductions in the mass of inorganic components by 40−43% between 2013 and 2020, slowing down since 2018. Comparatively, the ratio of SIA to PM 2.5 increased by 7% across eastern China except in Beijing and nearby areas, accelerating in recent years. SO 4 2− has been the dominant SIA component in eastern China, although it was surpassed by NO 3− in some areas, e.g., Beijing−Tianjin−Hebei region since 2016. SIA, accounting for nearly half (∼46%) of the PM 2.5 mass, drove the explosive formation of winter haze episodes in the North China Plain. A sharp decline in SIA concentrations and an increase in SIA-to-PM 2.5 ratios during the COVID-19 lockdown were also revealed, reflecting the enhanced atmospheric oxidation capacity and formation of secondary particles.

Gestational and Postpartum Exposure to PM2.5 Components and Glucose Metabolism in Chinese Women: A Prospective Cohort Study

“…The toxic components of PM 2.5 may have heterogeneous spatiotemporal distributions and various emission sources . In China, NO 3 – is mainly distributed over the economically developed cities and industrial centers, constituting about 19.8% of total PM 2.5 . We observed a significant effect of NO 3 – even with lower composition proportions (about 12% to 13%) and concentrations (mean 4.0 and 5.0 μg/m 3 ) than the national average and previous study, emphasizing the importance of continued effort for controlling NO 3 – sources in China.…”

“…40 In China, NO 3 − is mainly distributed over the economically developed cities and industrial centers, constituting about 19.8% of total PM 2.5 . 41 We observed a significant effect of NO 3 − even with lower composition proportions (about 12% to 13%) and concentrations (mean 4.0 and 5.0 μg/m 3 ) than the national average and previous study, 30 emphasizing the importance of continued effort for controlling NO 3 − sources in China. Several potential mechanisms have been proposed to explain the linkages between PM 2.5 and maternal glucose metabolism.…”

Exposure to Fine Particulate Matter Constituents and Human Semen Quality Decline: A Multicenter Study

“…The CHAP is an extensive, high-resolution, high-quality dataset of ground-level air pollutants within China that is generated by integrating artificial intelligence and big data, such as ground-based measurements, and satellite remote-sensing products, considering the spatial and temporal heterogeneity of air pollution. Its validity has been verified in previous studies. , Daily concentrations of PM 2.5 chemical constituents were extracted from this dataset based on subjects’ residential addresses to assess individual exposure. Since human sperm development takes an approximate 90 day period and PM 2.5 constituents are usually not normally distributed over this period, we chose the median concentration from 0 to 90 days prior to the semen donation date to assess individual exposure to PM 2.5 and its constituents.…”

Modification of Food Allergy on the Associations between Early Life Exposure to Size-Specific Particulate Matter and Childhood Allergic Rhinitis

“…In situ determination of daily PM 1 from the China Atmosphere Watch Network and ground-based monitoring data of daily PM 2.5 and PM 10 from the China Urban Air Quality Real-Time Publishing Platform from 2013 to 2018 were collected. The method of model development in this study has been described in detail in our previous studies. − …”