## 3 Results and Discussions
### Temporal Variation Characteristics of Atmospheric Particulate Matter Concentration
Concurrently, the PM\({}_{2.5}\)/PM\({}_{10}\) ratio stood at 0.81 on that day, signaling a pronounced severity in fine particulate matter pollution. Conversely, the acme of PM\({}_{10}\) concentration for the year was noted on 15 January, registering 272 \(\mathrm{\SIUnitSymbolMicro g}\).m\({}^{-3}\). Analyzing the PM\({}_{2.5}\)/PM\({}_{10}\) ratio for that day (0.80) alongside the PM\({}_{2.5}\) concentration (218 \(\mathrm{\SIUnitSymbolMicro g}\).m\({}^{-3}\)) underscores the gravity of atmospheric particulate pollution. This analysis underscores that during winter, Chenzhou City is predominantly afflicted by fine particulate matter pollution. Notably, the particulate matter pollution in the city exhibits a pronounced monthly concentration between October and February of the subsequent year, characterized by prolonged durations and significant fluctuations. Winter in Chenzhou City is marked by low temperatures and aridity, coupled with sparse rainfall. As autumn transitions into winter, there is an uptick in coal combustion for heating, resulting in escalated pollutant emissions. Meteorologically, the boundary layer diminishes during the colder months, persistently influenced by low humidity and stable atmospheric conditions. Furthermore, the city's proximity to the western Nanling and Luoxiao Mountains fosters pollutant accumulation. Collectively, these factors impede pollutant dispersion, culminating in sustained regional pollution accumulation. Upon scrutiny of Figures 2 and 3, pronounced seasonal disparities in particulate matter concentrations within Chenzhou City become evident. The hierarchy of PM\({}_{2.5}\) concentrations is as follows: winter (75.13 \(\mathrm{\SIUnitSymbolMicro g}\).m\({}^{-3}\)) > autumn (55.55 \(\mathrm{\SIUnitSymbolMicro g}\).m\({}^{-3}\)) > spring (42.37 \(\mathrm{\SIUnitSymbolMicro g}\).m\({}^{-3}\)) > summer (27.64 \(\mathrm{\SIUnitSymbolMicro g}\).m\({}^{-3}\)). The seasonal fluctuation patterns of PM\({}_{10}\) mirror those of PM\({}_{2.5}\). The sequence of its concentrations across the four seasons is winter (118.16 \(\mathrm{\SIUnitSymbolMicro g}\).m\({}^{-3}\)) > autumn (89.22 \(\mathrm{\SIUnitSymbolMicro g}\).m\({}^{-3}\)) > spring (78.67 \(\mathrm{\SIUnitSymbolMicro g}\).m\({}^{-3}\)) > summer (56.02 \(\mathrm{\SIUnitSymbolMicro g}\).m\({}^{-3}\)). This variation could stem from seasonal pollution sources--such as southward-traveling sand dust in autumn and winter, along with coal and straw combustion during these seasons--as well as industrial emissions and meteorological conditions. Upon integrating the insights from Figure 3, it becomes apparent that the PM\({}_{2.5}\) concentrations in spring exhibit anomalous values. This suggests that, during specific intervals in spring, the PM\({}_{2.5}\) levels surpassed the expected range. Primarily, the arid conditions and sparse precipitation in the Chenzhou region during spring fostered the formation of inversion layers and maintained atmospheric stability. Furthermore, a particular phase witnessed significant dust activity in the south, hampering the dispersion of both dust and vehicular emissions. This resulted in pronounced and erratic fluctuations in PM\({}_{2.5}\) concentrations throughout spring. In autumn and winter, abnormal values predominantly manifest after the heating season, underscoring the significant contribution of concentrated emissions from coal combustion to the prevailing fine particulate matter pollution in Chenzhou. Analogously, the anomalous PM\({}_{10}\) concentrations in spring are chiefly attributable to the influence of northern sandstorms. Influenced by the southern migration of dust, the atmosphere witnessed an escalation in the concentration of suspended coarse particles, leading to irregular and pronounced fluctuations. The median PM\({}_{10}\) concentration during spring markedly surpassed the seasonal average, signifying multiple episodes of coarse particle pollution in Chenzhou during the spring of 2022. This constitutes the primary pollution process.