Objective: To propose an improved method for constructing the internal quality control (IQC) framework for ELISA assays and validate its efficacy by statistically analyzing IQC data from nine blood center laboratories. Methods: 1) IQC data was collected from nine blood centers and analyzed using a domestic HBsAg ELISA detection kit as an example. 2) Differences between IQC values across batches within Blood Center 1 were assessed. 3) Statistical analyses were performed on batch usage, number of batches used, days of use, number of QC points, batch-specific means, and coefficients of variation (CV) across all nine centers. 4) Using the improved construction method for IQC framework, provisional and permanent frames were established for batches within Blood Center 1 and Blood Center 9, followed by outlier determination. Results: 1) Statistically significant differences were observed in IQC data between batches within Blood Center 1 (P<0.01). It is recommended that both the control material/reagents and the control chart framework be replaced simultaneously. 2) There were substantial differences among 9 blood centers regarding the control material/reagent lot numbers used, the number of QC runs per batch, and the QC values for identical lots. Therefore, individual laboratories should establish their own IQC chart frameworks. 3) The improved IQC framework construction method for ELISA assays is as follows: provisional frames are established via frame-shifting, using the pre-experimental mean and cumulative coefficient of variation (CV) from the preceding batch. For batches used >20 days with >20 QC points, permanent frames are constructed by aggregating in-control data accumulated over ≥20 days with ≥20 points to calculate cumulative mean and standard deviation. The provisional and permanent frames constructed by this method identified all 26 extreme outliers across Blood Centers 1 and 9 as out-of-control. Among the 218 general outliers, 10 were classified as normal by the provisional frames, while the remainder were designated as warnings or out-of-control. This method effectively monitors assay stability. Conclusion: Based on the statistical analysis of IQC practices across blood centers of varying scales, combined with the inherent characteristics of ELISA assays and the batch-to-batch instability of reagents/QC materials, it is recommended to reconstruct QC charts upon lot changes. The proposed method—utilizing frame-shifting for provisional frames and establishing permanent frames based on cumulative data—is applicable to blood center laboratories of differing sizes and effectively monitors the stability of the ELISA assay process.

ObjectiveTo observe the clinical efficacy of Tangshen Dihuang decoction in treating diabetic kidney disease （DKD） with liver-kidney Yin deficiency and blood stasis syndrome and its impact on gut microbiota. MethodsA randomized controlled clinical trial was conducted， in which 102 DKD patients with liver-kidney Yin deficiency and blood stasis syndrome were randomly assigned to the Tangshen Dihuang decoction group and the control group. Each group consisted of 51 cases， and the treatment period was 3 months. The primary efficacy indicators included urinary albumin-to-creatinine ratio （UACR）， fasting blood glucose （FBG）， 2-hour postprandial blood glucose （2 hPBG）， glycated hemoglobin （HbA₁C）， serum creatinine （SCr）， blood urea nitrogen （BUN）， angiotensinⅡ （AngⅡ）， serum cystatin C （Cys-C）， urinary N-acetyl-β-D-glucosaminidase （NAG）， urinary β₂-microglobulin （Uβ₂-MB）， traditional Chinese medicine （TCM） symptom scores， and gut microbiota. ResultsAfter treatment， the total response rate in the Tangshen Dihuang decoction was 87.23% （41/47）， which was higher than that （69.57%， 32/46） in the control group （Z=4.30， P<0.05）. After treatment， the TCM symptom scores decreased in both groups （P<0.01） and were lower in the Tangshen Dihuang decoction group than in the control group （P<0.01）. After treatment， the control group showed decreases in UACR， Uβ₂-MG， AngⅡ， and FBG （P<0.05） as well as 2 hPBG and HbA₁C （P<0.01）， and no significant differences in BUN， Cys-C， eGFR， SCr， and NAG. The Tangshen Dihuang decoction group showed increased eGFR （P<0.05）， declined levels of UACR， BUN， Cys-C， Uβ₂-MB， AngⅡ， FBG， 2 hPBG， NAG， and HbA₁C （P<0.01）， and no significant difference in SCr. The Tangshen Dihuang decoction group had lower BUN （P<0.05）， Cys-C （P<0.05）， AngⅡ （P<0.05）， 2 hPBG （P<0.05）， Uβ₂-MG （P<0.01）， and NAG （P<0.01） and higher eGFR level （P<0.05） than the control group. After treatment， the control group showed declines in Shannon， Observed_species， and Chao1 indices （P<0.05）. The samples from both groups showed statistically significant differences in the principal coordinates analysis （PCoA） plot based on Anosim analysis （P<0.05）. After treatment， the Tangshen Dihuang decoction group showed decreased relative abundance of Actinobacteria （P<0.05）. Moreover， the relative abundance of Actinobacteria was significantly lower in the Tangshen Dihuang decoction group than in the control group （P<0.05）. At the genus level， the control group showed decreased relative abundance of Bifidobacterium （P<0.05）， and the Tangshen Dihuang decoction group presented increased relative abundance of Bifidobacterium and Blautia_A （P<0.05）. After treatment， the Tangshen Dihuang decoction group had higher relative abundance of Bifidobacterium than the control group （P<0.01）. ConclusionTangshen Dihuang decoction has a significant therapeutic effect on DKD patients with liver-kidney Yin deficiency and blood stasis syndrome. It can markedly relieve clinical symptoms and reduce proteinuria and postprandial blood glucose by antagonizing the local renin-angiotensin system （RAS） and alleviating gut microbiota dysbiosis.

Vertebral refracture following percutaneous vertebral augmentation (PVA) is commonly seen in elderly patients with osteoporotic thoracolumbar compression fractures (OTLCF). It can lead to recurrent pain, loss of vertebral height, progression of kyphosis, and even neurological dysfunction, significantly impairing patients′ quality of life. Current diagnosis and treatment face multiple challenges, including high misdiagnosis rate, difficulty in choosing between surgical and non-surgical treatment options, lack of standardized surgical protocols, interference from intralesional bone cement during procedures, inadequate stability of internal fixation in osteoporotic bone, and suboptimal compliance of anti-osteoporotic therapy. Establishing a standardized diagnostic and therapeutic framework is urgently needed. To standardize the management process and improve outcomes for vertebral refractures after PVA in elderly OTLCF patients, Spinal Trauma Group of the Orthopedic Branch of Chinese Medical Doctor Association organized experts in the field to develop Guideline for the diagnosis and treatment of vertebral refracture after percutaneous vertebral augmentation in elderly patients with osteoporotic thoracolumbar compression fractures ( version 2025), based on current literature and clinical experience, and adhering to principles of scientific rigor and clinical applicability. A total of 11 recommendations were proposed, encompassing diagnosis, treatment, and rehabilitation of vertebral refracture after PVA in elderly patients with OTLCF, aiming to provide a foundation for a standardized management.

Objective:To compare the efficacy of closed reduction and internal fixation combined with percutaneous kyphoplasty (PKP) and non-operative treatment for intertrochanteric fracture combined with osteoporotic vertebral compression fracture (OVCF) in the elderly.Methods:A retrospective cohort study was conducted to analyze the clinical data of 59 patients with intertrochanteric fracture combined with OVCF admitted to Tianjin Hospital from June 2020 to June 2023, including 16 males and 43 females, aged 66-91 years [(80.2±6.8)years]. The injured vertebral segments included T 10 in 3 patients, T 11 in 9, T 12 in 18, L 1 in 17, L 2 in 8, and L 3 in 4. According to the Genant semi-quantitative classification of vertebral fracture, 42 patients were scaled into grade 1 and 17 into grade 2. Based on the AO classification of intertrochanteric fracture, 33 patients were classified as type A1, 21 type A2, and 5 type A3. All the patients underwent closed reduction and internal fixation for intertrochanteric fractures, among whom 26 patients received PKP after the internal fixation of OVCF (PKP group) and 33 patients received non-surgical treatment after the internal fixation of OVCF (non-surgical group). The healing of the hip incision at 2 weeks after internal fixation and the healing of intertrochanteric fractures at 6 months after surgery were observed in both groups. The visual analogue scale (VAS) for low back pain was compared between the two groups before PKP, immediately after PKP, at 3 months after PKP, and at the last follow-up. The Oswestry disability index (ODI), anterior vertebral height ratio, and Cobb angle of the injured vertebrae were compared between the two groups before PKP, at 3 months after PKP, and at the last follow-up. The Harris hip function score was compared between the two groups at 3 months after internal fixation and at the last follow-up. Cement leakage was observed. The incidence of deep vein thrombosis (DVT) in the lower extremities after internal fixation were compared between the two groups. Results:All the patients were followed up for 10-46 months [(25.5±9.9)months]. The hip incisions of both groups all healed by first intention at 2 weeks after internal fixation, and the intertrochanteric fracture in both groups had bony union at 6 months after surgery. There were no significant differences between the two groups in VAS or ODI before PKP ( P>0.05). Immediately after PKP, at 3 months after PKP, and at the last follow-up, the VAS scores for low back pain were (2.6±0.6)points, (2.4±0.9)points, and (1.5±0.5)points in the PKP group, which were lower than those in the non-surgical group [(8.2±0.8)points, (3.7±1.2)points, and (3.3±0.6)points] ( P<0.01). At 3 months after PKP and at the last follow-up, the ODI values were (21.4±6.9)% and (16.2±6.3)% in the PKP group, which were lower than (38.6±11.6)% and (32.7±12.0)% in the non-surgical group ( P<0.01). The VAS for low back pain and ODI in both groups were gradually improved at each time point after PKP compared with those before PKP ( P<0.05 or 0.01). There were no significant differences in the anterior vertebral height ratio or Cobb angle of the injured vertebrae in the two groups before PKP ( P>0.05). At 3 months after PKP and at the last follow-up, the anterior vertebral height ratio was (79.8±9.6)% and (79.3±9.4)% in the PKP group, which were higher than (73.4±9.3)% and (62.0±10.4)% in the non-surgical group ( P<0.05 or 0.01); the values of the Cobb angle of the injured vertebrae were (12.6±3.6)° and (12.0±3.3)°in the PKP group, which were lower than (15.5±2.6)° and (20.4±4.9)° in the non-surgical group ( P<0.01). There were no significant differences in the anterior vertebral height ratio and Cobb angle of the injured vertebrae in the PKP group before PKP and at each time point after PKP ( P>0.05) while in the non-surgical group, the anterior vertebral height ratio at each time point after PKP was lower than that before PKP and the Cobb angle of the injured vertebrae was increased compared with that before PKP ( P<0.01). At 3 months after internal fixation and at the last follow-up, the Harris hip function scores in the PKP group were (76.4±3.4)points and (87.7±4.5)points, which were higher than (57.0±6.8)points and (76.3±8.9)points in the non-surgical group ( P<0.01). The Harris hip function scores in both groups were improved at the last follow-up, compared with those at 3 months after internal fixation. Five patients had cement leakage in the PKP group, all of which were lateral leakage.There was no occurrence of radiating pain in the lower extremities. The incidence of DVT at 1 month after internal fixation was 19.2% (5/26) in the PKP group, which was lower than 57.6% (19/33) in the non-surgical group ( P<0.01). Conclusion:Compared with non-operative treatment after the closed reduction and internal fixation, PKP after internal fixation can significantly relieve low back pain in the early stage, improve the functional restoration of the vertebral column, maintain vertebral height, prevent kyphosis, promote the recovery of the hip joint function, and reduce the occurrence of DVT in the lower extremities in the treatment of intertrochanteric fracture combined with OVCF.

ObjectiveTo explore the distribution pattern of tongue image characteristics in patients with glucolipid metabolic disorders and its main syndromes. MethodsA total of 841 patients with glucolipid metabolic disorders （disease group）， and 380 healthy subjects （control group） were included. The disease group was classified into three syndrome types： 283 cases of liver depression and spleen deficiency syndrome， 311 cases of phlegm-dampness obstruction syndrome， and 247 cases of qi stagnation and blood stasis syndrome. Tongue image data were collected using the TFDA-1 Tongue Diagnosis Instrument， and the TDAS V3.0 software was used to analyze the color， texture， and morphological features of the tongue body （TB） and tongue coating （TC） in patents with different syndromes of disease group （including lightness （L）， red-green axis （a）， yellow-blue axis （b）， luminance （Y）， difference between red signal and brightness （Cr）， difference between blue signal and brightness （Cb）， contrast （CON）， angular second moment （ASM）， entropy （ENT）， mean value （MEAN）， tongue coating area/tongue surface area （perAll）， and tongue coating area/non-coated area （perPart））. Logistic regression analysis was conducted to identify influencing factors for different syndrome types of glucolipid metabolic disorders. ResultsThe tongue body indicators TB-L， TB-Y， and TB-Cb in the disease group were significantly higher than those in the control group， while TB-a， TB-b， and TB-Cr were significantly lower. The tongue coating indicators TC-L， TC-Y， TC-Cb， perAll， and perPart in the disease group were significantly higher than those in the control group， while TC-a， TC-b， and TC-Cr were significantly lower （P＜0.05）. Comparing with the different syndromes in disease group， the TB-L and TB-Y of the liver depression and spleen deficiency syndrome， and the phlegm-damp obstruction syndrome were higher than those of the qi stagnation and blood stasis syndrome； the TB-a and TB-Cr of the phlegm-damp obstruction syndrome were lower than those of the qi stagnation and blood stasis syndrome； the perAll of the phlegm-damp obstruction syndrome was higher than that of the qi stagnation and blood stasis syndrome （P＜0.05）. In the analysis of the morphological characteristics of tongue signs， more spotted tongue in disease group compared with control group， more teeth-marked tongue in liver depression and spleen deficiency syndrome than the other two syndromes， more greasy coating in phlegm-damp obstruction syndrome， and more stasis spots of tongue in qi stagnation and blood stasis syndrome （P＜0.05）. Logistic regression analysis identified that greasy coating， spotted tongue， stasis spots of tongue， tooth-marked tongue， perAll， and TB-Cb are the influencing factors of liver depression and spleen deficiency syndrome； greasy coating， tooth-marked tongue， TC-Cb， and TC-Cr are the influencing factors of phlegm-damp obstruction syndrome； cracked tongue， stasis spots of tongue， tooth-marked tongue， and TB-Y are the influencing factors of qi stagnation and blood stasis syndrome （P＜0.05）. ConclusionCompared to healthy individuals， patients with glycolipid metabolic disorder have darker tongue color and thicker， greasy tongue coating. Glycolipid metabolic disorder patients of liver depression and spleen deficiency syndrome exhibit a reddish tongue with finer textures and more tooth marks； patients of phlegm-damp obstruction syndrome have lighter tongue coating with a coarser texture and a higher prevalence of greasy coating； patients of qi stagnation and blood stasis syndrome display lower tongue brightness with a higher prevalence of blood stasis spots.

Animal experiments are an essential component of life sciences and medical research. However, the external validity and reliability of individual animal studies are frequently challenged by inherent limitations such as small sample sizes, high design heterogeneity, and poor reproducibility, which impede the effective translation of research findings into clinical practice. Systematic reviews and meta-analysis represent a key methodology for integrating existing evidence and enhancing the robustness of conclusions. Currently, however, the application of systematic reviews and meta-analysis in the field of animal experiments lacks standardized guidelines for their conduct and reporting, resulting in inconsistent quality and, to some extent, diminishing their evidence value. To address this issue, this paper aims to systematically delineate the reporting process for systematic reviews and meta-analysis of animal experiments and to propose a set of standardized recommendations that are both scientific and practical. The article's scope encompasses the entire process, from the preliminary preparatory phase [including formulating the population， intervention， comparison and outcome （PICO） question, assessing feasibility, and protocol pre-registration] to the key writing points for each section of the main report. In the core methods section, the paper elaborates on how to implement literature searches, establish eligibility criteria, perform data extraction, and assess the risk of bias, based on the Preferred Reporting Items for Systematic Reviews and Meta-analysis （PRISMA) statement, in conjunction with relevant guidelines and tools such as Animal Research： Reporting of in Vivo Experiments （ARRIVE) and a risk of bias assessment tool developed by the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE). For the presentation of results, strategies are proposed for clear and transparent display using flow diagrams and tables of characteristics. The discussion section places particular emphasis on how to scientifically interpret pooled effects, thoroughly analyze sources of heterogeneity, evaluate the impact of publication bias, and cautiously discuss the validity and limitations of extrapolating findings from animal studies to clinical settings. Furthermore, this paper recommends adopting the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology to comprehensively grade the quality of evidence. Through a modular analysis of the entire reporting process, this paper aims to provide researchers in the field with a clear and practical guide, thereby promoting the standardized development of systematic reviews and meta-analysis of animal experiments and enhancing their application value in scientific decision-making and translational medicine.

ObjectiveTo analyze the current status of per⁃ and polyfluoroalkyl substances (PFASs) contamination in animal⁃derived foods in Shanghai and to assess the risk of dietary exposure among local residents, thereby providing a scientific basis for future dietary safety and risk management. MethodsA total of 300 commonly consumed animal⁃derived food samples were collected in Shanghai in 2023 and tested for 17 types of PFASs. Based on local dietary consumption data, the weekly exposure intake (EWI) of four representative PFASs was calculated using the exposure assessment model recommended by Food and Agriculture Organization (FAO) and the World Health Organization (WHO). The calculated EWI was compared with the tolerable weekly intake (TWI) set by the European Food Safety Authority (EFSA) to assess the health risks associated with dietary intake of PFASs. ResultsThe predominant PFASs detected in aquatic products were PFUnDA (98.67%), PFTrDA (98.00%), and PFOS (95.33%), with PFUnDA having the highest median mass fraction (0.378 ng·g^-1). In meat samples, PFBA (54.17%), PFOA (20.83%), and PFOS (18.33%) were mainly detected, with PFBA showing the highest median mass fraction (0.027 ng·g^-1). In egg samples, the most frequently detected compounds were PFBA (90.00%), PFOA (63.33%), PFOS (50.00%), PFDA (50.00%), PFNA (50.00%), and PFHxDA (50.00%), with PFBA again having the highest median mass fraction (0.068 ng·g^-1). The median mass fractions of the four key PFASs (PFOA, PFOS, PFNA, and PFHxS) in aquatic products were significantly higher than those in meat products and eggs (all P<0.001), and there were statistically significant differences in the median mass fractions of the four PFASs among different types of aquatic products (all P<0.05). The EWI of the four PFASs was 2.970 ng·kg^-1 for the mean consumption group and 6.676 ng·kg^-1 for the high consumption group (P₉₅), with females having higher EWI values than males. ConclusionPFOS, PFOA, and PFBA are the major PFAS contaminants in animal⁃derived foods consumed by Shanghai residents, with aquatic products having the highest levels of contamination. The EWIs of four PFASs among Shanghai residents did not exceed EFSA’s recommended TWI at average consumption levels. However, the EWIs for high⁃consumption populations exceeded the EFSA⁃recommended TWI, posing potential health risks to these populations. Aquatic products contribute the most to dietary PFAS exposure. It is necessary to strengthen PFAS monitoring in aquatic products and conduct targeted risk assessments for high⁃consumption groups.

ObjectiveTo analyze the epidemiological and clinical characteristics of pertussis in Baoshan District, Shanghai from 2017 to 2024, so as to provide an evidence-based reference for optimizing prevention and control strategies. MethodsData on pertussis cases were collected from the China Disease Prevention and Control Information System, Shanghai Integrated Management and Immunization Service Information System, and follow-up epidemiological investigations. Descriptive epidemiological analyses were performed to analyze the epidemiological characteristics, clinical manifestations, and vaccine effectiveness. Joinpoint regression analyses were used to examine the temporal trends in incidence rates, and a Poisson model was constructed for spatiotemporal scan analyses. ResultsA total of 1 634 pertussis cases were reported in Baoshan District from 2017 to 2024, with a male-to-female ratio of 1.08∶1. More cases were observed in males than in females, with the age ranged from 20 days to 81 years. Among them, 59.92% were in the 6‒<11 years age group, and 63.34% were students. Low-level sporadic incidence persisted during 2017‒2023, followed by a sharp increase in 2024 (71.37/100 000). Starting in January 2024, the incidence rate showed an upward trend, peaking in May before declining. The majority of cases occurred between April and June. The trend in reported pertussis incidence rates in Baoshan District from 2017 to 2023 showed no statistically significant change (APC=10.039%, t=2.586, P=0.150). Incidence rate rose from January 2024, peaked in May (APC=133.641%, t=3.841, P=0.006), then declined significantly (APC=-47.816%, t=2.586, P<0.001). The 12 subdistricts of Baoshan District were divided into low, medium, and high population density areas, with an average annual reported incidence rate of 6.09/100 000, 8.19/100 000 and 11.96/100 000, respectively. The reported incidence rate increased with an increase in population density. Spatiotemporal scan analyses showed that cases clustered in the southwest and northeast of Baoshan District. Epidemiological follow-up investigations of 1 520 cases revealed that the main clinical symptoms were cough (97.63%) and sputum production (41.58%), and 98.13% of the cases were confirmed by positive nucleic-acid test results. Among the 1 475 cases with immunization records, 83.53% had completed the four-dose pertussis vaccine before onset. The complication incidence rates, from high to low, were in the 0-dose vaccination group, 1‒3-dose vaccination group and 4-dose vaccination group. The duration of cough, from long to short, was observed in the the 0-dose vaccination group, 1‒3-dose vaccination group and 4-dose vaccination group, correspondingly. ConclusionIt is recommended to improve the pertussis surveillance system in medical institutions and establish an active monitoring network, prioritizing deployment in school settings and areas with high population density. Enhancing diphtheria-tetanus-pertussis (DTP) vaccination coverage among 6-year-old children and further optimizing the pertussis immunization strategies are essential to prevent and reduce the risk of pertussis among school-aged children.

Objective: To investigate the mechanism by which icariin ( ICA) inhibits the invasion and metastasis of human triple-negative breast cancer ( TNBC) cells via downregulation of the transforming growth factor-β/ Smad ( TGF-β/ Smad) signaling pathway． Methods: TNBC cells ( MDA-MB-231 and MDA-MB-468) were cultured in vitro and divided into four groups: an experimental group treated with 15 μmol / L ICA; a model group treated with 10 μmol / L TGF-β receptor inhibitor LY2109761; a combination group ( LY2109761 + ICA) treated with both 15 μmol / L ICA and 10 μmol / L LY2109761; and a control group．Cell proliferation，migration，and invasion were as- sessed using CCK-8，colony formation，5-ethynyl-2 '-deoxyuridine ( EdU) ，wound healing，and Transwell assays． The expression levels of epithelial-mesenchymal transition ( EMT) -related proteins，as well as TGF-β1，Smad2， and phosphorylated Smad2 ( P-Smad2) were detected by immunofluorescence and Western blot． Results: CCK-8 results showed that cell proliferation decreased gradually with increasing concentrations of ICA ( P＜0. 05) ．Colony formation and EdU assays indicated significantly inhibited proliferation in the ICA-treated group compared to the control ( P＜0. 05) ．Wound healing and Transwell assays demonstrated reduced migration and invasion capabilities in the experimental group relative to the control ( P＜0. 05) ．Compared to the model group，the LY2109761 + ICA group exhibited further suppression of invasion ( P＜0. 05) ．Immunofluorescence revealed decreased Vimentin ex- pression in the experimental group ( P＜0. 05) ，with an even more pronounced reduction in the LY2109761 + ICA group ( P＜0. 01) ．Western blot analysis showed that the protein levels of N-cadherin，matrix metalloproteinase-9( MMP9) ，Vimentin，TGF-β1，Smad2，and P-Smad2 were downregulated in the experimental group compared to the control ( P＜0. 05) ．These proteins were further suppressed in the LY2109761 + ICA group compared to the model group ( P＜0. 05) ． Conclusion ICA inhibits TNBC cells proliferation，invasion，metastasis，and EMT by downregulating the TGF-β/ Smad signaling pathway．

Background Industrial emissions are a well-established major source of urban fine particulate matter (PM_2.5) and associated heavy metals. To improve local air quality, Shanghai No. 1 Iron and Steel Plant in Baoshan District was entirely relocated, with all production lines successively shut down in 2018. Objective To evaluate the trends in PM_2.5 and three heavy metal concentrations - chromium (Cr), mercury (Hg), and thallium (Tl) —in the local atmosphere pre- and post- relocation of the steel plant. Methods Taking the steel plant relocation in 2019 as the intervention cutoff point, this study was divided into two phases: pre-intervention (January 2017 to December 2018) and post-intervention (January 2019 to December 2021). Monthly mean pollutant concentrations were used to construct an interrupted time series (ITS) model, followed by segmented linear regression to assess the pre- and post-intervention trends in ambient PM_2.5 and three heavy metals surrounding thesteel plant. Results The ITS regression analysis revealed that the change in PM_2.5 concentration (b₂) after the intervention was −7.16 μg·m⁻³, while the changes in Cr, Hg, and Tl concentrations (b₂) were −0.46, −0.03, and −0.06 ng·m⁻³, respectively. Prior to the intervention, PM_2.5 mass concentrations exhibited a temporal decline with a slope of b₁ = –0.69 (P<0.05); seasonal adjustment further strengthened the overall significance of the model. Before the intervention, the concentration of Cr increased over time, with a slope of b₁=0.12 (P<0.05). After the intervention, the concentration of Cr showed a gradual downward trend over time, with a slope (b₁ + b₃) of −0.04, and significant seasonal variations were observed. The concentration of Hg decreased over time before the intervention, with a slope of b₁=−0.0029 (P<0.05). After the intervention, the slope was −0.0003, showing a further slow decline in Hg concentration over time. However, no significant seasonal trend was observed for Hg. The mass concentration of Tl decreased after the intervention, and the difference before and after the intervention was statistically significant (P<0.05). PM_2.5, Cr, and Tl better fit to the seasonal model, whereas Hg showed a better fit to the non-seasonal model. Conclusion The steel plant relocation intervention has markedly improved local air quality.