1.Association between mental health and muscle strength among Chinese adolescents aged 13-18
Chinese Journal of School Health 2025;46(9):1232-1236
		                        		
		                        			Objective:
		                        			To explore the association between mental health and muscle strength among Chinese adolescents aged  13- 18, providing a theoretical foundation and intervention strategies for mental health promotion.
		                        		
		                        			Methods:
		                        			Data were obtained from the 2019 Chinese National Survey on Students  Constitution and Health, including 98 631 Chinese adolescents aged  13- 18. Psychological distress was assessed by using the Kessler Psychological Distress Scale (K10), and mental well being was measured with the Warwick-Edinburgh Mental Well being Scale (WEMWBS). Based on the gender  and age specific  Z scores of various test items [grip strength, standing long jump, pull ups (for males), and sit ups (for females)], muscle strength index (MSI) was constructed to evaluate the comprehensive level of muscle strength in adolescents. According to the Dual factor Model (DFM) of mental health, participants were categorized into four groups:troubled, symptomatic but content, vulnerable, and complete mental health. Gender differences were analyzed by using  Chi-square tests, trends were tested with Cochran-Armitage tests, and multinomial Logistic regression models were applied to assess associations between muscle strength and mental health among adolescents.
		                        		
		                        			Results:
		                        			In 2019, 37.4% of Chinese adolescents aged 13-18 were reported of high mental distress, and 59.9% were reported of low mental well being. Boys had significantly lower rates of high mental distress (35.3%) and low mental well being (55.6%) compared to girls (39.4%, 64.3%), and the differences were of statistical significance ( χ 2=176.13, 780.42, both  P <0.05). In 2019, the rate of complete mental health among adolescents showed a downward trend with increasing age ( χ 2 trend = 258.47) and a gradual upward trend with increasing muscle strength levels ( χ 2 trend =123.14),and both boys and girls exhibited similar trends ( χ 2 trend =103.83, 168.46;  57.00 , 67.34) (all  P <0.05). The results of the unordered multiclass Logistic regression model showed that after controlling for confounding factors such as age and gender, when the completely pathological group as a reference, for every 1 unit increase in MSI in adolescents, the likelihood of being in a completely mental health state increased by 29% ( OR = 1.29); for every unit increase in the  Z-score for pull ups, the likelihood of being in a completely mental health state increased by 6% ( OR =1.06) among boys; for every 1 unit increase in sit up  Z score, the likelihood of being in a completely mental health state increased by 19% ( OR =1.19) among girls (all  P <0.05).
		                        		
		                        			Conclusions
		                        			The mental health status of Chinese adolescents is not good enough. Muscle strength is positively associated with mental health.
		                        		
		                        		
		                        		
		                        	
2.Evolution and development of mental health policies for children and adolescents in China
Chinese Journal of School Health 2025;46(9):1246-1251
		                        		
		                        			Objective:
		                        			To systematically review the development and changes in mental health policies within the National Outline for Children s Development in China from 1992 to 2030, providing a reference basis for future formulation of mental health policies among children and adolescent in China.
		                        		
		                        			Methods:
		                        			Based on the four editions of the National Outline for Children s Development in China across different periods from 1992 to 2030, word frequency analysis was used to reveal shifts in policy priorities, and an internationally recognized framework for adolescent health policy analysis was applied to conduct a textual review.
		                        		
		                        			Results:
		                        			Word frequency analysis revealed that the term "psychological" appeared 6 times in the National Outline for Children s Development in China (2001-2010) but increased to 20 times in the National Outline for Children s Development in China (2021-2030) (abbreviated as the National Outline of 2021), while the term "health" rose from 4 times in the National Outline for Children s  Development Plan in China in the 1990s to 68 times in the National Outline of 2021. The scope of mental health policy interventions expanded to encompass five key areas:health, safety, education, welfare and legal protection. Textual analysis highlighted that the policies of the National Outline for Children s Development in China were demand driven, prioritized vulnerable groups and continuously broadened their coverage, emphasizing sustainability and appropriateness, and monitoring/evaluation mechanisms. By 2023, 42.3% of primary schools and 64.8% of secondary schools employed full time mental health education teachers. However, the National Outline for Children s Development in China lacked direct evidence of children and adolescents participation in policy formulation, and publicly available mental health data disaggregated by age and gender remained limited.
		                        		
		                        			Conclusion
		                        			Mental health policies of children and adolescents in China have evolved from nonexistence to gradual refinement, yet institutionalized channels for youth involvement in policy development and evaluation remain insufficient, and transparency in age  and gender specific mental health data needs improvement.
		                        		
		                        		
		                        		
		                        	
3.Distribution characteristics, source apportionment, and health risk assessment of metals and metalloids in PM2.5 in a southern city in 2019
Yaxin QU ; Suli HUANG ; Chao WANG ; Jie JIANG ; Jiajia JI ; Daokui FANG ; Shaohua XIE ; Xiaoheng LI ; Ning LIU
Journal of Environmental and Occupational Medicine 2025;42(2):196-204
		                        		
		                        			
		                        			Background Metals and metalloids in fine particulate matter (PM2.5) may cause damage to the respiratory and circulatory systems of the human body, and long-term exposure is prone to causing chronic poisoning, cancer, and other adverse effects. Objective To assess the distribution characteristics of metals and metalloids in outdoor PM2.5 in a southern city of China, conduct source apportionment, and evaluate the associated health risks, thereby providing theoretical support for further pollution control measures. Methods PM2.5 samples were collected in districts A, B, and C of a southern China city, and the concentrations of 17 metals and metalloids were detected by inductively coupled plasma-mass spectrometry (ICP-MS). Pollution sources were assessed through enrichment factor and principal components analysis, and the main pollution sources were quantified using absolute principal component scores-multivariate linear regression (APCS-MLR). Health risks were evaluated based on the Technical guide for environmental health risk assessment of chemical exposure (WS/T777—2021). Results The ambient air PM2.5 concentrations in the city were higher in winter and spring, and lower in summer and autumn. The annual average concentrations of ambient PM2.5 in districts A, B, and C were 36.7, 31.9, and 24.4 μg·m−3, respectively. The ambient PM2.5 levels in districts B and C were below the second-grade limit set by the Ambient air quality standards (GB 3095—2012). The enrichment factors of cadmium (Cd), aluminum (Al), and antimony (Sb) were greater than 10, those of copper (Cu), lead (Pb), arsenic (As), nickel (Ni), mercury (Hg), and molybdenum (Mo) fell between 1 and 10, and those of manganese (Mn), vanadium (V), chromium (Cr), cobalt (Co), barium (Ba), beryllium (Be), and uranium (U) were below or equal to 1. The comprehensive evaluation of source analysis showed that the main pollution sources in districts A and C and the whole city were coal-burning. In district B, the main pollution source was also coal combustion, followed by industrial process sources and dust sources. The carcinogenic risks of As and Cr were between 1×10−6 and 1×10−4. However, the hazard quotients for 15 metals and metalloids in terms of non-carcinogenic risk were below 1. Conclusion Cr and As in the atmospheric PM2.5 of the city present a certain risk of cancer and should be paid attention to. In addition, preventive control measures should be taken against relevant pollution sources such as industrial emission, dust, and coal burning.
		                        		
		                        		
		                        		
		                        	
4.Changes of retinal nerve fiber layer thickness, retinal thickness and blood flow density in different stages of diabetic retinopathy patients
Shujun ZHANG ; Shuai HUANG ; Jiajia LI ; Songbo PEI ; Yuhong LI
International Eye Science 2025;25(5):714-717
		                        		
		                        			
		                        			 AIM: To investigate the changes of retinal nerve fiber layer(RNFL)thickness, retinal thickness and blood flow density in different stages of diabetic retinopathy(DR)patients based on optical coherence tomography angiography(OCTA).METHODS: A retrospective analysis was conducted on 382 patients(382 eyes)diagnosed with DR in our hospital from February 2023 to February 2024. According to the staging criteria, the patients were divided into mild group(n=121), moderate group(n=133), severe group(n=72), and proliferative group(n=56). The general clinical data of the four groups of patients was compared; OCTA was used to scan and collect data from all patients, and the RNFL thickness, retinal thickness, and blood flow density were compared among the four groups of patients.RESULTS: There was no statistically significant difference in age, gender, hypertension, chronic kidney disease, and random blood glucose among patients in the mild, moderate, severe, and proliferative groups(all P>0.05). As the stage of DR worsened, the duration of the disease gradually prolonged(P<0.05). The thickness of the RNFL(superior, inferior, temporal, nasal, and average thickness)and retinal thickness significantly increased with the severity of DR(all P<0.001); however, there was no statistically significant difference in inferior RNFL thickness between the moderate and mild groups(P>0.05). The blood flow density in the superficial and deep retinal layers, as well as in the choroidal capillary layer, significantly decreased with the progression of DR(all P<0.05). Nevertheless, there was no statistically significant difference in superficial retinal blood flow density between the moderate and severe groups(P>0.05).CONCLUSION: OCTA can accurately observe the changes in RNFL thickness, retinal thickness, and blood flow density in patients with DR at different stages, which can serve as sensitive indicators for monitoring DR progression. 
		                        		
		                        		
		                        		
		                        	
5.A randomized controlled study of anti-inflammatory effects of different non-steroidal anti-inflammatory drugs in the postoperative stage of phacoemulsification combined with intraocular lens implantation surgery
Jiajia GE ; Qing LIU ; Jinyan ZHOU ; Xiaona SHAN ; Yusen HUANG
Chinese Journal of Experimental Ophthalmology 2024;42(3):256-263
		                        		
		                        			
		                        			Objective:To explore the anti-inflammatory effect and safety of two non-steroidal anti-inflammatory drugs in the phacoemulsification combined with intraocular lens (IOL) implantation.Methods:A randomized, double-blind, clinical trial was conducted.A total of 90 age-related cataract patients (90 eyes) who were diagnosed in Qingdao Eye Hospital Affiliated to Shandong First Medical University were enrolled from October 2020 to February 2021.The patients were randomized to diclofenac sodium group and bromofenac sodium group by random number table method, with 45 cases (45 eyes) in each group.All patients underwent phacoemulsification combined with IOL implantation, and 0.1% diclofenac sodium eye drops (preservative-free), 4 times a day, and 0.1% pramiphene eye drops, 2 times a day were applied in the perioperative period.The duration of continuous medication treatment and follow-up time were 6 weeks.The subjective symptoms of the patients were scored before and after surgery.The amount of tear fluid secretion was detected by Schirmer I test, and the tear film breakup time was recorded with the Oculus dry eye analyzer.Corneal fluorescein staining was observed under a slit lamp microscope with cobalt blue light.Anterior chamber flash was measured by slit-lamp biomicroscopy.The thickness of central macular area and the presence of macular cystoid edema was measured by optical coherence tomography.Visual acuity, noncontact intraocular pressure (IOP) and the drug safety were examined and evaluated.This study adhered to the Declaration of Helsinki and was approved by the Ethics Committee of Qingdao Eye Hospital (No.[2020]60).All patients were informed about the surgery and postoperative medication and signed the informed consent form.Results:All subjects had no intraoperative complications, and completed treatment and follow-up as required.The preoperative, 1-day postoperative, 1-week postoperative, 6-week postoperative subjective symptom scores were (0.47±0.73), (0.56±0.62), (0.33±0.48), and (0.51±0.66) points in the diclofenac group, and (0.47±0.51), (0.75±0.61), (0.64±0.65), and (0.78±0.77) points in the bromfenac group.There were statistically significant differences in the subjective symptom scores at different time points between the two groups ( Fgroup=5.001, P=0.028; Ftime=2.920, P=0.035), and the subjective symptom scores of diclofenac sodium group were significantly lower than those of bromofenac sodium group (all at P<0.05).The preoperative, 1-week postoperative, 6-week postoperative tear secretion volume were (5.87±2.37), (6.07±2.53), and (6.29±0.25) mm in diclofenac sodium group, and (7.36±2.74), (6.29±3.46), and (5.80±2.76) mm in bromofenac sodium group.There was statistically significant difference in the tear secretion volume between the two groups before surgery ( F=6.910, P=0.012), but there was no significant difference on postoperative weeks 1 and 6 ( F=1.121, 0.772; P=0.729, 0.384).The preoperative, 1-week postoperative, 6-week postoperative non-invasive tear break-up time (NIBUT) were (8.00±6.28), (6.68±5.24), and (6.17±5.00) seconds in diclofenac sodium group, and (6.40±5.28), (4.50±2.46), and (5.39±5.39) seconds in bromofenac sodium group.There was no significant difference in NIBUT between the two groups ( Fgroup=3.415, P=0.068).There was significant difference in NIBUT within groups among different time points ( Ftime=4.358, P=0.020).The 1-day postoperative, 1-week postoperative, 6-week postoperative corneal epithelial staining score were (1.40±0.81), (0.13±0.34), (0.00±0.00) points in diclofenac sodium group, and (1.38±0.89), (0.22±0.47), and (0.00±0.00) points in bromofenac sodium group.There was no statistically significant difference in the corneal epithelial staining score between the two groups after surgery ( Fgroup=0.110, P=0.741).There were statistically significant differences in corneal epithelial staining scores within groups among different time points ( Ftime=175.054, P<0.01).The 1-day postoperative, 1-week postoperative, 6-week postoperative anterior chamber flare classification were 1.13±0.51, 0.13±0.34, and 0.00±0.00 in diclofenac sodium group, and 1.02±0.34, 0.16±0.37, and 0.00±0.00 in bromofenac sodium group.There was no significant difference in the overall anterior chamber flash between the two groups ( Fgroup=0.045, P=0.507).There were statistically significant differences in anterior chamber flash within groups among different time points ( Ftime=322.331, P<0.001).There was no significant difference in the preoperative and 6-week postoperative macular fovea thickness between both groups ( t=-0.221, -0.374; both at P>0.05).The incidence of macular cystoid edema 6 weeks after operation was 0% in both groups.Subjects tolerated the two tested drugs well.Eight adverse events occurred in this study, all of which were mild postoperative IOP elevation, including 3 in diclofenac sodium group with an incidence of 6.67% and 5 in bromofenac group with an incidence of 11.1%.IOP returned to normal in all the patients 1 week after stopping the use of drug. Conclusions:Two nonsteroidal anti-inflammatory drugs are safe and effective for anti-inflammatory treatment after cataract phacoemulsification combined with IOL implantation.The new diclofenac sodium eye drops are more comfortable than bromfenac sodium eye drops.
		                        		
		                        		
		                        		
		                        	
6.Prevalence of comorbidity of spinal curvature abnormality and malnutrition among primary and middle school students in Tianjin in 2023
Chinese Journal of School Health 2024;45(8):1171-1175
		                        		
		                        			Objective:
		                        			To analyze the prevalence of comorbidity of spinal curvature abnormality and malnutrition among primary and secondary school students aged 10-18 years in Tianjin in 2023, so as to provide scientific basis for the combined prevention of common diseases and multiple diseases among students and the construction of school health system.
		                        		
		                        			Methods:
		                        			In September to October 2023, 31 884 primary and secondary school students aged 10 to 18 years in Tianjin were selected using stratified cluster random sampling. Abnormal spinal curvature in children and adolescents was assessed by Sereening of Spinal Curvature Abnormality of Children and Adolescents, while stunting, wasting, overweight, and obesity were determined according to the Screening for Malnutrition among Schoolage Children and Adolescents and Screening for Overweight and Obesity among Schoolage Children and Adolescents. The χ2 test was used to compare betweengroup differences in coprevalence, and multiple Logistic regression models were used to analyze the risk of different comorbidity types in different clusters.
		                        		
		                        			Results:
		                        			The coprevalence of spinal curvature abnormality and malnutrition among primary and secondary school students in Tianjin was 1.6%, which was higher for girls than boys (1.8%, 1.4%), higher (2.5%) for senior high schools than for junior high schools and elementary schools (2.0%, 0.5%), and higher in rural than in urban areas (2.1%, 1.1%) (χ2=9.45, 141.92, 46.94, P<0.05). Multiple Logistic regression models showed that junior high school girls had a higher risk of incorrect posture comorbid with stunting and wasting (OR=4.52, 95%CI=1.84-11.06) and incorrect posture comorbid with overweight and obesity (OR=2.67, 95%CI=1.74-4.10) than boys, and that scoliosis/sagittal spinal abnormality comorbid with stunting and wasting (OR=0.10, 95%CI=0.02-0.44) risk was lower than that of boys, senior high school girls had a lower risk of scoliosis/sagittal spinal abnormality comorbid with overweight and obesity (OR=0.27, 95%CI=0.11-0.66) (P<0.05).
		                        		
		                        			Conclusions
		                        			The coprevalence of spinal curvature abnormality and malnutrition is specific among primary and secondary school students in Tianjin, and the comorbidity type varies by gender and education stage. There is a need to increase prevention and control of spinal curvature abnormalities in school health working, intensive screening of key populations, and timely intervention.
		                        		
		                        		
		                        		
		                        	
7.Application Situation on PI3Kδ Inhibitors in B-cell Lymphoma
Fanli ZHENG ; Yanan ZHENG ; Lili HUANG ; Chenjun SHEN ; Jun LU ; Jiajia YING ; Siyue LOU
Chinese Journal of Modern Applied Pharmacy 2024;41(6):847-858
		                        		
		                        			
		                        			PI3K/AKT/mTOR signaling pathway plays a crucial role in cell proliferation, survival, differentiation, motility and intracellular transport. PI3Kδ, an isoform of PI3K, is highly expressed in B lymphocytes and is involved in the malignant progression of B-cell lymphoma. Thus, PI3Kδ has emerged as an attractive target for the development of anti-B-cell lymphoma drugs. Currently, there are several PI3Kδ inhibitors approved by the FDA for the treatment of B-cell lymphoma, each with its own characteristics, but also with varying degrees of adverse effects in clinical practice. Due to the complexity and diversity of the pathogenesis of B-cell lymphoma, single-target PI3Kδ inhibitors often have limited efficacy and are prone to drug resistance, and need to be combined with chemotherapy or other targeted drugs to enhance their efficacy. The future trend is to design novel inhibitors with higher efficacy and lower toxicity or to develop novel combination regimens with other chemotherapy, radiotherapy, and target drugs to acquire better anti-tumor effects with reduced adverse effects. This review summarizes the PI3Kδ inhibitors that have been approved for the treatment of B-cell lymphoma or are still in clinical trials, mainly focusing on their characteristics, adverse effects and combination regimens.
		                        		
		                        		
		                        		
		                        	
8.Construction of an evaluation index system for emergency response competency of"Internet+"nurses
Nanxing HUANG ; Xiaju HU ; Yunqiu CHE ; Jiajia LIU ; Chaozhu HE
Chinese Journal of Nursing 2024;59(11):1368-1375
		                        		
		                        			
		                        			Objective To establish a scientifically rigorous,standardized,and comprehensive evaluation index system for the emergency response competency of'Internet+'nurses,and to provide references for the access,training and assessment of'Internet+'nurses.Methods Between November 2022 and July 2023,a draft of the evaluation index system was developed based on theoretical analysis,literature reviews and semi-structured interviews.Delphi expert consultation and analytic hierarchy process were used to determine the evaluation index system for emergency response competence of'Internet+'nurses.Results The response rates of 2 rounds were 90.48%and 100%;the opinion rates were 63.16%and 10.53%;the authority coefficients of the experts were 0.855 and 0.850;the Kendall's coefficients of concordance were 0.175 and 0.182.Finally,the evaluation index system for emergency response competency of'Internet+'nurses was formed,which consists of 4 first-level indexes(including prevention capacity,preparedness capacity,response capacity and recovery capacity),13 second-level indexes and 40 third-level indexes.Conclusion The evaluation index system for the emergency response competency of'Internet+'nurses is highly scientific and practical,which has guiding significance for the access,training and assessment of'Internet+'nurses.
		                        		
		                        		
		                        		
		                        	
9.Diagnostic value of multimodal ultrasonography for thyroid nodules in thyroid imaging reporting and data system categories 3 to 5
Ruijuan HUANG ; Shuzhen CONG ; Zhenyi LIN ; Yanyan LIANG ; Jiajia LEI
Chinese Journal of Radiological Health 2024;33(3):346-352
		                        		
		                        			
		                        			Objective To assess the value of multimodal ultrasonography for diagnosing thyroid nodules—atypia of undetermined significance (AUS) of thyroid imaging reporting and data system (TI-RADS) categories 3 to 5. Methods A total of 90 AUS thyroid nodules in TI-RADS 3-5 categories from 88 patients underwent conventional ultrasonography, ultrasound elastography, superb microvascular imaging, and multimodal ultrasonography at the same time. With fine needle aspiration biopsy results as the gold standard, the methods were compared in terms of the sensitivity, specificity, accuracy, false positive rate (FPR), false negative rate (FNR), and area under the receiver operating characteristic curve (AUC) for diagnosing thyroid nodules. Results There were no significant differences between patients with benign and those with malignant thyroid nodules in terms of sex, age, and nodule locations (all P > 0.05), but the proportion of thyroid nodules ≤ 1 cm in diameter was significantly higher for malignant thyroid nodules than for benign thyroid nodules (χ2=9.610, P=0.002). Compared with benign nodules, malignant nodules were significantly more frequent to have low-level echoes or very low-level echoes, a blurred margin, a vertical diameter/horizontal diameter ratio of > 1, and microcalcifications or no calcifications (all P < 0.05). An ultrasound elastography score of ≥ 3 and type III vascularity on superb microvascular imaging indicated a higher possibility of malignant thyroid nodules (both P < 0.001). The multivariable logistic regression analysis showed that the size, echogenicity, margin, and vertical diameter/horizontal diameter ratio, and superb microvascular imaging type of thyroid nodules were not significant markers for benign or malignant thyroid nodules (all P > 0.05), while microcalcifications/no calcifications and an ultrasound elastography score of ≥ 3 were independent risk factors for malignant AUS nodules (both P < 0.05). The diagnostic sensitivity, specificity, accuracy, FPR, and FNR of conventional ultrasonography for AUS nodules were 91.30%, 71.40%, 62.70%, 28.60%, and 8.70%, respectively; the values for ultrasound elastography were 85.50%, 66.70%, 52.20%, 33.30%, and 14.50%, respectively; the values for superb microvascular imaging were 66.70%, 76.20%, 42.90%, 23.80%, and 33.30%, respectively; and the values for multimodal ultrasonography were 75.20%, 92.50%, 67.70%, 24.80%, and 7.50%, respectively. For distinguishing between benign and malignant AUS nodules, the AUC values of conventional ultrasonography, ultrasound elastography, superb microvascular imaging, and multimodal ultrasonography were 0.866, 0.745, 0.774, and 0.918, respectively. Conclusion Multimodal ultrasonography shows better diagnostic efficacy for AUS nodules of TI-RADS 3-5 compared with conventional ultrasonography, ultrasound elastography, and superb microvascular imaging, which can facilitate the malignancy risk stratification and management of AUS thyroid nodules.
		                        		
		                        		
		                        		
		                        	
10.Health risk assessment of inhalation exposure to metallic elements in PM2.5 in four cities of the Pearl River Delta in 2022
Jiwei NIU ; Suli HUANG ; Xiaoheng LI ; Zhen ZHANG ; Jiajia JI ; Ning LIU
Shanghai Journal of Preventive Medicine 2024;36(4):393-398
		                        		
		                        			
		                        			ObjectiveTo understand the characteristics of PM2.5 pollution in the air of Pearl River Delta city in Guangdong Province under the COVID-19 epidemic and the health risks of inhaling elements in PM2.5. MethodsIn 2022, 10 PM2.5 monitoring points were set up in 10 districts in Guangzhou, Shenzhen, Foshan and Zhuhai, and air samples were collected for 7 consecutive days every month to analyze the concentration of PM2.5 and the 12 elements in PM2.5. The classic "four-step" method was used to evaluate the carcinogenic risk and chronic non-carcinogenic risk of the elements in air PM2.5 on health. The age-sensitive characteristics of metal elements were combined in the carcinogenic risk assessment, and age-sensitive factors were introduced to analyze the impact of air pollution on population health. ResultsA total of818 samples were collected. and the average annual PM2.5 concentration in the four cities of the Pearl River Delta was 30.17 (1.00-166.00, s=21.06) μg·m-3, which was lower than the concentration limit of the secondary standard of the Ambient Air Quality Standard (GB 3095-2012). The difference of PM2.5 concentration in the four cities was statistically significant. The PM2.5 concentrations in Zhuhai and Shenzhen, which were located near the sea, were lower than those in Guangzhou and Foshan. The monthly mean concentration of PM2.5 in the four cities was the lowest at 13.70 (4.00-34.00, s=5.93) μg·m-3 in July and the highest at 57.73 (14.00-146.00, s=27.96) μg·m-3 in January, showing a low concentration from May to October and a high concentration from November to April of the following year. The average daily PM2.5 concentration exceeded the secondary standard for 29 days, mainly distributed in January and November. The average annual mass concentration of elements in PM2.5 in the four cities was Al>Mn>Pb>As>Ni>Cr>Se>Sb>Cd>Tl>Be>Hg. AS and Mn have chronic non-carcinogenic risk in population, while Cr, AS, Cd, Be and Ni have carcinogenic risk in population. ConclusionThe PM2.5 pollution levels of the four cities in the Pearl River Delta are low and variable. Coastal cities are lower than non-coastal cities, which shows the characteristics of first decreasing and then increasing throughout the year. The order of mass concentration of metal elements of PM2.5 in four cities is basically the same except Be and Ni. As and Mn in PM2.5 show a certain degree of chronic non-carcinogenic risk, and As, Cr, Cd, Ni and Be have a certain degree of carcinogenic risk. The four cities need to take effective intervention measures to continue to strengthen the pollution control and health protection of Cr, As, Cd and Mn in the air, and control the health burden caused by air pollution. 
		                        		
		                        		
		                        		
		                        	
            

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