Assessing the impact of drinking water iodine concentrations on the iodine intake of Chinese pregnant women living in areas with restricted iodized salt supply

PURPOSE

The supply of non-iodized salt and the water improvement project have been conducted to reduce the iodine concentration in drinking water in areas with elevated water iodine. We aimed to assess the impact of water iodine concentration (WIC) on the iodine intake of pregnant women in areas with restricted iodized salt supply, and determine the cutoff values of WIC in areas with non-iodized salt supply.

METHODS

Overall, 534 pregnant women who attended routine antenatal outpatient visits in Zibo Maternal and Child Health Hospital in Gaoqing County were recruited. The 24-h urine iodine excretion (UIE) in 534 samples and the iodine concentration in 534 drinking water samples were estimated. Urinary iodine excretion, daily iodine intake, and daily iodine intake from drinking water (WII) were calculated. The relationship between WIC and daily iodine take was analyzed.

RESULTS

The median WIC, spot urine iodine concentration (UIC), and 24-h UIE were 17 (6, 226) μg/L, 145 (88, 267) μg/L, and 190 (110, 390) μg/day, respectively. A significant positive correlation was found between WIC and UIE (R² = 0.265, p < 0.001) and UIC (R² = 0.261, p < 0.001). The contribution rate of WII to total iodine intake increased from 3.0% in the group with WIC of < 10 μg/L to 45.7% in the group with WIC of 50-99 μg/L.

CONCLUSION

The iodine content in drinking water is the major iodine source in pregnant women living in high-water iodine areas where iodized salt supply is restricted. The contribution rate of daily iodine intake from drinking water increases with the increase in water iodine concentration.

[Analysis on drug resistance-associated mutations of multi-drug resistant Mycobacterium tuberculosis based on whole-genome sequencing in China]

Objective: To analyze the resistance mutational profiles of multi-drug resistant Mycobacterium tuberculosis in China and the correlation between major mutation types and genotypes based on the whole-genome sequencing data. Methods: Search and download of the genome-wide sequencing data of M. tuberculosis published in China by August 2019 on NCBI database were conducted. Mutation frequency of drug resistance-related gene loci based on whole-genome sequencing was used to predict the molecular susceptibility of strains, and the correlation between mutation types and genotypes was analyzed. Results: According to the results of molecular resistance and susceptibility profiles, 1 024 MDR strains were identified from 2 019 M. tuberculosis strains. The major mutation types of resistance-related genes to common drugs were katG S315T (73.2%, isoniazid), rpoB S450L (63.1%, rifampicin), rpsL K43R (70.0%, streptomycin), embB M306V (37.4%, ethambutol), pncA_promoter T (-11)C (7.9%, pyrazinamide), gyrA A90V (32.3%, fluoroquinolones), rrs A1401G (67.7%, second-line injection drugs), fabG1_promoter C (-15) T (87.0%, Ethionamide), folC I43T (30.4%, P-aminosalicylic acid). Among them, the frequencies of katG S315T, embB M306V, rpsL K43R, gyrA A90V in lineage 2 were significantly higher than those in lineage 4, and folC I43T was only found in lineage 2. The proportion of katG S315T was significantly higher in the ancient Beijing genotype compared to the modern genotype, in contrast, the proportion of rpsL K43R was significantly higher in modern Beijing genotype, the differences were significant (all P<0.05). Conclusions: The results showed the main mutation types of resistance-related genes of MDR strains to many commonly used anti-tuberculosis drugs in China based on whole-genome sequencing, providing a basis for the development of sensitive and specific rapid molecular detection methods. At the same time, it was also found that the major mutation types of MDR-related genes were related to the genotype of the strains.

[Effectiveness evaluation of health belief model-based health education intervention for patients with hypertension in community settings]

Objective: To evaluate the effectiveness of health belief model-based health education intervention in improving blood pressure control of patients with hypertension in community settings. Methods: From September 2016 to September 2017, 400 newly diagnosed patients with hypertension were recruited from 6 community healthcare centers with comparable population size and health services in the Shunyi District of Beijing. All community healthcare centers were randomly assigned to the intervention group (206 patients) and the control group (194 patients). Patients in the intervention group received 3 lectures (20-30 min for each) of health belief model-based health education. Patients in the control group received usual care. The basic characteristics, health beliefs, and health literacy were collected, and blood pressure was measured before and after the intervention, respectively. The difference-in-difference model was used to analyze the change of blood pressure and the influencing factors between two groups before and after the intervention. Results: A total of 134 patients in the intervention group and 129 patients in the control group completed the study. After adjusting for the age, gender, family income, medical insurance, chronic diseases and family history, the score of perceived barriers was increased by 1.65 (P=0.016), and perceived seriousness was decreased by 0.73 (P=0.018). The systolic blood pressure of patients was decreased by 7.37 mmHg (1 mmHg=0.133 kPa, P=0.001) and diastolic blood pressure was decreased by 4.07 mmHg (P=0.014), respectively. The β (95%CI) values were -7.37 (-11.88,-2.86) and -4.07 (-7.30, -0.84). The perceived susceptibility and self-efficacy had a significant influence on the blood pressure of patients (P<0.05). Conclusion: Health belief model-based health education intervention could significantly improve the blood pressure control of patients with hypertension in the community settings.

[The cut-off points of body mass index and waist circumference for predicting metabolic risk factors in Chinese adults]

Objective: To assess the association of BMI and waist circumference (WC) with metabolic risk factors, and confirm the appropriate cut-off points of BMI and WC among Chinese adults. Methods: After excluding participants with missing or extreme measurement values, as well as individuals with self-reported histories of cancer, a total of 501 201 adults in baseline and 19 201 adults in the second re-survey from the China Kadoorie Biobank were included. The associations of BMI and WC with metabolic risk factors were estimated. Receiver operating characteristic (ROC) analyses were conducted to assess the appropriate cut-off values of BMI and WC to predict the risk of hypertension, diabetes, dyslipidemia and clustering of risk factors. Results: The prevalence of hypertension, diabetes, dyslipidemia and clustering of risk factors all presented ascending trends with the increasing levels of BMI or WC. Defined as the points on the ROC curve where Youden's index reached the highest, the appropriate overweight cut-off points of BMI were around 24.0 kg/m(2) both in men and women, and the points of WC were around 85 cm in men and 80 to 85 cm in women. With specificity 90% for identification of risk factors, the appropriate obese cut-off points of BMI were around 28.0 kg/m(2) both in men and women, with the range of 27.0 to 28.9 kg/m(2). Conclusions: The cut-off points for overweight and obesity recommended by Coorperative Meta-analysis Group of China Obesity Task Force was verified in the large sample survey conducted more recently. The cut-off points of BMI were 24.0 and 28.0 kg/m(2) for overweight and obesity, and the cut-off point of WC was 85 cm in men and 80 to 85 cm in women for central obesity.

[Association of body mass index and waist circumference with major chronic diseases in Chinese adults]

Objective: To examine the association of BMI with major chronic diseases morbidity and all-cause mortality in Chinese adults. Methods: This study is based on China Kadoorie Biobank. Anthropometric indexes were objectively measured at the baseline survey during 2004-2008. After excluding participants with heart disease, stroke, cancer, COPD and diabetes, 428 113 participants aged 30 to 79 years were included in the analysis. Cox regression models were used to investigate the associations of BMI and waist circumference with incidence of major chronic diseases (including cardiovascular disease, cancer, COPD, and type 2 diabetes) and all-cause mortality. Results: Over an average of 10 years, 131 454 participants developed any one of major chronic diseases. A total of 26 892 all-cause deaths were reported. The risk of major chronic diseases increased with BMI. Compared with normal BMI (18.5-24.0 kg/m(2)), the HR (95%CI) of overweight (BMI 24.0-28.0 kg/m(2)) and obesity (BMI≥28.0 kg/m(2)) were 1.26 (95%CI: 1.24-1.27) and 1.59 (95%CI: 1.57-1.62) respectively. Underweight and obesity were both associated with risk of all-cause mortality. Waist circumference was positively associated with risk of major chronic diseases and all-cause mortality. According to recommended cut-off points of BMI and waist circumference for Chinese adults, maintaining a healthy body weight would prevent 12% incident cases of major chronic diseases. Conclusion: General and central obesity were risk factors for major chronic disease among Chinese adults.

Does the Brown classification of maxillectomy defects have prognostic prediction for patients with oral cavity squamous cell carcinoma involving the maxilla?

The aim of this study was to investigate the correlation between the maxillectomy defect, T stage, and prognosis of patients with maxillary squamous cell carcinoma (SCC). The Brown classification system was used to appraise the maxillectomy defects due to maxillary SCC. The clinical data of 137 patients with maxillary SCC during the period 2000-2010 were reviewed; 105 patients were followed up. Preoperative T stage and postoperative maxillectomy class were recorded. The relationship between the maxillectomy defect class and T stage of maxillary SCC was analysed. Correlations between the maxillectomy defect class, local recurrence rate, and survival rate were assessed using IBM SPSS Statistics v19.0. The most common maxillectomy defect class was IIb (54.7%, 75/137). The maxillectomy defect class was significantly associated with the T stage (P < 0.001). Both T stage and the maxillectomy defect class were significantly associated with the survival rate of patients with maxillary SCC (both P< 0.001). In conclusion, the class of the maxillectomy defect was found to be associated with the T stage. Both of these were prognostic factors for patients with maxillary SCC. The class of the maxillectomy defect is suitable for clinical application in predicting the prognosis compared with T stage.

Prevalence and antimicrobial resistance of Salmonellaisolates from goose farms in Northeast China

BACKGROUND

Salmonella is one of the most important enteric pathogenic bacteria that threatened poultry health.

AIMS

This study aimed to investigate the prevalence and antimicrobial resistance of Salmonella isolates in goose farms.

METHODS

A total of 244 cloacal swabs were collected from goose farms to detect Salmonella in Northeast China. Antimicrobial susceptibility, and resistance gene distribution of Salmonella isolates were investigated.

RESULTS

Twenty-one Salmonella isolates were identified. Overall prevalence of Salmonella in the present study was 8.6%. Among the Salmonella isolates, the highest resistance frequencies belonged to amoxicillin (AMX) (85.7%), tetracycline (TET) and trimethoprim/sulfamethoxazole (SXT) (81%), followed by chloramphenicol (CHL) (76.2%), florfenicol (FLO) (71.4%), kanamycin (KAN) (47.6%), and gentamycin (GEN) (38.1%). Meanwhile, only 4.8% of the isolates were resistant to ciprofloxacin (CIP) and cefotaxime (CTX). None of the isolates was resistant to cefoperazone (CFP) and colistin B (CLB). Twenty isolates (95%) were simultaneously resistant to at least two antimicrobials. Ten resistance genes were detected among which the bla _TEM-1, cmlA, aac(6')-Ib-cr, sul1, sul2, sul3, and mcr-1.1 were the most prevalent, and presented in all 21 isolates followed by tetB (20/21), qnrB (19/21), and floR (15/21).

CONCLUSION

Results indicated that Salmonella isolates from goose farms in Northeast China exhibited multi-drug resistance (MDR), harboring multiple antimicrobial resistance genes. Our results will be useful to design prevention and therapeutic strategies against Salmonella infection in goose farms.

Dynamic characteristics of AHLs-secreting strain Aeromonas sp. A-L2 and its bioaugmentation during quinoline biodegradation

AIMS

In order to probe a more environmentally friendly method of pollutant treatment based on microbial bioaugmentation and quorum sensing (QS) effects.

METHODS AND RESULTS

The dynamic characteristics and QS effects of the acylated homoserine lactones (AHLs)-secreting strain Aeromonas sp. A-L2 (A-L2), which was isolated from the activated sludge system, was discussed. According to the liquid chromatography-mass spectrometry results, N-butyryl-homoserine lactone (C4-HSL) and N-hexanoyl-homoserine lactone (C6-HSL) were the major AHLs secreted by strain A-L2, and the swarming of strain Ochrobactrum sp. LC-1 (LC-1) was induced by these compounds. The extracellular polymeric substance secretion of the strain LC-1 was mainly led by C6-HSL, and the biofilm formation ability was mainly influenced by C6-HSL or C4-HSL (60 μg l^-1 ). The optimal AHLs secretion conditions of strain A-L2 were also studied. Drawing support from the AHLs-secreting strain A-L2 during quinoline degradation by strain LC-1, the degradation time was greatly shortened.

CONCLUSIONS

Hence, AHLs-secreting strain A-L2 can be useful as an AHLs continuous supplier during bioaugmentation and pollutant biodegradation.

SIGNIFICANCE AND IMPACT OF THE STUDY

The bioaugmentation process of strain A-L2 on quinoline biodegradation based on QS effects would lay a certain theoretical and practical significance for large-scale applications.

Measurement of the cosmic ray proton spectrum from 40 GeV to 100 TeV with the DAMPE satellite

The precise measurement of the spectrum of protons, the most abundant component of the cosmic radiation, is necessary to understand the source and acceleration of cosmic rays in the Milky Way. This work reports the measurement of the cosmic ray proton fluxes with kinetic energies from 40 GeV to 100 TeV, with 2 ¹/₂ years of data recorded by the DArk Matter Particle Explorer (DAMPE). This is the first time that an experiment directly measures the cosmic ray protons up to ~100 TeV with high statistics. The measured spectrum confirms the spectral hardening at ~300 GeV found by previous experiments and reveals a softening at ~13.6 TeV, with the spectral index changing from ~2.60 to ~2.85. Our result suggests the existence of a new spectral feature of cosmic rays at energies lower than the so-called knee and sheds new light on the origin of Galactic cosmic rays.

Recognizing basal cell carcinoma on smartphone-captured digital histopathology images with a deep neural network

BACKGROUND

Pioneering effort has been made to facilitate the recognition of pathology in malignancies based on whole-slide images (WSIs) through deep learning approaches. It remains unclear whether we can accurately detect and locate basal cell carcinoma (BCC) using smartphone-captured images.

OBJECTIVES

To develop deep neural network frameworks for accurate BCC recognition and segmentation based on smartphone-captured microscopic ocular images (MOIs).

METHODS

We collected a total of 8046 MOIs, 6610 of which had binary classification labels and the other 1436 had pixelwise annotations. Meanwhile, 128 WSIs were collected for comparison. Two deep learning frameworks were created. The 'cascade' framework had a classification model for identifying hard cases (images with low prediction confidence) and a segmentation model for further in-depth analysis of the hard cases. The 'segmentation' framework directly segmented and classified all images. Sensitivity, specificity and area under the curve (AUC) were used to evaluate the overall performance of BCC recognition.

RESULTS

The MOI- and WSI-based models achieved comparable AUCs around 0·95. The 'cascade' framework achieved 0·93 sensitivity and 0·91 specificity. The 'segmentation' framework was more accurate but required more computational resources, achieving 0·97 sensitivity, 0·94 specificity and 0·987 AUC. The runtime of the 'segmentation' framework was 15·3 ± 3·9 s per image, whereas the 'cascade' framework took 4·1 ± 1·4 s. Additionally, the 'segmentation' framework achieved 0·863 mean intersection over union.

CONCLUSIONS

Based on the accessible MOIs via smartphone photography, we developed two deep learning frameworks for recognizing BCC pathology with high sensitivity and specificity. This work opens a new avenue for automatic BCC diagnosis in different clinical scenarios. What's already known about this topic? The diagnosis of basal cell carcinoma (BCC) is labour intensive due to the large number of images to be examined, especially when consecutive slide reading is needed in Mohs surgery. Deep learning approaches have demonstrated promising results on pathological image-related diagnostic tasks. Previous studies have focused on whole-slide images (WSIs) and leveraged classification on image patches for detecting and localizing breast cancer metastases. What does this study add? Instead of WSIs, microscopic ocular images (MOIs) photographed from microscope eyepieces using smartphone cameras were used to develop neural network models for recognizing BCC automatically. The MOI- and WSI-based models achieved comparable areas under the curve around 0·95. Two deep learning frameworks for recognizing BCC pathology were developed with high sensitivity and specificity. Recognizing BCC through a smartphone could be considered a future clinical choice.

[Diagnostic value of endoscopic ultrasonography, fibroscan, acoustic radiation pulse imaging, serological index, and their combination for early stage liver cirrhosis]

Objective: To investigate the diagnostic value of endoscopic ultrasonography (EUS), Fibroscan, acoustic radiation force impulse (ARFI), and aspartate aminotransferase-to-platelet ratio (APRI) and their combination for early stage liver cirrhosis. Methods: Three hundred and twenty-two hospitalized patients who had been diagnosed with chronic viral liver disease from March 2016 to April 2018 were included. According to the clinical diagnosis, patients were divided into chronic hepatitis and the early stage liver cirrhosis group (Child-Pugh A grade). All patients were examined by Fibroscan to detect liver stiffness measurement (LSM), ARFI to detect liver virtual touch tissue quantification (VTQ) value, esophagogastroduodenoscopy and EUS to detect esophagogastric varices, laboratory and imaging examination. The index of EUS, Fibroscan, ARFI, and APRI was analyzed and the regression model was established by binary logistic regression, and the diagnostic efficacy of the above index and regression model for early stage of cirrhosis was evaluated by the area under a receiver operating characteristic curve (AUROCs). Results: An early stage cirrhosis group had significantly higher detection rate with EUS (esophagogastric varices), Fibroscan (LSM), ARFI (VTQ) and APRI than chronic hepatitis group [76.7% vs. 10.7%, 10.4 (7.8, 17.3) vs. 6.1 (5.2, 8.4) kPa, 1.71(1.48, 2.07) m/s vs. 1.25(1.14, 1.43) m/s and 0.65 (0.38, 1.15) vs. 0.38(0.26, 0.62), respectively]. The corresponding chi-square test were 140.86, Z = -9.069, Z = -9.948 and Z = -5.764, respectively and the differences were statistically significant (P < 0.01). The areas under the receiver operating characteristic curve and regression model were 0.830 (0.783 ~ 0.877), 0.793 (0.744 ~ 0.841), 0.821 (0.775 ~ 0.868), 0.686 (0.628 ~ 0.744) and 0.947 (0.925 ~ 0.969) for the diagnosis of early stage cirrhosis, respectively. Among them, the regression model of three indices (EUS, LSM and VTQ) had the largest AUROCs (0.947) and the corresponding sensitivity and specificity were 0.878 and 0.867, respectively. Conclusion: The combination of EUS, LSM and ARFI had a superior diagnostic value for early stage liver cirrhosis, and may improve the diagnosis rate and reduce the misdiagnosis rate.

[Analysis on influencing factors that leading to nonspecific responses to indeterminate results of HIV antibodies]

Objective: To identify the influencing factors that leading to nonspecific responses to indeterminate HIV antibody tests, to provide scientific evidence for the differential diagnosis of HIV infection and control strategy. Methods: A case control study was conducted. The samples of HIV antibody indeterminate in confirmed Western blot (WB) tests, but were negative in HIV nucleic acid tests, were collected as HIV antibody indeterminate group from WB results of HIV confirmatory laboratories of Fujian province in 2015-2016. The general population matched group with HIV antibody screening negative samples and WB negative matched group with WB negative samples were selected as the two compared groups by matching gender and age from HIV antibody screening in Fujian province in the same period. Blood concentrations of hepatitis B surface antigen (HBsAg), anti-hepatitis C virus (HCV) antibody, anti-treponema pallidum (TP) antibody, antinuclear antibody (ANA), anti-human T-cell leukemia virus (HTLV) antibody, and alpha-fetoprotein (AFP) were detected by using enzyme-linked immunosorbent assay (ELISA). χ(2) test and multivariate non-conditional logistic regression analysis were performed to identify the influencing factors that leading to nonspecific responses, to indeterminate HIV antibody tests. Results: A total of 13 WB band patterns were observed in 110 HIV antibody indeterminate samples, in which a single p24 band (58.18%, 64/110), a single gp160 band (17.27%, 19/110) and a single p17 band (7.27%, 8/110) were the three most common patterns. The positive rate of anti-TP antibody was significantly higher in HIV antibody indeterminate samples than general population control group and WB negative control group (10.91%, 12/110 vs. 1.77%, 4/226 and 3.64%, 4/110), compared with two control groups (χ(2)=13.627 and 4.314, P<0.05). The positive rate of AFP was significantly higher in HIV antibody indeterminate samples than general population control group (18.18%, 20/110 vs. 0.44%, 1/226, χ(2)=39.736, P<0.05), the different was not significant compared with WB negative control group (18.18%, 20/110 vs. 23.64%, 26/110, χ(2)=0.990, P>0.05) While no significant differences were found between HIV antibody indeterminate group and two control groups in terms of the positive rates of ANA, HBsAg, anti-HCV antibody or anti-HTLV antibody. Conclusions: The influencing factors that leading to nonspecific responses to indeterminate HIV antibody tests appeared complicate, and the anti-TP antibody positivity might be an influencing factor responsible for nonspecific responses to indeterminate HIV antibody tests.

[Role of signaling pathway of long non-coding RNA growth arrest-specific transcript 5/microRNA-200c-3p/angiotensin converting enzyme 2 in the apoptosis of human lung epithelial cell A549 in acute respiratory distress syndrome]

Objective: To investigate whether long non-coding RNA (lncRNA) growth arrest-specific transcript 5 (GAS5)/microRNA-200c-3p/angiotensin converting enzyme 2(ACE2) involved in the regulation of the apoptosis of human lung epithelial cell A549 in acute respiratory distress syndrome (ARDS). Methods: ARDS rat models were established and were divided into control, ARDS, ARDS+ pcDNA and ARDS+ pcDNA-GAS5 groups. Six hours after the establishment of ARDS rat model, arterial blood and lung tissues of the rats from the four groups were collected. The changes of partial pressure of oxygen (PO(2)) and partial pressure of CO(2) (PCO(2)) were analyzed and the expression of GAS5 in lung tissue was observed in these groups. Then, A549 cells were divided into control, lipopolysaccharide (LPS), LPS+ pcDNA, LPS+ pcDNA-GAS5, LPS+ pcDNA-GAS5+ pre-NC, LPS+ pcDNA-GAS5+ miR-200c-3p mimic groups. Quantitative real-time PCR (qRT-PCR) was conducted to measure lncRNA GAS5, ACE2 and miR-200c-3p levels. RNA immunoprecipitation and RNA pull-down assay were used to detect the combination between GAS5 and miR-200c-3p. Western blotting was used to detect the protein level of ACE2. Flow cytometry was used to observe the apoptosis of A549 cells in those groups. The data between groups were compared by t test. Results: In ARDS rat model, PO(2) value was significantly increased in ARDS+ pcDNA-GAS5 group than that in ARDS+ pcDNA group[(81.5±3.3) vs (57.5±5.1) mmHg, t=4.850, P<0.05], and PCO(2) value was significantly decreased in ARDS+ pcDNA-GAS5 group than that in ARDS+ pcDNA group[(50.6±1.9) vs (64.0±1.9) mmHg, t=5.940, P<0.05]. LncRNA GAS5 level in A549 cells of LPS group decreased significantly than that in control group (0.43±0.01 vs 1.01±0.01, t=0.242, P<0.05). Compared with LPS+ pcDNA group, ACE2 expression increased significantly in LPS+ pcDNA-GAS5 group (0.85±0.04 vs 0.34±0.02, t=1.800, P<0.05). Compared with LPS+ pcDNA-GAS5+ pre-NC group, ACE2 expression decreased significantly in LPS+ pcDNA-GAS5+ miR-200c-3p mimic group (0.62±0.01 vs 0.84±0.02, t=9.440, P<0.05). Compared with control group, the percentage of A549 cell apoptosis promoted significantly in LPS group (25.90±0.61 vs 7.90±0.22, t=0.257, P<0.05). Compared with LPS+ pcDNA group, the percentage of A549 cell apoptosis suppressed significantly in LPS+ pcDNA-GAS5 group (10.50±0.37 vs 26.37±0.45, t=1.760, P<0.05). Compared with LPS+ pcDNA-GAS5+ pre-NC group, the percentage of A549 apoptosis promoted significantly in LPS+ pcDNA-GAS5+ miR-200c-3p mimic group (19.07±0.56 vs 10.87±0.26, t=0.643, P<0.05). Conclusion: In ARDS, down-regulation of lncRNA GAS5 decreases ACE2 expression through increasing miR-200c-3p to promote the apoptosis of A549 cells, thus to promote the progression of ARDS.

[Analysis of characteristics and influencing factors of fine particulate matters and submicron particulate matters in printing shop]

Objective: To analyze the physical characteristics of fine particulate matters (PM(2.5)) and submicron particulate matters (PM(1)), and investigate the factors influencing the emission peak of printer particles. Methods: A 12-hour particle concentration monitoring for PM(2.5) and PM(1) was conducted in a printing shop on January 5(th), 2018. PM(2.5) in the air was analyzed after the monitoring process to figure out morphological characteristics and element composition of printer particles. Besides, experiments were carried out in an enclosed space to detect the number concentration peaks of PM(1) during every printing process. Influencing factors investigated in this study were printer types, toner coverages and interval time between different printing processes. Results: The 12-hour particles concentration monitoring showed that the number concentration of PM(1) and the mass concentration of PM(2.5) were 7.510×10(4) pt/cm(3) and 96.85 μg/m(3). The diameter of most PM(2.5) was less than 100 nm, with a fractal dimension of 2.591. Most PM(2.5) appeared as regular spheres with typical agglomeration phenomenon, while some were in rhabditiform or irregular shapes. Element analysis showed that PM(2.5) was mainly composed of C, O, Si, Ca, with less metallic element. The PM(1) emission peak values of three printers were 3.60×10(4), 3.43×10(4), 0.31×10(4) pt/cm(3), respectively and the difference was not statistically significant (χ(2)=5.42, P>0.05). When the page coverage rate was 0%, 2.5%, 5%, 10%, 20% and 50%, the PM(1) emission peak value of printer A was 6.74×10(4), 4.62×10(4), 3.82×10(4), 2.82×10(4), 1.00×10(4) and 1.08×10(4) pt/cm(3), and the difference was also not statistically significant (χ(2)=7.01, P>0.05). The natural logarithm of PM(1) emission peak value in printing work was associated with the resting time before printing and the change value of heating roller temperature (r value was 0.83 and 0.89, respectively, all P values<0.05). Conclusion: PM(2.5) and PM(1) in the printing shop stayed at a high level. Particles appeared as various shapes and element compositions were complex. The temperature change of heating roller was one of most important factors that lead to the increased number concentration peak of PM(1).