Relationship between Ambient Fine Particles and Ventricular Repolarization Changes and Heart Rate Variability of Elderly People with Heart Disease in Beijing, China

Objective To explore the effects of particulate matters less than 2.5 μm in aerodynamic diameter （PM2.5） on heart repolarization/depolarization and heart rate variability （HRV）. Methods We conducted a panel study for elderly subjects with heart disease in Beijing from 2007 to 2008. PM2.5 was measured at a fixed station for 20 h continuously each day while electrocardiogram （ECG） indexes of 42 subjects were also recorded repeatedly. Meteorological data was obtained from the China Meteorological Data Sharing Service System. A mixed linear regression model was used to estimate the associations between PMz.s and the ECG indexes. The model was adjusted for age, body mass index, sex, day of the week and meteorology. Results Significant adverse effects of PM2.5 on ECG indexes reflecting HRV were observed statistically and the strongest effect of PM2.s on HRV was on lag i day in our study. However, there were no associations between PM2.5 and ECG indexes reflecting heart repolarization/depolarization. Additionally, the effects of PM2.5 on subjects with hypertension were larger than on the subjects without hypertension. Conclusion This study showed ambient PM2.5could affect cardiac autonomic function of the elderly people with heart disease, and subjects with hypertension appeared to be more susceptive to the autonomic dysfunction induced by PM2.5.

Molecular and Epidemiological Characterization of Infant Botulism in Beijing, China

Laboratory-based pathogen isolation, identification, and toxicity determination were performed on samples from a suspected case of infant botulism. Mice injected with cultures generated from the enema sample and ingested Powered infant formula （PIF） presented typical signs of botulism. Antitoxins to polyvalent botulinum neurotoxins （BoNTs） and monovalent BoNT type B antitoxin had protective effects. Clostridium botulinum isolated from the enema and residual PIF samples were positive for type B toxin. Pulsed-field gel electrophoresis （PFGE） revealed that the two strains of C. botulinum isolated from the two samples produced indistinguishable pulsotypes. These findings confirmed this case of type B infant botulism associated with the ingestion of PIF contaminated bv type B C. botulinum spores.

Social Determinants of Health Behaviors in Primary School Children：A Cross-sectional Study of both Migrant and Resident Children in Beijing,China

Childhood risky behaviors always result in adverse health outcomes. These behaviors are greatly affected by social environment and individual factors. However, few studies explored the social determinants of schoolchildren＇s health behaviors. In this cross-sectional study, the social determinants of health behaviors were examined among both migrant and resident students in Beijing, China. Data of 967 children from six urban and suburban primary schools were analyzed using multiple linear regression analysis. The results showed that less than 60% of children performed some healthy behaviors, although their health knowledge was generally good. Children＇s health behavior scores were greatly determined by school characteristics, health knowledge, demographic characteristics, and family context. Therefore, improving health education and conditions in primary schools is the priority to promote children＇s healthy behaviors, especially for disadvantaged children.

Field Evaluation of Alternative Testing Strategies for the Detection of HIV Infection in Beijing

To identify a cost-efficient altemative antibody testing strategy for screening and confirmation of HIV infection by rapid simple tests （RSTs） and enzyme-linked immunosorbent assays （ELISAs）. Methods Four RSTs （RST1, RST2, RST3, and RST4 ） and five ELISAs （ELISA1, ELISA2, ELISA3, ELISA4, and ELISA5） were evaluated in two phases by using banked and serum specimens prospectively collected at regional hospitals and voluntary counseling and testing （VCT） centers in Beijing. A total of 200 banked serum specimens were included in the first phase, including 62 HIV-positive, 127 HIV-negative and 11 indeterminate specimens. All specimens were tested by four RSTs and five ELISAs respectively. The second phase involved prospective testing of 389 routine specimens, including 92 HIV-positive, 287 HIV-negative, and 10 indeterminate specimens. All the specimens were tested by two RSTs （RST2 and RST4） and three ELISAs （ELISA1, ELISA3, and ELISA4）, which were selected for their respective excellent sensitivity and/or specificity. Westem blot （WB） was used as a gold standard for confirming the reactivity of all the specimens. Results Sensitivity, specificity, and efficacy were calculated for each assay in two phases. In the first phase, four assays （ELISA4, RST2, RST3, and RST4） had a specificity of 100%. For the determination of efficacy, ELISA4, RST2, and RST4 were selected in the second phase. ELISA1 and ELISA3 which have a sensitivity of 95.9% and 93.2% respectively also entered this phase. In the second phase, all the five assays （ELISA1, ELISA3, ELISA4, RST2, and RST4） had a sensitivity and specifity of over 90%. ELISA1 had a sensitivity of 99% and ELISA4 a specificity of 99%. Conclusion The sensitivity ELISA1 and the specificit of ELISA4 are comparable to ELISA/WB standard strategy. Application of this alternative testing strategy provides a cost-effective method for determining HIV prevalence in Beijing.

Risk Factors for SARS-Related Deaths in 2003, Beijing

Objective To study the potential risk factors for severe acute respiratory syndromes （SARS）-related deaths in Beijing. Methods Epidemiological data were collected among the confirmed SARS patients officially reported by Beijing Centers for Disease Control and Prevention （BCDC）, and information was also supplemented by a follow-up case survey, Chi-square test and multivariate stepwise logistic regression analysis were performed. Results Old age （over 60 years） was found to be significantly associated with SARS-related deaths in the univariate analysis. Also, history of contacting SARS patients within 2 weeks prior to the onset of illness, health occupation, and inferior hospital ranking as well as longer interval of clinic consulting （longer than 1 day） were the risk factors for SARS-related deaths. Multivariate stepwise logistic regression analysis found four risk factors for SARS-related deaths. Conclusion Old age （over 60 years） is the major risk factor for SARS-related deaths. Moreover, hospital health workers, the designated hospitals for SARS clinical services and the interval of consulting doctors （less than 1 day） are protective factors for surviving from SARS.

Studies on the Levels of Indoor PM10 and PM2.5 in Public Places in Chaoyang District, Beijing

[Objective]The research aimed to understand the levels of indoor air particles of PM_(10) and PM_(2.5)in public places in Chaoyang District of Beijing City,which will provide scientific basis for making health standards and policies and regulations of indoor air particulate matter in public places.[Method]In order to characterize indoor air quality of public places,shopping mall near the walking street,shopping mall near arterial traffic,barbecue style restaurant and eat hutch unicom Chinese restaurant were selected for this study.LD-3Claser measuring dust detector and Sidepak AM-510 artificial intelligence anti-explosion dust detector were used to test the levels of PM_(10) and PM_(2.5)in the air of the shopping malls and restaurants.The number of smoking customers and if smelling the smoke were recorded simultaneously.[Result]The average densities of PM_(10) and PM_(2.5)in the shopping mall near the walking street were noticeably lower than that near arterial traffic(P< 0.05).The highest level of PM_(2.5)at the barbecue style restaurant and eating hutch unicom Chinese restaurants were 1 090and666g/m^3.The average levels of PM_(10) at the barbecue style restaurant and eating hutch unicom restaurants were 286 and 399g/m3(P<0.05).[Conclusion]The indoor PM_(10) and PM_(2.5)concentrations were high in public places,especially in shopping mall near arterial traffic and restaurant.It should be enhanced to supervise indoor air in public places and establish the risk rating of indoor air quality to protect public health.

Screening for Plant Toxins in Honey and Herbal Beverage by Ultrahigh-Performance Liquid Chromatography-Ion Mobility-Quadrupole Time of Flight Mass Spectrometry

The standards of plant toxins were separated by a C18 column with gradient elution with 0.1% formic acid/water (V/V) and 0.1% formic acid/acetonitrile (V/V) as mobile phase and acquired by ion mobility-quadrupole time of flight mass spectrometry (IM-QTOF MS) in positive ion mode. A database of 308 plant toxins including retention time, collision cross-section (CCS) and its fragment ions was established. Honey dissolved in water or herbal beverage was extracted by acetonitrile and purified with PSA sorbent, and then acquired by ultrahigh-performance liquid chromatography IM-QTOFMS. The acquired data were processed by comparing with the database we established to confirm the target compounds. The average recoveries for samples at two levels ranged from 60.6% - 120.1%, with relative standard deviation (n = 6) less than 25%. The limit of quantitation for plant toxins ranged from 1 - 20 μg/kg. The developed screening method was used in determination of honey, herbal beverage and honey flavored tea beverage samples. The results showed that berberine was detected in one honey with 1 μg/kg and caffeine was present in some beverages with the concentration from 200 and 5500 μg/kg. This method could meet the requirement for rapid screening of plant toxins in honey and herbal beverage. It can be used for the quality control of honey and herbal beverage in enterprises or quality inspection departments. It also can be used in the rapid screening of food poisoning.

Trends in Lipids Level and Dyslipidemia among Chinese Adults, 2002-2015

Objective To investigate the trends of lipid profiles and dyslipidemia among Chinese adults from 2002 to 2015.Methods Data were collected from three nationally representative cross-sectional surveys.Fasting venous blood samples were collected and serum lipids were tested by biochemical analysis and enzymatic determination.Lipid levels and the prevalence of dyslipidemia among adults were analyzed with complex sampling weighting adjustment for age and gender.Results The weighted means of TC, TG, and LDL-c significantly increased linearly from 3.93, 1.12, and 2.12 mmol/L in 2002 to 4.59, 1.41, and 2.78 mmol/L in 2010 and then to 4.63, 1.47, and 2.87 mmol/L in 2015, respectively;by contrast, HDL-c levels decreased significantly from 1.30 mmol/L to 1.26 mmol/L over the same period.Similar trends in mean non-HDL-c and lipid-related ratios were observed.The weighted dyslipidemia prevalence linearly increased;in particular, hypercholesterolemia increased from 1.6% to 5.6% and then to 5.8%, hypertriglyceridemia increased from 5.7% to 13.6% and then to 15.0%, low HDL-c increased from 18.8% to 35.5% and then to 24.9%, and high LDL-c increased from 1.3% to 5.6% and then to 7.2%(P for trend <0.001).Conclusion Dyslipidemia increased among Chinese adults from 2002 to 2015.Development of a comprehensive strategy to decrease lipid levels in this population is urgently required.

Blood Lipid Profile and Prevalence of Dyslipidemia in Chinese Adults

To investigate the plasma lipid levels in a national representative sample of subjects and to determine the prevalence of dyslipidemia in the Chinese population. Methods Plasma lipid profile was analyzed using the data obtained during the Chinese national nutrition and health survey （CNHS） in 2002 which involved 14 252 participants at the age of 18 years or older. Results The mean levels of total cholesterol （TC）, triglyceride （TG） and high density lipoprotein cholesterol （HDL-C） in the participants were 3.81 retool/L, 1.10 mmol/L, and 1.30 mmol/L, respectively. In the groups of participants at the age of 18-44 years, 45-59 years, and over 60 years the mean TC level was 3.70 mmol/L, 4.09 mmol/L and 4.21 mmol/L, respectively, and the mean TG level was 07 mmol/L, 1.21 mmol/L, 1.20 mmol/L, 1.29 mmol/L, 1.33 mmol/L, and 1.33 mmol/L, respectively. The prevalence of dyslipidemia in Chinese adults was 18.6% and 22.2% in males and 15.9% in females. Dyslipidemia prevalence was higher in urban districts than in rural areas （21.0% vs. 17.7%）. The prevalence of hypercholesterolemia, hypertriglyceridemia, and low HDL cholesterol was 2.9%, 11.9%, and 7.4% respectively among the participants. Conclusion Dyslipidemia has become one of the important health risk factors in the Chinese population. There is no significantly difference in the prevalence of dyslipidemia between the groups of participants at the age of 45-59 years and over 60 years. This study provides important lipid profile data for policy making and guideline development for the prevention of dyslipidemia in the Chinese population.

Determination of Taurine in Biological Samples by High-Performance Liquid Chromatography Using 4-Fluoro-7-Nitrobenzofurazan as a Derivatizing Agent

Objective A highly sensitive and rapid high‐performance liquid chromatography method with pre‐column derivatization with 4‐fluoro‐7‐nitrobenzofurazan was developed for determination of taurine in biological samples,including plasma,brain,and liver.Methods The optimum derivatization reaction temperature was 70℃,and at this temperature the reaction was complete within 3 min.The derivatized taurine was separated using phosphate buffer （0.02 mol/L,pH 6.0）：acetonitrile （84：16,v/v） as the mobile phase at a flow rate of 1.0 mL/min,and a column temperature of 25℃.The taurine derivatives were separated within 20 min （tR：14.5 min） and fluorometrically detected at 530 nm with excitation at 470 nm.Results The intra‐ and the inter‐day coefficients of variation for the method were 5.3% and 7.7%,respectively.The calibration curve was linear from 0.1 μmol/L to 30.0 μmol/L with a correlation coefficient of 0.9995.Conclusion This method can be used to determine the taurine contents in plasma,brain,and liver from normal rats and human plasma.

Risk Factors of Low Back Pain among the Chinese Occupational Population:A Case-control Study

Objective To explore the risk factors of low back pain among the Chinese occupational population in several major industries. Methods A total of 7200 subjects （3600 cases and 3600 controls） were randomly sampled from a cross-sectional study, and they were investigated for individual and occupational factors of low back pain. The potential risk factors were first selected by using chi-square tests. Secondly, collinearity diagnosis proceeded by using the Kendall＇s rank correlation. Finally, binary logistic regression model was used for multi-factor analysis. Results Collinearity diagnosis showed that there was a severe collinearity problem among the potential risk factors of low back pain. Logistic regression model included 20 variables with statistical significance. Bending neck forward or holding neck in a forward posturefor long periods （0R=1.408） was the most important risk factor inducing low back pain in this study, followed by bending heavily with the trunk （0R=1.402）, carrying out identical work almost for the whole day （0R=1.340）. Additionally, suHicient normal break was a protective factor of low back pain. Conclusion Low back pain among the Chinese occupational population was associated with body height, occupation, work organization, physical work, working posture, and others. All these risk factors could be regarded as the indicators of low back pain, and some relevant preventive measures should be taken to reduce low back pain risk.

Rapid and High-throughput Identification of Recombinant Bacteria with Mass Spectrometry Assay

Objective To construct a rapid and high-throughput assay for identifying recombinant bacteria based on mass spectrometry. Methods Matrix assisted laser desorption ionization time-of-flight mass spectrometry （MALDI-TOF MS） techniques were used to identify 12 recombinant proteins （10 of Yersinia pestis, 1 of Campylobacter jejuni and 1 of Helicobacter pylori）. A classification model for the various phase of recombinant bacteria was established, optimized and validated, using MALDI-TOF MS-CIinProTools system. The differences in the peptide mass spectra were analyzed by using Biotyper and FIexAnalysis softwares. Results Models of GA, SNN, and QC were established. After optimizing the parameters, the GA recognition model showed good classification capabilities： RC=100%, mean CVA=98.7% （the CVA was 96.4% in phase 1, 100% in phase 2, 98.4% in phase 3, and 100% in phase 4, respectively） and PPV=95}. This model can be used to classify the bacteria and their recombinant, which only requires 3.7x103 cells for analysis. The total time needed is only 10 min from protein extraction to reporting the result for one sample. Furthermore, this assay can automatically detect and test 96 samples concurrently. A total of 48 specific peaks （9, 16, 9, and 14 for the four stages, respectively） was found in the various phase of recombinant bacteria. Conclusion MALDI-TOF MS can be used as a fast, accurate, and high-throughput method to identify recombinant bacteria, which provide a new ideas not only for recombinant bacteria but also for the identification of mutant strains and bioterrorism pathogens.

Assessing Heat-related Mortality Risks in Beijing,China

Objective To obtain the exposure-response relationship for temperature and mortality, and assess the risk of heat-related premature death. Methods A statistical model was developed using a Poisson generalized linear regression model with Beijing mortality and temperature data from October 1st, 2006 to September 30th, 2008. We calculated the exposure-response relationship for temperature and mortality in the central city, and inner suburban and outer suburban regions. Based on this relationship, a health risk model was used to assess the risk of heat-related premature death in the summer （June to August） of 2009. Results The population in the outer suburbs had the highest temperature-related mortality risk. People in the central city had a mid-range risk, while people in the inner suburbs had the lowest risk. Risk assessment predicted that the number of heat-related premature deaths in the summer of 2009 was 1581. The city areas of Chaoyang and Haidian districts had the highest number of premature deaths. The number of premature deaths in the southern areas of Beijing （Fangshan, Fengtai, Daxing, and Tongzhou districts） was in the mid-range. Conclusion Ambient temperature significantly affects human mortality in Beijing. People in the city and outer suburban area have a higher temperature-related mortality risk than people in the inner suburban area. This may be explained by a temperature-related vulnerability. Key words： Temperature; Mortality; Premature death; Health risk; Generalized linear regression model; Climate change

Gender-specific Association of Sleep Duration with Body Mass Index,Waist Circumference,and Body Fat in Chinese Adults

Objective To examine the association between habitual sleep duration and obesity among Chinese adults. Methods The association of sleep duration and obesity was investigated among 7,094 community-dwelling Chinese adults. Sleep duration was self-reported. In this study, obesity was defined as follows： body mass index （BMI） ≥ 28 kg/m^2, waist circumference （WC） ≥ 85 cm in men and ≥ 80 cm in women, and percent body fat （%BF） ≥ 25 in men and ≥ 35 in women. Logistic and quantile regressions were employed to examine relationships of interest. Results Overall, 6.42% of the participants reported short sleep durations （〈 6 h/d） while 14.71% reported long （≥ 9 h/d） sleep durations. Long sleepers （≥ 9 h/d） represented a greater frequency of women with obesity [odds ratio （OR）： 1.30; 95% confidence interval （CI）, 1.02-1.67] and high body fat （1.43, 1.04-1.96） than those who slept 7-8 h/d. An association between long sleep times and higher BMI estimations was found across the 10th-75th percentile of the BMI distribution. Among men, long sleepers （≥ 9 h/d） presented lower risks of developing abdominal obesity compared with individuals who slept 7-8 h/d （OR = 0.79, 95% CI： 0.44-0.99）. Conclusion Our study suggests that long sleep durations are associated with general obesity in Chinese women but reduced waist circumferences in men. Confirmatory studies are needed to determine the heterogeneous association of sleep time and obesity by gender.

Identification of human cytomegalovirus phosphoprotein 65 in C57BL/6 and BXSB mice as a potential trigger of systemic lupus erythematosus related serum markers

Objective:To investigate the potential role of human cytomegalovirus lower matrix phosphoprotein 65(HCMV-pp65) in murine systemic lupus erythematosus(SLE).Methods:The prokaryotic plasmid pET-28b-pp65 was constructed to express the HCMVpp65 protein.BXSB mice and C57BL/6 mice were inoculated with pp65 eukarvotic plasmid pcDNA3.0-pp65 intramuscularly 5 times at 2-week intervals,and then the blood of the mice was subsequently collected via the retro-orbital vein.Indirect ELISAs were used to evaluate the concentration of anti-pp65 immunoglobulin G,anti-double-stranded DNA and antinuclear antibodies.lnterleukin-1β and tumor necrosis factor-α were also determined by competitive ELISA.At the same time,3 major SLE-related circulating microRNAs were examined by quantitative RT-PCR.Results:The early production of autoantibodies was observed in pp65-immunized male BXSB as well as C57BL/6 mice.Overexpression of interleukin-1β and tumor necrosis factor-a were detected in pp65-immunized male BXSB mice.Quantitative RT-PCR analyses showed that three SLE related microRNAs(microRNA-126,microRNA-125 a,and microRKA-146a) were dovvnrcgulatcd in peripheral blood mononuclear cells of pp65-immunizcd mice.Conclusions:Our findings indicate that HCMV-pp65 immunization strongly triggers the development and progression of" SLE-like disease in both BXSB and C57BL/6 mice,which indicates that the immune responses induced by HCMV-pp65 may be involved in the development of SLE.

Severe Acute Respiratory Syndrome-Retrospect and Lessons of 2004 Outbreak in China

Objective To summarize lessons learned from an outbreak of severe acute respiratory syndrome （SARS） in China during the spring of 2004. Methods Data of SARS cases were officially reported by Beijing Municipal Center for Disease Control and Prevention （BCDC） and Anhui Provincial Center for Disease Control and Prevention （APCDC） and results of epidemiological investigations were collected and analyzed. Results Three generations of 11 cases of SARS were identified during the outbreak, Initial two cases were most likely to be infected in Diarrhea Virus Laboratory of National Institute of Virology, China Centers for Disease Control and Prevention and main mode of transmission was direct contact with SARS patients, Delay in detecting initial case resulted in spread of the illness at hospitals and communities with two generations of secondary cases, Conclusions SARS outbreak in 2004 has yielded following lessons for public health globally. （1） Lab bio-safety programs should be made and should be strictly abided by, Studies in highly pathogenic viruses such as SARS coronavirus should be utmost cautious, （2） Management systems of occupational exposure to virus and disease surveillance need to be strengthened to take all risk factors into account so as to detect potential patients with infectious disease as early as possible.

Asymptomatic Norovirus Infection Among Children in Kindergartens and Primary Schools—Beijing Municipality,China,2021

Summary What is already known about this topic?Children in kindergartens and primary schools are the high-incidence groups of norovirus acute gastroenteritis.However,asymptomatic norovirus infection among them is seldom reported.What is added by this report?The norovirus positive rate was 3.48% among asymptomatic children in kindergartens and primary schools in Beijing Municipality in June 2021,the most common genotype was GII.4 Sydney,and no acute gastroenteritis outbreak was reported over the study period.

Neglected Aspects of SARS-CoV-2 Aerosol Transmission in Bathrooms of Multistory and High-Rise Buildings—Beijing Municipality,China,October 2022

Summary What is already known about this topic?There is a toilet flush-soil stack-floor drain pathway of aerosol transmission in multistory and high-rise buildings,but the influencing factors are not completely clear.What is added by this report?The poor airtightness of the connecting parts of the floor drain,as well as pressure fluctuations in the sewage pipe during toilet flushing caused by blockage of the soil stack vent,may lead to the cross-floor transmission of viral aerosols through the soil stack and floor drains.

An epidemiological analysis of the Beijing 2008 Hand-Foot-Mouth epidemic

This paper presents an empirical analysis of the epidemiological data concerning the 18445 HFMD-infected cases in Beijing in 2008.The main findings are as follows.(i) Seasonal variations in incidence were observed,with a peak observed during the summer season,especially in May.Male patients outnumber female patients by 1.57:1.(ii) Most cases occurred in children 4 years old or younger.Outperforming Weibull distribution and Gamma distribution as to model fitness when analyzing patient ages,log-normal distribution indicates that the estimated mean age is 3.4 years.(iii) The age distribution seems to indicate cyclic peaks with roughly one-year intervals.(iv) Correlation analyses (ρ=0.9864) show that time of birth in different months has an impact on the chance of being infected by HFMD.Birth month seems to present a high risk factor on infants and young children.(v) The morbidity rate is 132.7/100000 during the HFMD epidemic in Beijing in 2008.The morbidity map shows that the risks of HFMD infection in areas close to the city center and suburbans are much lower than those in the urban-rural transition zones.Spatial risks inferred from the morbidity map demonstrate a clear circular pattern.(vi) The prevention and control measures taken by the public health departments seem to be effective during the summer season,resulting in the early ending of the epidemic (one month earlier than the natural season) and reduced outbreak size.

Association of emergency room visits for respiratory diseases with sources of ambient PM2.5

Previous studies have reported associations of short-term exposure to different sources of ambient fine particulate matter(PM2.5)and increased mortality or hospitalizations for respiratory diseases.Few studies,however,have focused on the short-term effects of source-specific PM2.5 on emergency room visits(ERVs)of respiratory diseases.Source apportionment for PM2.5 was performed with Positive Matrix Factorization(PMF)and generalized additive model was applied to estimate associations between source-specific PM2.5 and respiratory disease ERVs.The association of PM2.5 and total respiratory ERVs was found on lag4(RR=1.011,95%CI:1.002,1.020)per interquartile range(76μg/m3)increase.We found PM2.5 to be significantly associated with asthma,bronchitis and chronic obstructive pulmonary disease(COPD)ERVs,with the strongest effects on lag5(RR=1.072,95%CI:1.024,1.119),lag4(RR=1.104,95%CI:1.032,1.176)and lag3(RR=1.091,95%CI:1.047,1.135),respectively.The estimated effects of PM2.5 changed little after adjusting for different air pollutants.Six primary PM2.5 sources were identified using PMF analysis,including dust/soil(6.7%),industry emission(4.5%),secondary aerosols(30.3%),metal processing(3.2%),coal combustion(37.5%)and traffic-related source(17.8%).Some of the sources were identified to have effects on ERVs of total respiratory diseases(dust/soil,secondary aerosols,metal processing,coal combustion and traffic-related source),bronchitis ERVs(dust/soil)and COPD ERVs(traffic-related source,industry emission and secondary aerosols).Different sources of PM2.5 contribute to increased risk of respiratory ERVs to different extents,which may provide potential implications for the decision making of air quality related policies,rational emission control and public health welfare.