Environmental Monitoring of A Laboratory for New Coronavirus Nucleic Acid Testing

The coronavirus disease 2019(COVID-19) is an infection of the respiratory tract which first broke out in Wuhan, China, in December 2019. The etiologic agent of this disease was identified as a betacoronavirus related to severe acute respiratory syndrome coronavirus(SARS-CoV). Thus, the International Committee on Virus Classification named the new coronavirus severe acute respiratory syndrome coronavirus-2(SARS-CoV-2)[1].

Environmental correlates of sedentary behaviors and physical activity in Chinese preschool children:A cross-sectional study

Objective:This cross-sectional study examined environmental correlates of sedentary behavior(SB) and physical activity(PA) in preschool children in the urban area of Tianjin,China.Methods:Data were collected from the Physical Activity and Health in Tianjin Chinese Children study,involving healthy children 3-6 years old and their families.In all children(n=980),leisure-time SB(LTSB) and leisure-time PA(LTPA) were reported in min/day by parents.In a subgroup(n=134),overall sedentary time,light PA,and moderate-to-vigorous PA(MVP A) were objectively measured using ActiGraph accelerometry(>3 days,>10 h/day).Environmental correlates were collected using a questionnaire that included home and neighborhood characteristics(e.g.,traffic safety,presence of physical activity facilities) and children’s behaviors.Potential correlates were identified using linear regression analysis.Results:Multiple linear regression analysis showed that "having grandparents as primary caregivers"(βs and 95% confidence intervals(95%CIs)for overall sedentary time:29.7(2.1-57.2);LTSB(In):0.19(0.11-0.28)) and "having a television(for LTSB(In):0.13(0.00-0.25)) or computer(for LTSB(ln):0.13(0.03-0.23) in the child’ s bedroom" were both associated with higher SB.Furthermore, "having grandparents as primary caregivers" was associated with less MVPA(β(95%CI):-7.6(-14.1 to-1.2)),and "active commuting to school by walking" correlated with more MVPA(β(95%CI):9.8(2.2-17.4)).The path model showed that "more neighborhood PA facilities close to home" was indirectly related to higher LTPA(In),which was partly mediated by "outdoor play"(path coefficients(95%CI):0.005(0.002-0.008)) and "going to these facilities more often"(path coefficients(95%CI):0.013(0.008-0.01 8)).Traffic safety was not a correlate.Conclusion:Family structure and media exposure in the home maybe important factors in shaping preschoolers’ PA patterns.Built environmental correlates could indirectly influence preschoolers’ LTPA through parental help with engaging in active behaviors.

Lifestyle improvement and the reduced risk of cardiovascular disease:the China-PAR project

BACKGROUND The benefits of healthy lifestyles are well recognized. However, the extent to which improving unhealthy lifestyles reduces cardiovascular disease(CVD) risk needs to be discussed. We evaluated the impact of lifestyle improvement on CVD incidence using data from the China-PAR project(Prediction for Atherosclerotic Cardiovascular Disease Risk in China).METHODS A total of 12,588 participants free of CVD were followed up for three visits after the baseline examination. Changes in four lifestyle factors(LFs)(smoking, diet, physical activity, and alcohol consumption) were assessed through questionnaires from the baseline to the first follow-up visit. Cox proportional hazard models were used to estimate hazard ratios(HRs) and corresponding 95% confidence intervals(CIs). The risk advancement periods(RAPs: the age difference between exposed and unexposed participants reaching the same incident CVD risk) and population-attributable risk percentage(PAR%) were also calculated.RESULTS A total of 909 incident CVD cases occurred over a median follow-up of 11.14 years. Compared with maintaining 0-1healthy LFs, maintaining 3–4 healthy LFs was associated with a 40% risk reduction of incident CVD(HR = 0.60, 95% CI: 0.45–0.79)and delayed CVD risk by 6.31 years(RAP:-6.31 [-9.92,-2.70] years). The PAR% of maintaining 3–4 unhealthy LFs was 22.0%compared to maintaining 0-1 unhealthy LFs. Besides, compared with maintaining two healthy LFs, improving healthy LFs from 2to 3–4 was associated with a 23% lower risk of CVD(HR = 0.77, 95% CI: 0.60–0.98).CONCLUSIONS Long-term sustenance of healthy lifestyles or improving unhealthy lifestyles can reduce and delay CVD risk.

Adverse effects of exposure to fine particles and ultrafine particles in the environment on different organs of organisms

Particulate pollution is a global risk factor that seriously threatens human health.Fine particles(FPs)and ultrafine particles(UFPs)have small particle diameters and large specific surface areas,which can easily adsorb metals,microorganisms and other pollutants.FPs and UFPs can enter the human body in multiple ways and can be easily and quickly absorbed by the cells,tissues and organs.In the body,the particles can induce oxidative stress,inflammatory response and apoptosis,furthermore causing great adverse effects.Epidemiological studies mainly take the population as the research object to study the distribution of diseases and health conditions in a specific population and to focus on the identification of influencing factors.However,the mechanism by which a substance harms the health of organisms is mainly demonstrated through toxicological studies.Combining epidemiological studies with toxicological studies will provide a more systematic and comprehensive understanding of the impact of PM on the health of organisms.In this review,the sources,compositions,and morphologies of FPs and UFPs are briefly introduced in the first part.The effects and action mechanisms of exposure to FPs and UFPs on the heart,lungs,brain,liver,spleen,kidneys,pancreas,gastrointestinal tract,joints and reproductive system are systematically summarized.In addition,challenges are further pointed out at the end of the paper.This work provides useful theoretical guidance and a strong experimental foundation for investigating and preventing the adverse effects of FPs and UFPs on human health.

Associations of tea consumption with blood pressure progression and hypertension incidence

BACKGROUND Association between tea consumption and incident hypertension remains uncertain.This study conducted to examine the health effects of tea consumption on blood pressure progression and hypertension incidence.METHODS A population-based cohort of 38,913 Chinese participants without hypertension at baseline were included in the current study.Information on tea consumption was collected through standardized questionnaires.Associations of tea consump-tion with blood pressure progression and incident hypertension were analyzed using logistic regression models and Cox propor-tional hazards regression models,respectively.RESULTS During a median follow-up of 5.9 years,17,657 individuals had experienced progression to a higher blood pressure stage and 5,935 individuals had developed hypertension.In multivariate analyses,habitual tea drinkers(≥3 times/week for at least six months)had a 17%lower risk for blood pressure progression[odds ratio(OR)=0.83,95%CI:0.79-0.88]and a 14%de-creased risk for incident hypertension[hazard ratio(HR)=0.86,95%CI:0.80-0.91]compared with non-habitual tea drinkers.In-dividuals in different baseline blood pressure groups could obtain similar benefit from habitual tea drinking.In terms of tea con-sumption amount,an inverse,linear dose-response relation between monthly consumption of tea leaves and risk of blood pres-sure progression was observed,while the risk of incident hypertension did not reduce further after consuming around 100 g of tea leaves per month.CONCLUSIONS Our study demonstrated that habitual tea consumption could provide preventive effect against blood pres-sure progression and hypertension incidence.

Association between Pre-pregnancy Body Mass Index and Offspring Neuropsychological Development from 1 to 24 Months of Age: A Birth Cohort Study in China

Objective To explore the interactions between pre-pregnancy body mass index(BMI) and age on offspring neuropsychological development from 1 to 24 months in China.Methods In this birth cohort study, a total of 2,253 mother-child pairs were enrolled in Tianjin, China,between July 2015 and May 2018. The China Developmental Scale for Children was used to assess developmental quotient(DQ) of children aged from 1 to 24 months.Results Mixed-models analysis revealed significant age × pre-pregnancy BMI interactions for total DQ and five neurobehavioral domains(gross motor, fine motor, adaptive, language, and social;P < 0.001).Age × pre-pregnancy BMI ≥ 25 kg/m^2 was associated with a negative effect on total DQ and five neurobehavioral domains, as compared to pre-pregnancy BMI < 25 kg/m^2(P < 0.01). Multiple comparisons showed pre-pregnancy BMI ≥ 25 kg/m^2 of mothers had a positive effect on child total DQ at the age of 1 month but a negative effect at 24 months(P < 0.05).Conclusions This study supported the age × pre-pregnancy BMI interaction on offspring neuropsychological development. It also revealed a short-term positive impact of high pre-pregnancy BMI on neuropsychological development at 1 month of age, but a long-term negative effect(from 1 to24 months).

Effects of the total physical activity and its changes on incidence, progression, and remission of hypertension

OBJECTIVES Moderate to vigorous physical activity is recommended to prevent hypertension according to the current guidelines.However,the degree to which the total physical activity(TPA)and its changes benefit normotensives and hypertensives is uncertain.We aimed to examine the effects of TPA and its changes on the incidence,progression,and remission of hypertension in the large-scale prospective cohorts.METHODS A total of 73,077 participants(55,101 normotensives and 17,976 hypertensives)were eligible for TPA analyses.During a mean follow-up of 7.16 years(394,038 person-years),12,211 hypertension cases were identified.TPA was estimated as metabolic equivalents and categorized into quartiles.Cox proportional hazards regression and multivariable logistic regression were used to estimate associations of TPA and changes in TPA with incident hypertension and progression/remission of hypertension.RESULTS Compared with the lowest quartile of TPA,normotensives at the third and the highest quartile had a decreased risk of incident hypertension,with hazard ratios(HRs)of 0.86[95%confidence interval(CI):0.81−0.91]and 0.81(95%CI:0.77−0.86),respectively.Hypertensives at the highest quartile of TPA demonstrated a decreased risk of progression of hypertension[odds ratio(OR)=0.87,95%CI:0.79−0.95],and an increased probability of hypertension remission(OR=1.17,95%CI:1.05−1.29).Moreover,getting active from a sedentary lifestyle during the follow-up period could reduce 25%(HR=0.75,95%CI:0.58−0.96)risk of incident hypertension,whereas those becoming sedentary did not achieve benefit from initially being active.CONCLUSIONS Our findings indicated that increasing and maintaining TPA levels could benefit normotensives,whereas higher TPA levels were needed to effectively control progression and improve remission of hypertension.Physical activity played undoubtedly an essential role in both primary and secondary prevention of hypertension.

Association between Fruit and Vegetable Intake and Arterial Stiffness: The China-PAR Project

Objective This study aimed to investigate the association between fruit and vegetable intake and arterial stiffness.Methods We conducted a cohort-based study comprising 6,628 participants with arterial stiffness information in the Prediction for Atherosclerotic Cardiovascular Disease Risk in China(China-PAR)project. A semi-quantitative food-frequency questionnaire was used to assess baseline(2007–2008) and recent(2018–2021) fruit and vegetable intake. We assessed changes in fruit and vegetable intake from2007–2008 to 2018–2021 in 6,481 participants. Arterial stiffness was measured using the arterial velocity–pulse index(AVI) and arterial pressure-volume index(API). Elevated AVI and API values were defined according to diverse age reference ranges.Results Multivariable-adjusted linear regression models revealed that every 100 g/d increment in fruit and vegetable intake was associated with a 0.11 decrease in AVI(B =-0.11;95% confidence interval [CI]:-0.20,-0.02) on average, rather than API(B = 0.02;95% CI:-0.09, 0.13). The risk of elevated AVI(odds ratio [OR] = 0.82;95% CI: 0.70, 0.97) is 18% lower in individuals with high intake(≥ 500 g/d) than in those with low intake(< 500 g/d). Furthermore, maintaining a high intake in the past median of 11.5years of follow-up was associated with an even lower risk of elevated AVI compared with a low intake at both baseline and follow-up(OR = 0.64;95% CI: 0.49, 0.83).Conclusion Fruit and vegetable intake was negatively associated with arterial stiffness, emphasizing recommendations for adherence to fruit and vegetable intake for the prevention of arterial stiffness.

Economic Evaluation of the Comprehensive AIDS Prevention and Control Program—Tianjin Municipality,China,2011-2022

What is already known about this topic?Acquired immunodeficiency syndrome(AIDS)represents a significant public health challenge globally,not only inflicting harm on the health of individuals but also placing a considerable economic strain on society.What is added by this report?This study represents the inaugural report on the potential reduction in economic burden attributable to human immunodeficiency virus(HIV)prevention strategies in Tianjin.Between 2011 and 2022,it is estimated that effective measures could prevent 2,965 new HIV infections and avert 658 deaths,resulting in an economic benefit of approximately 14.437 billion Chinese Yuan.What are the implications for public health practice?The findings of this study offer valuable evidence to inform the development of localized HIV prevention and control strategies,as well as to guide public health policymaking.

Changes in muscle strength and risk of cardiovascular disease among middle-aged and older adults in China:Evidence from a prospective cohort study

Background:Evidence indicates that low muscle strength is associated with an increased cardiovascular diseases(CVDs)risk.However,the association between muscle strength changes based on repeated measurements and CVD incidence remains unclear.Methods:The study used data from the China Health and Retirement Longitudinal Study in 2011(Wave 1),2013(Wave 2),2015(Wave 3),and 2018(Wave 4).Low muscle strength was defined as handgrip strength<28 kg for men or<18 kg for women,or chair-rising time≥12 s.Based on changes in muscle strength from Waves 1 to 2,participants were categorized into four groups of Normal-Normal,Low-Normal,Normal-Low,and Low-Low.CVD events,including heart disease and stroke,were recorded using a self-reported questionnaire during Waves 3 and 4 visits.Cox proportional hazards models were used to investigate the association between muscle strength changes and CVD incidence after multivariable adjustments.Hazard ratios(HRs)and 95%confidence intervals(95%CIs)were estimated with the Normal-Normal group as the reference.Results:A total of 1164 CVD cases were identified among 6608 participants.Compared to participants with sustained normal muscle strength,the CVD risks increased progressively across groups of the Low-Normal(HR=1.20,95%CI:1.01-1.43),the Normal-Low(HR=1.35,95%CI:1.14-1.60),and the Low-Low(HR=1.76,95%CI:1.49-2.07).Similar patterns were observed for the significant associations between muscle strength status and the incidence risks of heart disease and stroke.Subgroup analyses showed that the significant associations between CVD and muscle strength changes were consistent across age,sex,and body mass index(BMI)categories.Conclusions:The study found that muscle strength changes were associated with CVD risk.This suggests that continuous tracking of muscle status may be helpful in screening cardiovascular risk.

Maternal serum branched-chain amino acids in early pregnancy and offspring growth patterns from 1 year to 8 years of age

to persist into adulthood and be associated with many adverse health outcomes later in adulthood,including cardiovascular diseases and type 2 diabetes.[1]In utero exposure to“undernutrition”or“over-nutrition”plays an important role in obesity in childhood and diseases in adulthood.[2]It is established that high branchedchain amino acids(BCAAs)are associated with insulin resistance and gestational diabetes mellitus(GDM).[3]However,it is largely unknown whether in utero exposure to high BCAAs also plays a role in adverse childhood growth patterns.We used 8-year children follow-up data of a case-control study nested within a population-based prospective cohort of pregnant women in Tianjin,China,to examine associations between maternal BCAAs levels in early pregnancy and obesity-related growth patterns if any,in offspring at 1-8 years of age.

Psychosocial Stress Modifies the Acute Cardiac Health Effects of Traffic-Related Air Pollution

Previous studies have shown that exposure to black carbon(BC,a tracer of traffic-related air pollution)and psychosocial stress are both associated with adverse cardiac effects,but whether psychosocial stress could modify the cardiac effects of BC is unclear.To investigate the potential modifying effect of psychosocial stress on the associations between acute exposure to BC and typical cardiac health variables,real-time personal 24 h measurements were conducted in a repeated-measure study among adults with elevated blood pressure(high-risk group)and a panel study among normal adults(low-risk group)in China.Measured cardiac health variables included ST-segment depression events,heart rate,and heart rate variability(HRV)variables.Perceived Stress Scale,State Anxiety Inventory and Self-rating Depression Scale were used to assess the recent psychosocial stress status of the participants,and a composite stress index was established based on these scales.Generalized linear mixed-effects model was used to analyze the associations between BC exposure and cardiac health variables and potential effect modification by psychosocial stress.A total of 9724 h measurements among 97 participants in the repeated-measure study and 20224 h measurements among 87 participants in the panel study were included in the final analysis.Acute BC exposure was significantly associated with increased ST-segment depression events and heart rate and decreases in HRV in both studies.The marginal effects of acute BC exposure on most cardiac health variables generally tended to be amplified under higher vs low levels of psychosocial stress in both studies,with the composite stress index apparently modifying the associations of BC exposure with most ST-segment depression events and HRV variables.These findings suggest that psychosocial stress may increase the participants’cardiac susceptibility to BC exposure,which could be helpful for the identification of susceptible individuals in the context of traffic-related air pollution.

Long-term exposure to fine particulate matter modifies the association between physical activity and hypertension incidence

Background:The trade-off between the benefits of regular physical activity(PA)and the potentially detrimental effects of augmented exposure to air pollution in highly polluted regions remains unclear.This study aimed to examine whether ambient fine particulate matter(PM_(2.5))exposure modified the impacts of PA volume and intensity on hypertension risk.Methods:We included 54,797 participants without hypertension at baseline in a nationwide cohort of the Prediction for Atherosclerotic Cardiovascular Disease Risk in China(China-PAR)project.PA volume and intensitywere assessed by questionnaire,and high-resolution(1 km×1 km)PM_(2.5)estimates were generated using a satellite-based model.Results:During 413,516 person-years of follow-up,12,100 incident hypertension cases were identified.PM_(2.5)significantly modified the relationship between PA and hypertension incidence(p_(interaction)<0.001).Increased PA volume was negatively associated with incident hypertension in the low PM_(2.5)stratum(<59.8μg/m^(3),ptrend<0.001),with a hazard ratio of 0.81(95%confidence interval(95%CI):0.74-0.88)when comparing the fourth with the first quartile of PA volume.However,the health benefits were not observed in the high PM_(2.5)stratum(≥59.8μg/m^(3),p_(trend)=0.370).Moreover,compared with light PA intensity,vigorous intensity was related to a 20%(95%CI:9%-29%)decreased risk of hypertension for participants exposed to low PM_(2.5),but a 17%(95%CI:4%-33%)increased risk for those with high PM_(2.5)levels.Conclusion:PA was associated with a reduced risk of hypertension only among participants with low PM_(2.5)exposure.Our findings recommended regular PA to prevent hypertension in less polluted regions and reinforced the importance of air quality improvement.

Physical activity, long-term fine particulate matter exposure and type 2 diabetes incidence: A prospective cohort study

Background: Despite the adverse effects of ambient fine particulate matter (PM_(2.5) ) on type 2 diabetes and the beneficial role of physical activity (PA), the influence of PM_(2.5) on the relationship between PA and type 2 diabetes remains unclear.Methods: In this prospective study with 71,689 participants, PA was assessed by a questionnaire and was categorized into quartiles for volume and three groups for intensity. Long-term PM_(2.5) exposure was calculated using 1-km resolution satellite-based PM_(2.5) estimates. PM_(2.5) exposure and PA's effect on type 2 diabetes were assessed by cohort-stratified Cox proportional hazards models, individually and in combination.Results: In 488,166 person-years of follow-up, 5487 incident type 2 diabetes cases were observed. The association between PA and type 2 diabetes was modified by PM_(2.5) . Compared with the lowest quartile of PA volume, the highest quartile was associated with reduced type 2 diabetes risk in low PM_(2.5) stratification (≤65.02 μg/m^(3)) other than in high PM_(2.5) stratification (>65.02 μg/m^(3)), with the hazard ratio (HR) of 0.75 (95% confidence interval [CI]: 0.66-0.85) and 1.10 (95% CI: 0.99-1.22), respectively. Similar results were observed for PA intensity. High PM_(2.5) exposure combined with the highest PA levels increased the risk of type 2 diabetes the most (HR= 1.79, 95% CI: 1.59-2.01 for PA volume;HR = 1.82, 95% CI: 1.64-2.02 for PA intensity).Conclusion: PA could reduce type 2 diabetes risk in low-pollution areas, but high PM_(2.5) exposure may weaken or even reverse the protective effects of PA. Safety and health benefits of PA should be thoroughly assessed for long-term polluted residents.

Association between Long-Term Exposure to PM_(2.5) Inorganic Chemical Compositions and Cardiopulmonary Mortality: A 22-Year Cohort Study in Northern China

Particulate matter with diameters≤2.5μm(PM_(2.5))has been identified as a significant air pollutant contributing to premature mortality.Nevertheless,the specific compositions within PM_(2.5) that play the most crucial role remain unclear,especially in areas with high pollution concentrations.This study aims to investigate the individual and joint mortality risks associated with PM_(2.5) inorganic chemical compositions and identify primary contributors.In 1998,we conducted a prospective cohort study in four northern Chinese cities(Tianjin,Shenyang,Taiyuan,and Rizhao).Satellite-based machine learning models calculated PM_(2.5) inorganic chemical compositions,including sulfate(SO_(4)^(2–)),nitrate(NO_(3)^(–)),ammonium(NH_(4)^(+)),and chloride(Cl^(-)).A time-varying Cox proportional hazards model was applied to analyze associations between these compositions and cardiorespiratory mortality,encompassing nonaccidental causes,cardiovascular diseases(CVDs),nonmalignant respiratory diseases(RDs),and lung cancer.The quantile-based g-computation model evaluated joint exposure effects and relative contributions of the compositions.Stratified analysis was used to identify vulnerable subpopulations.During 785,807 person-years of follow-up,5812(15.5%)deaths occurred from nonaccidental causes,including 2932(7.8%)from all CVDs,479(1.3%)from nonmalignant RDs,and 552(1.4%)from lung cancer.Every interquartile range(IQR)increase in SO_(4)^(2–)was associated with mortality from nonaccidental causes(hazard ratio:1.860;95%confidence interval:1.809,1.911),CVDs(1.909;1.836,1.985),nonmalignant RDs(2.178;1.975,2.403),and lung cancer(1.773;1.624,1.937).In the joint exposure model,a simultaneous rise of one IQR in all four compositions increased the risk of cardiorespiratory mortality by at least 36.3%,with long-term exposure to SO_(4)^(2–)contributing the most to nonaccidental and cardiopulmonary deaths.Individuals with higher incomes and lower education levels were found to be more vulnerable.Long-term exposure to higher levels of PM_(2.5) inorganic compositions was associated with significantly increased cardiopulmonary mortality,with SO_(4)^(2–)potentially being the primary contributor.These findings offer insights into how PM_(2.5) sources impact health,aiding the development of more effective governance measures.

Impacts of PM_(2.5) on Ambulatory Blood Pressure Monitoring Indicators Attenuated by Blood Pressure Control Status and Treatment-Two Cities and Two Municipalities,China,2017−2019

Summary What is already known about this topic?Short-term PM_(2.5) exposure has been associated with hourly,24-hour,daytime,and nighttime blood pressure(BP)levels,and further studies focusing whether and how the associations with other ambulatory BP monitoring indicators are warranted.

Fruit and vegetable consumption,cardiovascular disease,and all-cause mortality in China

Evidence about the response patterns of fruit and vegetable consumption with the risk of cardiovascular disease(CVD)and allcause mortality was inconsistent.These associations were examined using a large-scale,population-based Chinese cohort comprising 100,728 participants.A food-frequency questionnaire was used to assess fruit and vegetable consumption.Outcomes were ascertained by interviewing individuals or their proxies and checking hospital records or death certificates.Cox proportional hazards regression was used to calculate hazard ratios(HRs)with 95% confidence intervals(CIs).At the 736,668 person-years of follow-up,3,677 CVD cases and 5,466 deaths were identified.The multivariable-adjusted HRs for CVD across increasing quartiles of total fruit and vegetable consumption were 1(reference),0.94(95%CI=0.85-1.04),0.89(95%CI=0.80-0.98),and 0.85(95%CI=0.77-0.95).Moreover,participants in the highest quartile displayed a 13% lower risk of all-cause mortality(HR=0.87;95%CI=0.80-0.95).A nonlinear dose-response relation was found for CVD,without additional benefits beyond a consumption of600 g d-1,whereas the all-cause mortality risk decreased along with higher consumption,with a linear trend.These associations remained significant for fruit consumption but not for vegetable consumption.Our findings indicated that greater fruit and vegetable consumption was significantly associated with a lower risk of CVD and all-cause mortality.Increasing fruit and vegetable consumption,especially fruit,in the general population would prevent CVD and premature mortality.

Ambient Ozone Exposure, Semen Plasma Metabolites, and Sperm Quality Decline among Adult Men in Wuhan China

Ambient ozone(O3)exposure may be associated with a reduction of semen quality,yet the potential biological mechanisms remain unclear.We investigated the effects of certain seminal plasma metabolites on mediating the links between O3 exposure and the deterioration of semen quality.The untargeted metabolomics analysis was performed on semen samples of 200 Chinese adult men to determine candidate metabolites associated with characteristics of semen quality.Mediation analysis was adopted to examine whether these metabolites modulated the links between O3 exposure and semen quality.We found a significant reduction in sperm concentration by−28.1%(95%CI:−41.7%,−11.3%),and sperm count by−29.2%(95%CI:−43.7%,−11.0%)associated with each 10μg/m3 increase in ambient O3 concentration during the period of sperm development.We delineated 7 metabolites in seminal fluid that substantially mediated the links between O3 exposure and declined semen quality,including myristoleic acid,aspartyl-isoleucine,phenylethyl primeveroside,ACar(18:2),ACar(18:1),FAHFA(22:6/22:3),and LPS(22:5).Among these,myristoleic acid exhibited the most pronounced mediation effects,with its indirect effect of which accounts for 46.4%of the overall association.Our findings suggested that exposure to ozone decreased sperm quality by disrupting fatty acid metabolism,particularly myristoleic acid.