Background: With the increasing occurrence of extreme temperature events due to climate change, the attention has been predominantly focused on the effects of heat waves and cold spells on morbidity and mortality. However, the influence of these temperature extremes on blood parameters has been overlooked.

Methods: We conducted a cohort study involving 2,752 adult blood donors in Tianjin, China, between January 18, 2013, and June 25, 2021. The generalized additive mixed model was used to investigate the effects and lagged effects of heat waves and cold spells on six blood parameters of blood donors, including alanine aminotransferase (ALT), white blood cell count (WBC), red blood cell count (RBC), hemoglobin (HB), hematocrit (HCT), and platelet count (PLT). Subgroup analyses were stratified by sex, age, and BMI.

Results: Heat waves and cold spells are associated with changes in blood parameters, particularly HB and PLT. Heat waves increased HB and PLT, while cold spells increased HB and decreased PLT. The effect of heat waves is greater than that of cold spells. The largest effect of heat waves on HB and PLT occurred at lag1 with 2.6 g/L (95% CI: 1.76 to 3.45) and lag7 with 9.71 × 10^9/L (95% CI: 6.26 to 13.17), respectively, while the largest effect of cold spells on HB and PLT occurred at lag0 with 1.02 g/L (95% CI: 0.71 to 1.33) and lag2 with −3.85 × 10^9/L (95% CI: −5.00 to −2.70), respectively. In subgroup analysis, the effect of cold spells on ALT was greater in the 40–49 age group.

Conclusion: We indicated that heat waves and cold spells can impact hemoglobin and platelet counts in the human body. These findings provide evidence linking heat waves or cold spells to diseases and may reduce health risks caused by extreme temperature events.

Background: Air pollution and a number of metabolic disorders have been reported to increase the risk of severe COVID-19 outcomes. This study explored the association between severe COVID-19 outcomes, metabolic disorders and environmental air pollutants, at regional level, across 38 countries.

Methods: We conducted an ecological study using COVID-19 data related to countries of the Organization for Economic Cooperation and Development (OECD), with an estimated population of 1.4 billion. They were divided into 3 regions: 1. Europe & Middle east; 2. Americas (north, central & south America); 3. East-Asia & West Pacific. The outcome variables were: COVID-19 case-fatality rate (CFR) and disability-adjusted life years (DALYs) at regional level. Freely accessible datasets related to regional DALYs, demographics and other environmental pollutants were obtained from OECD, WHO and the World in Data websites. Generalized linear model (GLM) was performed to determine the regional determinants of COVID-19 CFR and DALYs using the aggregate epidemiologic data (Dec. 2019–Dec. 2021).

Results: Overall cumulative deaths were 65,000 per million, for mean CFR and DALYs of 1.31 (1.2)% and 17.35 (2.3) years, respectively. Globally, GLM analysis with adjustment for elderly population rate, showed that COVID-19 CFR was positively associated with atmospheric PM_2.5 level (beta = 0.64(0.0), 95%CI: 0.06–1.35; p < 0.05), diabetes prevalence (beta = 0.26(0.1), 95%CI: 0.12–0.41; p < 0.001). For COVID-19 DALYs, positive associations were observed with atmospheric NOx level (beta = 0.06(0.0), 95%CI: 0.02–0.82; p < 0.05) and diabetes prevalence (beta = 0.32(0.2), 95%CI: 0.04–0.69; p < 0.05). At regional level, adjusted GLM analysis showed that COVID-19 CFR was associated with atmospheric PM_2.5 level in the Americas and East-Asia & Western Pacific region; it was associated with diabetes prevalence for countries of Europe & Middle east and East-Asia & Western Pacific region. Furthermore, COVID-19 DALYs were positively associated with atmospheric PM_2.5 and diabetes prevalence for countries of the Americas only.

Conclusion: These findings confirm that diabetes and air pollution increase the risk of disability and fatality due to COVID-19, with disparities in terms of their impact. They suggest that efficient preventive and management programs for diabetes and air pollution countermeasures would have curtailed severe COVID-19 outcome rates.

Background: Few prospective cohort studies have examined the association between maternal diabetes, including pre-pregnancy and gestational diabetes, and the risk of congenital heart disease (CHD) in Asian offspring.

Methods: We examined the association between maternal diabetes and offspring CHD among 97,094 mother-singleton infant pairs in the Japan Environment and Children’s Study (JECS) between January 2011 and March 2014. Odds ratios (OR) and 95% confidence intervals (CI) of offspring CHD based on maternal diabetes (pre-pregnancy diabetes and gestational diabetes) were estimated using logistic regression after adjusting for maternal age at delivery, pre-pregnancy body mass index (BMI), maternal smoking habits, alcohol consumption, annual household income, and maternal education. The diagnosis of CHD in the offspring was ascertained from the transcript of medical records.

Results: The incidence of CHD in the offspring was 1,132. Maternal diabetes, including both pre-pregnancy diabetes and gestational diabetes, was associated with a higher risk of offspring CHD: multivariable OR (95%CI) = 1.81 (1.40–2.33) for maternal diabetes, 2.39 (1.05–5.42) for pre-pregnancy diabetes and 1.77 (1.36–2.30) for gestational diabetes. A higher risk of offspring CHD was observed in pre-pregnancy BMI ≥25.0 kg/m² (OR = 2.55, 95% CI: 1.74–3.75) than in pre-pregnancy BMI <25.0 kg/m² (OR = 1.49, 95% CI: 1.05–2.10, p for interaction = 0.04).

Conclusions: Maternal diabetes, including both pre-pregnancy and gestational, was associated with an increased risk of CHD in offspring.

Background: The application of metabolomics-based profiles in environmental epidemiological studies is a promising approach to refine the process of health risk assessment. We aimed to identify potential metabolomics-based profiles in urine and plasma for the detection of relatively low-level cadmium (Cd) exposure in large population-based studies.

Method: We analyzed 123 urinary metabolites and 94 plasma metabolites detected in fasting urine and plasma samples collected from 1,412 men and 2,022 women involved in the Tsuruoka Metabolomics Cohort Study. Regression analysis was performed for urinary N-acetyl-beta-D-glucosaminidase (NAG), plasma, and urinary metabolites as dependent variables, and urinary Cd (U-Cd, quartile) as an independent variable. The multivariable regression model included age, gender, systolic blood pressure, smoking, rice intake, BMI, glycated hemoglobin, low-density lipoprotein cholesterol, alcohol consumption, physical activity, educational history, dietary energy intake, urinary Na/K ratio, and uric acid. Pathway-network analysis was carried out to visualize the metabolite networks linked to Cd exposure.

Result: Urinary NAG was positively associated with U-Cd, but not at lower concentrations (Q2). Among urinary metabolites in the total population, 45 metabolites showed associations with U-Cd in the unadjusted and adjusted models after adjusting for the multiplicity of comparison with FDR. There were 12 urinary metabolites which showed consistent associations between Cd exposure from Q2 to Q4. Among plasma metabolites, six cations and one anion were positively associated with U-Cd, whereas alanine, creatinine, and isoleucine were negatively associated with U-Cd. Our results were robust by statistical adjustment of various confounders. Pathway-network analysis revealed metabolites and upstream regulator changes associated with mitochondria (ACACB, UCP2, and metabolites related to the TCA cycle).

Conclusion: These results suggested that U-Cd was associated with metabolites related to upstream mitochondrial dysfunction in a dose-dependent manner. Our data will help develop environmental Cd exposure profiles for human populations.

Background: Perfluorooctanoic acid (PFOA) is one of the major per- and polyfluoroalkyl substances. The role of ATP-binding cassette (ABC) transporters in PFOA toxicokinetics is unknown.

Methods: In this study, two ABC transporters, ABCB1 and ABCB4, were examined in mice with single intravenous PFOA administration (3.13 µmol/kg). To identify candidate renal PFOA transporters, we used a microarray approach to evaluate changes in gene expression of various kidney transporters in Abcb4 null mice.

Results: Biliary PFOA concentrations were lower in Abcb4 null mice (mean ± standard deviation: 0.25 ± 0.12 µg/mL) than in wild-type mice (0.87 ± 0.02 µg/mL). Immunohistochemically, ABCB4 expression was confirmed at the apical region of hepatocytes. However, renal clearance of PFOA was higher in Abcb4 null mice than in wild-type mice. Among 642 solute carrier and ABC transporters, 5 transporters showed significant differences in expression between wild-type and Abcb4 null mice. These candidates included two major xenobiotic transporters, multidrug resistance 1 (Abcb1) and organic anion transporter 3 (Slc22a8). Abcb1 mRNA levels were higher in Abcb4 null mice than in wild-type mice in kidney. In Abcb4 null mice, Abcb1b expression was enhanced in proximal tubules immunohistochemically, while that of Slc22a8 was not. Finally, in Abcb1a/b null mice, there was a significant decrease in the renal clearance of PFOA (0.69 ± 0.21 vs 1.1 mL ± 0.37/72 h in wild-type mice). A homology search of ABCB1 showed that several amino acids are mutated in humans compared with those in rodents and monkeys.

Conclusions: These findings suggest that, in the mouse, Abcb4 and Abcb1 are excretory transporters of PFOA into bile and urine, respectively.

Background: Non-optimum temperatures are associated with increased risk of respiratory diseases, but the effects of apparent temperature (AT) on respiratory diseases remain to be investigated.

Methods: Using daily data from 2016 to 2020 in Ganzhou, a large city in southern China, we analyzed the impact of AT on outpatient and inpatient visits for respiratory diseases. We considered total respiratory diseases and five subtypes (influenza and pneumonia, upper respiratory tract infection (URTI), lower respiratory tract infection (LRTI), asthma and chronic obstructive pulmonary disease [COPD]). Our analysis employed a distributed lag nonlinear model (DLNM) combined with a generalized additive model (GAM).

Results: We recorded 94,952 outpatients and 72,410 inpatients for respiratory diseases. We found AT significantly non-linearly associated with daily outpatient and inpatient visits for total respiratory diseases, influenza and pneumonia, and URTI, primarily during comfortable AT levels, while it was exclusively related with daily inpatient visits for LRTI and COPD. Moderate heat (32.1 °C, the 75.0th centile) was observed with a significant effect on both daily outpatient and inpatient visits for total respiratory diseases at a relative risk of 1.561 (1.161, 2.098) and 1.276 (1.027, 1.585), respectively (both P < 0.05), while the results of inpatients became insignificant with the adjustment for CO and O₃. The attributable fractions in outpatients and inpatients were as follows: total respiratory diseases (24.43% and 18.69%), influenza and pneumonia (31.54% and 17.33%), URTI (23.03% and 32.91%), LRTI (37.49% and 30.00%), asthma (9.83% and 3.39%), and COPD (30.67% and 10.65%). Stratified analyses showed that children ≤5 years old were more susceptible to moderate heat than older participants.

Conclusions: In conclusion, our results indicated moderate heat increase the risk of daily outpatient and inpatient visits for respiratory diseases, especially among children under the age of 5.

Background: Although longer working hours are associated with lower sleep quality, it is still necessary to work a certain number of hours to make a living. In this study, we investigated the relationship between working hours and sleep quality in a community setting. We then explored how to manage work style while maintaining the sleep quality of workers without markedly reducing working hours.

Methods: 4388 day-time workers in various occupations living in Ota ward in Tokyo were included in the analysis. The relationship between working hours and sleep quality measured by the Athens Insomnia Scale was examined by ANOVA and linear regression models. Effect modification by work style (work end time, shift in working start and end time, current work from home status, change in work place) on the relationship between working hours and sleep quality was investigated by multivariate linear regression models.

Results: Longer working hours were significantly associated with lower sleep quality. The magnitude of the relationship between long working hours and low sleep quality was significantly larger when work end time was later (p for trend of interaction < 0.01) and when working start and end time were shifted later (vs no change, p for interaction = 0.03). The relationship was marginally greater when the proportion of work from home was increased (vs no change, p for interaction = 0.07).

Conclusions: A relationship between longer working hours and lower sleep quality was observed among workers. Leaving work earlier or optimizing the work environment at home may diminish the adverse effect of long working hours on sleep quality.

Background: Social relationships are essential in maintaining the physical and mental health of mothers and their children. However, there is limited evidence on how social support provided to the mother during pregnancy could impact child development. Herein, we examined whether maternal social support levels during pregnancy was associated with the risk of developmental delay in 3-year-old children.

Methods: Overall, 68,442 mother-child pairs completed questionnaires on maternal social support during pregnancy and development delay in 3-year-old children. The maternal social support level was evaluated using four items. The risk of development delay was evaluated using the Japanese version of the Ages and Stages Questionnaire-3 (ASQ-3) with five domains of communication, gross motor, fine motor, problem-solving, and personal-social. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using logistic regression according to the quintiles of maternal social support levels after adjusting for potential confounding factors.

Results: Social support during pregnancy was associated with a lower risk of development delay at 3 years of age. Beneficial effects were detected in all domains of the ASQ-3 (p for trend <0.001). Multivariable ORs (95% CIs) for the highest versus lowest quartiles of maternal social support level were 0.57 (0.50–0.65) for communication, 0.49 (0.43–0.55) for gross motor delay, 0.58 (0.53–0.64) for fine motor delay, 0.56 (0.51–0.62) for problem-solving delay, and 0.52 (0.45–0.60) for personal social delay. The associations remained unchanged when stratified by maternal education level, paternal education level, living with children, household income, and postpartum depression.

Conclusion: Maternal social support during pregnancy was inversely associated with the risk of developmental delay at 3 years of age.

Background: Air pollution-induced systemic inflammation and oxidative stress are hypothesized to be the major biological mechanisms underlying pathological outcomes. We examined the association between short-term exposure to ambient air pollutants and biomarkers of inflammation and oxidative stress in 2199 general middle-aged Korean population residing in metropolitan areas.

Methods: Serum levels of inflammatory cytokines (interleukin [IL]-1β, IL-6, IL-8, IL-10, and tumor necrosis factor [TNF]-α) and urinary levels of 8-hydroxy-2′-deoxyguanosine (8-OHdG) were measured. Daily concentrations of a series of air pollutants (particulate matter [PM]₁₀, PM_2.5, SO₂, NO₂, CO, and O₃) were predicted using the Community Multiscale Air Quality modeling system, and participant-level pollutant exposure was determined using geocoded residential addresses. Short-term exposure was defined as the 1- to 7-day moving averages.

Results: The multivariable-adjusted linear models controlling for the sociodemographic, lifestyle, temporal, and meteorological factors identified positive associations of PM with IL-1β, IL-8, IL-10, TNF-α, and 8-OHdG levels; SO₂ with IL-10 levels, CO with IL-1β, IL-10, and TNF-α levels; and O₃ with IL-1β, IL-8, and 8-OHdG levels. O₃ levels were inversely associated with IL-10 levels. For each pollutant, the strongest associations were observed for the 7-day average PM and CO with IL-1β (per 10-µg/m³ increase in PM₁₀: 2.7%, 95% confidence interval [CI] = 0.6–4.8; per 10-µg/m³ increase in PM_2.5: 6.4%, 95% CI = 2.4–10.5; per 0.1-ppm increase in CO: 3.3%, 95% CI = 0.3–6.5); the 2-day average SO₂ with IL-10 levels (per 1-ppb increase in SO₂: 1.1%, 95% CI = 0.1–2.1); and the 7-day average O₃ with IL-8 levels (per 1-ppb increase in O₃: 1.3%, 95% CI = 0.7–1.9).

Conclusions: Short-term exposure to ambient air pollutants may induce oxidative damage and pro-inflammatory roles, together with counter-regulatory anti-inflammatory response.

Background: Excessive screen time (ST) in children is a global concern. We assessed the association between individual- and school-level factors and excessive ST in Japanese children using a multilevel analysis.

Methods: A school-based cross-sectional study was conducted in Toyama, Japan in 2018. From 110 elementary schools in Toyama Prefecture, 13,413 children in the 4th-6th grades (boys, 50.9%; mean, 10.5 years old) participated. We assessed lifestyle, recreational ST (not for study use), psychological status, and school and family environment including family rules. We defined ≥3 hours ST as excessive. We calculated the school-level proportions of no family rules and divided them into four categories (<20%, 20% to <30%, 30% to <40%, and ≥40%). A modified multilevel Poisson regression analysis was performed.

Results: In total, 12,611 children were included in the analysis (94.0%). The average school-level proportion of those with no family rules was 32.1% (SD = 9.6). The prevalence of excessive ST was 29.9% (34.9% in boys; 24.8% in girls). The regression analysis showed that excessive ST was significantly associated with both individual-level factors, such as boys (adjusted prevalence ratio (aPR); 1.39), older grades (aPR; 1.18 for 5th grades and 1.28 for 6th grades), late wakeup (aPR; 1.13), physical inactivity (aPR; 1.18 for not so much and 1.31 for rarely), late bedtime (aPR; 1.43 for 10 to 11 p.m. and 1.76 for ≥11 p.m.), frequent irritability (aPR; 1.24 for sometimes and 1.46 for often), feelings of school avoidance (aPR; 1.17 for sometimes and 1.22 for often), infrequent child-parental interaction (aPR; 1.16 for rare and 1.21 for none), no family rules (aPR; 1.56), smartphone ownership (aPR; 1.18), and the school-level proportion of no family rules (aPR; 1.20 for 20% to <30%, 1.29 for 30% to <40%, and 1.43 for ≥40%, setting <20% as reference).

Conclusion: Besides individual factors, a higher school-level proportion of no family rules seemed influential on excessive ST. Increasing the number of households with family rules and addressing individual factors, could be deterrents against excessive ST in children.

Background: Concerns regarding the impact of screen-based sedentary behavior on health have been increasing. Therefore, the present study investigated the longitudinal relationship between multiple screen time and nutrient intake in children and adolescents.

Methods: The present study was conducted utilizing 3 years longitudinal data. Study subjects were 740 Japanese children aged between 6 and 12 years at baseline and between 9 and 15 years in the follow-up. Screen-based sedentary behavior was assessed using screen time, including television (TV) viewing, personal computer (PC) use, and mobile phone (MP) use. The main outcomes were the intakes of nutrients. Mixed effect multivariate linear regression analyses were used to examine the longitudinal relationship between screen-based sedentary time and nutrient intake. Covariates included in the multivariable analysis consisted of sex, age, solitary eating, skipping breakfast, staying up late, and body weight status, as confounders, and physical inactivity, as mediator.

Results: In boys, a longer total screen time longitudinally correlated with higher intake of energy and lower intakes of protein, dietary fiber, minerals, and vitamins. In girls, longer total screen time longitudinally associated with higher intake of sucrose and lower intakes of protein, minerals, and vitamins. In boys, a longer TV viewing time was associated with higher intake of sucrose and lower intakes of protein, minerals, and vitamins. In girls, a longer TV viewing time was associated with higher intake of carbohydrates and lower intakes of protein, fat, minerals, and vitamins. In boys, relationships were observed between a longer PC use time and higher intakes of energy as well as lower intakes of protein, minerals, and vitamins. Relationship was observed between longer PC use time and lower intakes of minerals in girls. An increased MP use time was associated with higher intakes of energy, and lower intakes of protein, sucrose, dietary fiber, minerals, and vitamins in boys. A longer MP use time was associated with higher intakes of fat, and salt as well as lower intakes of carbohydrates, protein, minerals, and vitamins in girls.

Conclusions: The present results revealed that longer screen-based sedentary behaviors were longitudinally associated with nutrient intake in children and adolescents. Future study is needed to elucidate these relationships.

Background: Coronavirus disease 2019 (COVID-19), first reported in December 2019, spread worldwide in a short period, resulting in numerous cases and associated deaths; however, the toll was relatively low in East Asia. A genetic polymorphism unique to East Asians, Aldehyde dehydrogenase 2 rs671, has been reported to confer protection against infections.

Method: We retrospectively investigated the association between the surrogate marker of the rs671 variant, the skin flushing phenomenon after alcohol consumption, and the timing of COVID-19 incidence using a web-based survey tool to test any protective effects of rs671 against COVID-19.

Results: A total of 807 valid responses were received from 362 non-flushers and 445 flushers. During the 42 months, from 12/1/2019 to 5/31/2023, 40.6% of non-flushers and 35.7% of flushers experienced COVID-19. Flushers tended to have a later onset (Spearman’s partial rank correlation test, p = 0.057, adjusted for sex and age). Similarly, 2.5% of non-flushers and 0.5% of flushers were hospitalized because of COVID-19. Survival analysis estimated lower risks of COVID-19 and associated hospitalization among flushers (p = 0.03 and <0.01, respectively; generalized Wilcoxon test). With the Cox proportional hazards model covering 21 months till 8/31/2021, when approximately half of the Japanese population had received two doses of COVID-19 vaccine, the hazard ratio (95% confidence interval) of COVID-19 incidence was estimated to be 0.21 (0.10–0.46) for flusher versus non-flusher, with adjustment for sex, age, steroid use, and area of residence.

Conclusions: Our study suggests an association between the flushing phenomenon after drinking and a decreased risk of COVID-19 morbidity and hospitalization, suggesting that the rs671 variant is a protective factor. This study provides valuable information for infection control and helps understand the unique constitutional diversity of East Asians.

Background: There is limited evidence of a protective effect of Internet use for incident disability (ID) during the COVID-19 pandemic. We investigated the association between frequency of Internet use (FIU) and ID among community-dwelling older people.

Methods: We used longitudinal data from the 2019 and 2022 surveys, including 7,913 residents aged ≥65 without disability at baseline. ID was defined as a new public long-term care insurance certification. FIU at baseline was categorized into daily, weekly, monthly, yearly, and non-users. Changes in FIU before and during the COVID-19 pandemic were categorized into continuing frequent (i.e., daily or weekly), continuing moderate (i.e., monthly or yearly), increase in frequency, from non-users to users, decrease in frequency, from users to non-users, and continuing non-users. Covariates included age, gender, education, perceived economic situation, family structure, body mass index, chronic medical conditions, dietary variety, working status, walking time, and cognitive functioning. Multivariable Poisson regression models were used to estimate adjusted cumulative incidence ratio (aCIR) and 95% confidence interval (CI) for ID.

Results: During the 3-year follow-up, 132 of 4,453 people aged 65–74, 595 of 3,460 people aged ≥75, 287 of 3,660 men, and 440 of 4,253 women developed ID. For FIU at baseline, among people aged ≥75 or men, there was a dose-response relationship between more frequent Internet use at baseline and a lower risk of ID (P-trend was 0.005 in people aged ≥75, and <0.001 in men). Compared to non-users, daily users had a significantly lower risk of ID [aCIR (95% CI) = 0.69 (0.53–0.90) in people aged ≥75, and 0.49 (0.34–0.70) in men]. For changes in FIU, “continuing frequent” and “from non-users to users” had a lower risk of ID than continuing non-users. After stratified analyses, “continuing frequent” remained a significant association in people aged ≥75 or in men, while “from non-users to users” had a significant association in those with daily walking time <30 minutes.

Conclusions: Although FIU may act as a marker of disability, or indicate individual adaptability, our findings suggest that Internet use may be a potential preventive measure against ID in community-dwelling older people when social distancing is required.

Background: Home hot-tub bathing substantially increases drowning mortality rates among older adults in Japan. Previous laboratory studies on hemodynamic responses during hot-tub bathing have been inconsistent depending on the thermal conditions. Furthermore, real-world hemodynamic changes that occur during bathing remain poorly understood. This study investigated the association between individual thermal states and hemodynamic parameters during hot-tub bathing among community-dwelling older adults.

Methods: In this cross-sectional study conducted between January 2016 and April 2019, which involved 1,479 older adults (median [range] age, 68 [40–90] years), skin temperature on the abdominal surface was measured every minute. Ambulatory blood pressure and pulse rate were recorded at 15-min intervals for 24 h. Participants underwent simultaneous living room temperature measurements in their homes, and the time and methods of bathing were recorded. Associations between skin temperature and hemodynamic parameters during bathing and between the pre-bath living room temperature and in-bath maximum proximal skin temperature were evaluated using mixed-effects and linear regression models, respectively.

Results: A 1 °C increase in skin temperature was significantly associated with a 2.41 mmHg (95% confidence interval [CI]: 2.03–2.79) increase in systolic blood pressure and a 2.99 bpm (95% CI: 2.66–3.32) increase in pulse rate, after adjusting for potential confounders, including age, sex, body mass index, antihypertensive medication use, dyslipidemia, diabetes, and living room and outdoor temperatures. Significant interactions were not observed between sex and skin temperature in relation to systolic blood pressure and pulse rate (P = 0.088 and 0.490, respectively). One standard deviation lower living room temperature before bathing was significantly associated with a 0.41 °C (95% CI: 0.35–0.47) higher maximum skin temperature during bathing.

Conclusions: Our findings suggest that pre-bath cold exposure may increase the skin temperature during hot-tub bathing, possibly resulting in excessive hemodynamic changes. This provides a framework for future interventions that utilize pre-bath thermal conditions and bathing environments to prevent bath-related deaths.

Background: Heated tobacco product (HTP) use continues in Japan as the second most common product after cigarettes. While the health effects of HTPs and their secondhand emissions are not well-studied, the tobacco industry has actively marketed HTPs as a smokeless, health-conscious alternative to cigarettes to encourage home consumption. We investigated the prevalence of current tobacco product use and usage at home.

Methods: The present study conducted a cross-sectional analysis of data from the 2023 wave of a nationwide, Internet-based, self-reported survey. 29,354 individuals aged 16–74 were included in the analysis. We assessed the prevalence of current (past-30-day) use for HTPs, cigarettes, non-cigarette combustible tobacco, and dual (combustible plus HTP) use. The frequency of use (daily or more than monthly) in the home was calculated for both HTPs and combustible tobacco. Multivariable Poisson regression models were employed to identify factors associated with home usage. Adjusted prevalence ratios (APRs) and 95% confidence intervals (CIs) were computed. All analyses were weighted to address the Internet-based sample's selectivity and yield nationally representative estimates.

Results: In 2023, the prevalence of current use was 12.4% (HTPs), 18.9% (cigarettes), 3.6% (non-cigarette combustible tobacco), and 7.4% (dual use). Among current users of any tobacco (N = 5,818), 49.8% reported daily tobacco usage within their homes, and 67.1% reported monthly or more frequent home usage. Compared to exclusive combustible tobacco smokers, exclusive HTP users exhibited higher prevalence of daily home usage (APR = 1.54; 95% CI = 1.43–1.67), as did dual users (APR = 1.10; 95% CI = 1.01–1.20). Daily home usage prevalence was notably higher for those without complete tobacco-free rules at home or workplaces, older individuals, and those with lower education levels. Those living with adult or child household member and current drinkers showed significantly lower daily home usage prevalence.

Conclusion: Home usage was more common among HTP users than among combustible tobacco smokers. Ongoing efforts to assess and address the impact of indoor tobacco product use, including HTPs, on health are warranted. Regulatory and educational strategies should be considered to discourage tobacco consumption in both public and private spaces.

Background: Many studies have reported that the Omicron variant is less pathogenic than the Delta variant and the wild-type. Epidemiological evidence regarding the risk of severe COVID-19 from the wild-type to the Omicron variant has been lacking.

Methods: Study participants were COVID-19 patients aged 18 and older without previous COVID-19 infection who were notified to the Nara Prefecture Chuwa Public Health Center from January 2020 to March 2023, during the periods from the wild-type to the Omicron variant. The outcome variable was severe COVID-19 (i.e., ICU admission or COVID-19-related death). The explanatory variable was SARS-CoV-2 variant type or the number of COVID-19 vaccinations. Covariates included gender, age, risk factors for aggravation, and the number of general hospital beds per population. The generalized estimating equations of negative binomial regression models were used to estimate the adjusted incidence proportion (AIP) with 95% confidence interval (CI) for severe COVID-19.

Results: Among 77,044 patients included in the analysis, 14,556 (18.9%) were unvaccinated and 520 (0.7%) developed severe COVID-19. Among unvaccinated patients, the risk of severe COVID-19 increased in the Alpha/Delta variants and decreased in the Omicron variant compared to the wild-type (AIP [95% CI] was 1.55 [1.06–2.27] in Alpha/Delta and 0.25 [0.15–0.40] in Omicron), but differed by age. Especially in patients aged ≥80, there was no significant difference in the risk of severe COVID-19 between the wild-type and the Omicron variant (AIP [95% CI] = 0.59 [0.27–1.29]). Regarding the preventive effect of vaccines, among all study participants, the number of vaccinations was significantly associated with the prevention of severe COVID-19, regardless of variant type. After stratified analyses by age, patients aged ≥80 remained a significant association for all variant types. On the other hand, the number of vaccinations had no association in Omicron BA.5 of patients aged 18–64.

Conclusions: Patients aged ≥80 had less reduction in risk of severe COVID-19 during the Omicron variant period, and a greater preventive effect of vaccines against severe COVID-19, compared to younger people. Our findings suggest that booster vaccination is effective and necessary for older people, especially aged ≥80.

Background: Inadequate sleep behaviors may confer a higher risk of premature death, however, evidence in patients with chronic noncommunicable disease (NCD) is scarce. To investigate the relationship between sleep duration and mortality from all-cause and heart diseases in NCD patients from a prospective cohort.

Methods: Totally, 14,171 participants with at least one NCD, including 8275 with hypertension, 7547 with high cholesterol, 4065 with diabetes, and 5815 with chronic renal failure were enrolled from the National Health and Nutrition Examination Survey during 2005–2014. Cox proportional hazard models were performed to estimate the hazard ratio (HR) for sleep duration and mortality after adjusting for potential confounding factors.

Results: After a median follow-up of 9 years, 2514 all-cause deaths were identified. Compared with sleeping 7–8 h/day, sleeping over 8 h/day was significantly associated with a higher risk of all-cause mortality, where the multivariable-HRs were 1.29 (1.11, 1.50) for hypertension, 1.23 (1.01, 1.51) for high cholesterol, 1.44 (1.13, 1.82) for diabetes, and 1.36 (1.10, 1.68) for chronic renal failure. Similar patterns were observed for heart disease mortality. A nonlinear association was detected between sleep duration and mortality in patients with NCD. Age modified the association in patients with hypertension (P-interaction: 0.036). Trouble sleeping modified the association in patients with diabetes (P-interaction: 0.042).

Conclusions: Long sleep duration was associated with higher risks of all-cause and heart disease mortality in patients with chronic NCD. Our findings highlight that improving sleep behaviors may decrease the risk of premature deaths and help to NCD tertiary prevention.

Background: Owing to shortage of surgical and N95 filtering facepiece respirators (FFRs) during the COVID-2019 pandemic, various masks were developed to prevent infection. This study aimed to examine the inward leakage rate (ILR) of sealed face masks and modified surgical masks using a quantitative fit test and compared it with the ILR of unmodified N95 FFRs.

Methods: We conducted paired comparisons of ILRs of bent nose-fit wire masks, double masks, and N95 FFRs from October to December 2021. To measure the protective effectiveness of masks, participants wore masks, and the number of particles outside and inside the mask were measured. The ILR was based on the percentage of particles entering the mask using a fit tester.

Results: We enrolled 54 participants (20 men and 34 women) in this study. The median ILR for surgical masks without and with a W-shaped bend in the nose-fit wire were 96.44% and 50.82%, respectively. The nose-fit wire adjustment reduced the ILR of surgical masks by a mean of 28.57%, which was significantly lower than the ILR without adjustment (P < 0.001). For double masks, with surgical or polyurethane masks on top of the W-shaped mask, the ILR did not differ significantly from that of N95. Although the filtration performance of double surgical masks matched that of N95 masks, their ILR was notably higher, indicating that double masks do not provide equivalent protection.

Conclusions: Wearing N95 masks alone is effective in many cases. However, surgical mask modifications do not guarantee consistent effectiveness. Properly selected, sealed masks with a good fit overcome leakage, emphasizing their crucial role. Without evidence, mask-wearing may lead to unexpected infections. Education based on quantitative data is crucial for preventing adverse outcomes.

Background: Metabolic Dysfunction-associated Steatotic Liver Disease (MASLD) has become a global epidemic, and air pollution has been identified as a potential risk factor. This study aims to investigate the non-linear relationship between ambient air pollution and MASLD prevalence.

Method: In this cross-sectional study, participants undergoing health checkups were assessed for three-year average air pollution exposure. MASLD diagnosis required hepatic steatosis with at least 1 out of 5 cardiometabolic criteria. A stepwise approach combining data visualization and regression modeling was used to determine the most appropriate link function between each of the six air pollutants and MASLD. A covariate-adjusted six-pollutant model was constructed accordingly.

Results: A total of 131,592 participants were included, with 40.6% met the criteria of MASLD. “Threshold link function,” “interaction link function,” and “restricted cubic spline (RCS) link functions” best-fitted associations between MASLD and PM_2.5, PM₁₀/CO, and O₃ /SO₂/NO₂, respectively. In the six-pollutant model, significant positive associations were observed when pollutant concentrations were over: 34.64 µg/m³ for PM_2.5, 57.93 µg/m³ for PM₁₀, 56 µg/m³ for O₃, below 643.6 µg/m³ for CO, and within 33 and 48 µg/m³ for NO₂. The six-pollutant model using these best-fitted link functions demonstrated superior model fitting compared to exposure-categorized model or linear link function model assuming proportionality of odds.

Conclusion: Non-linear associations were found between air pollutants and MASLD prevalence. PM_2.5, PM₁₀, O₃, CO, and NO₂ exhibited positive associations with MASLD in specific concentration ranges, highlighting the need to consider non-linear relationships in assessing the impact of air pollution on MASLD.

Background and aim: Remnant cholesterol (remnant-C) mediates the progression of major adverse cardiovascular events. It is unclear whether remnant-C, and particularly cumulative exposure to remnant-C, is associated with nonalcoholic fatty liver disease (NAFLD). This study aimed to explore whether remnant-C, not only baseline but cumulative exposure, can be used to independently evaluate the risk of NAFLD.

Methods: This study included 1 cohort totaling 21,958 subjects without NAFLD at baseline who underwent at least 2 repeated health checkups and 1 sub-cohort totaling 2,649 subjects restricted to those individuals with at least 4 examinations and no history of NAFLD until Exam 3. Cumulative remnant-C was calculated as a timeweighted model for each examination multiplied by the time between the 2 examinations divided the whole duration. Cox regression models were performed to estimate the association between baseline and cumulative exposure to remnant-C and incident NAFLD.

Results: After multivariable adjustment, compared with the quintile 1 of baseline remnant-C, individuals with higher quintiles demonstrated significantly higher risks for NAFLD (hazard ratio [HR] 1.48, 95%CI 1.31–1.67 for quintile 2; HR 2.07, 95%CI 1.85–2.33 for quintile 3; HR 2.55, 95%CI 2.27–2.88 for quintile 4). Similarly, high cumulative remnant-C quintiles were significantly associated with higher risks for NAFLD (HR 3.43, 95%CI 1.95–6.05 for quintile 2; HR 4.25, 95%CI 2.44–7.40 for quintile 3; HR 6.29, 95%CI 3.59–10.99 for quintile 4), compared with the quintile 1.

Conclusion: Elevated levels of baseline and cumulative remnant-C were independently associated with incident NAFLD. Monitoring immediate levels and longitudinal trends of remnant-C may need to be emphasized in adults as part of NAFLD prevention strategy.

Background: Menopausal disorders include obscure symptomatology that greatly reduce work productivity among female workers. Quantifying the impact of menopause-related symptoms on work productivity is very difficult because no such guidelines exist to date. We aimed to develop a scale of overall health status for working women in the perimenopausal period.

Methods: In September, 2021, we conducted an Internet web survey which included 3,645 female workers aged 45–56 years in perimenopausal period. We asked the participants to answer 76 items relevant to menopausal symptomatology, that were created for this study and performed exploratory and confirmatory factor analyses for the scale development. Cronbach’s alpha, receiver operating characteristic analysis, and logistic regression analysis were used to verify the developed scale.

Results: Approximately 85% participants did not have menstruation or disrupted cycles. Explanatory factor analysis using the maximum likelihood method and Promax rotation identified 21 items with a four-factor structure: psychological symptoms (8 items, α = 0.96); physiological symptoms (6 items, alpha = 0.87); sleep difficulty (4 items, alpha = 0.92); human relationship (3 items, alpha = 0.92). Confirmatory factor analyses found excellent model fit for the four-factor model (RMSR = 0.079; TLI = 0.929; CFI = 0.938). Criterion and concurrent validity were confirmed with high correlation coefficients between each of the four factors, previously validated menopausal symptom questionnaire, and Copenhagen Burnout Inventory scales, respectively (all ps < 0.0001). The developed scale was able to predict absenteeism with 78% sensitivity, 58% specificity, and an AUC of 0.727 (95%CI: 0.696–0.757). Higher scores of each factor as well as total score of the scale were more likely to be associated with work absence experience due to menopause-related symptoms even after adjusting for Copenhagen Burnout Inventory subscales (all ps < 0.0001).

Conclusion: We found that the developed scale has high validity and reliability and could be a significant indicator of absenteeism for working women in perimenopausal period.

Background: Although social interaction and social support during the “new normal” due to coronavirus disease 2019 (COVID-19) may be related to presenteeism, the effect between these factors has not been clear for Japanese workers. The aim of this study was to describe the presenteeism of Japanese workers with reference to social interaction and social support following the lifestyle changes due to COVID-19 and to assess whether social interaction and social support affected their presenteeism.

Methods: The data were obtained from internet panel surveys from October 2020. Descriptive statistics were calculated, and multiple linear regression was conducted using the data from the first, fourth and fifth surveys, which were conducted during October to November 2020, July to August 2021, and September to October 2021, respectively. To measure presenteeism, questions from “absenteeism and presenteeism questions of the World Health Organization’s Heath and Work Performance Questionnaire”, short version in Japanese was utilized. Multiple linear regressions were conducted to investigate the effects of social interaction and social support-related factors on presenteeism.

Results: A total of 3,407 participants were included in the analysis. The mean score of absolute presenteeism from the fifth survey was 58.07 (SD = 19.71). More time spent talking with family, a larger number of social supporters and a higher satisfaction level for social support were associated with a higher absolute presenteeism score.

Conclusions: Our results suggested that social support reduced the presenteeism of the Japanese workers during the “new normal” due to the COVID-19 pandemic. Social interaction with family also relieved presenteeism.

Background: It is crucial to understand the seasonal variation of Metabolic Syndrome (MetS) for the detection and management of MetS. Previous studies have demonstrated the seasonal variations in MetS prevalence and its markers, but their methods are not robust. To clarify the concrete seasonal variations in the MetS prevalence and its markers, we utilized a powerful method called Seasonal Trend Decomposition Procedure based on LOESS (STL) and a big dataset of health checkups.

Methods: A total of 1,819,214 records of health checkups (759,839 records for men and 1,059,375 records for women) between April 2012 and December 2017 were included in this study. We examined the seasonal variations in the MetS prevalence and its markers using 5 years and 9 months health checkup data and STL analysis. MetS markers consisted of waist circumference (WC), systolic blood pressure (SBP), diastolic blood pressure (DBP), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), fasting plasma glucose (FPG).

Results: We found that the MetS prevalence was high in winter and somewhat high in August. Among men, MetS prevalence was 2.64 ± 0.42 (mean ± SD) % higher in the highest month (January) than in the lowest month (June). Among women, MetS prevalence was 0.53 ± 0.24% higher in the highest month (January) than in the lowest month (June). Additionally, SBP, DBP, and HDL-C exhibited simple variations, being higher in winter and lower in summer, while WC, TG, and FPG displayed more complex variations.

Conclusions: This finding, complex seasonal variations of MetS prevalence, WC, TG, and FPG, could not be derived from previous studies using just the mean values in spring, summer, autumn and winter or the cosinor analysis. More attention should be paid to factors affecting seasonal variations of central obesity, dyslipidemia and insulin resistance.

Background: There are few multi-city studies on the association between temperature and mortality in basin climates. This study was based on the Sichuan Basin in southwest China to assess the association of basin temperature with non-accidental mortality in the population and with the temperature-related mortality burden.

Methods: Daily mortality data, meteorological and air pollution data were collected for four cities in the Sichuan Basin of southwest China. We used a two-stage time-series analysis to quantify the association between temperature and non-accidental mortality in each city, and a multivariate meta-analysis was performed to obtain the overall cumulative risk. The attributable fractions (AFs) were calculated to access the mortality burden attributable to non-optimal temperature. Additionally, we performed a stratified analyses by gender, age group, education level, and marital status.

Results: A total of 751,930 non-accidental deaths were collected in our study. Overall, 10.16% of non-accidental deaths could be attributed to non-optimal temperatures. A majority of temperature-related non-accidental deaths were caused by low temperature, accounting for 9.10% (95% eCI: 5.50%, 12.19%), and heat effects accounted for only 1.06% (95% eCI: 0.76%, 1.33%). The mortality burden attributable to non-optimal temperatures was higher among those under 65 years old, females, those with a low education level, and those with an alternative marriage status.

Conclusions: Our study suggested that a significant association between non-optimal temperature and non-accidental mortality. Those under 65 years old, females, and those with a low educational level or alternative marriage status had the highest attributable burden.