BACKGROUND: High temperatures are known to be associated with an increased risk of self-harm, but the influence of demographic changes and country-level indicators on the burden of heat-related self-harm remains unclear. This study examined the key factors driving changes in self-harm mortality linked to high temperatures and explored their impact at the country level. METHODS: This is an ecological study that analyzes data from the 2021 Global Burden of Disease (GBD) study, the World Bank, and the Climate Research Unit (CRU) were analyzed. Decomposition analyses were used to identify key factors driving changes in high temperature-related self-harm mortality between 1990 and 2021. A panel data model assessed the impact of national indicators on heat-related self-harm mortality. RESULTS: In 2021, 14,885 deaths globally were attributed to heat-related self-harm, a 41.94% increase from 1990, with low-middle SDI regions accounting for 47.84% of these deaths. While the global death rate from heat-related self-harm declined slightly over this period, South Asia and low-middle SDI regions contributed most to the decline. However, population aging exacerbated mortality rates. Demographic and meteorological factors were also linked to heat-related self-harm. CONCLUSION The global decline in heat-related self-harm mortality is largely driven by reductions in females, low-middle SDI regions, and South Asia. However, population aging and growth in these regions have added to the mortality burden, slowing the overall decline. Factors such as population density are also associated with heat-related self-harm. Targeted measures are needed to mitigate heat-induced self-harm more effectively in future.
Humans ; Self-Injurious Behavior/etiology* ; Hot Temperature/adverse effects* ; Global Health/statistics & numerical data* ; Female ; Male ; Adult ; Middle Aged ; Aged ; Young Adult ; Adolescent

BACKGROUND: Older adults in Japan have the highest drowning mortality rate globally due to frequent bathing practices. Low outdoor temperatures have been linked to bath-related deaths; however, previous studies employed limited statistical models and focused on a single prefecture. Given Japan's aging population, preventing bath-related deaths is a public health priority. This study aimed to analyze the association between outdoor temperature and bath-related drowning deaths across Japan from 1995 to 2020 (n = 110,938), examining regional variations and identifying contributing prefectural characteristics. METHODS: Daily counts of bath-related drowning deaths per prefecture were matched with daily mean temperature data from the Japan Meteorological Agency. Prefecture-level demographic and environmental data were obtained from Japan's Official Statistics. We applied a generalized additive mixed model to examine the association between daily mean temperature and bath-related drowning death risk. Meta-regression was used to identify prefecture-level modifiers. RESULTS: Bath-related drowning death risk peaked at a daily mean temperature of 1.8 °C (relative risk [RR] 9.7, 95% confidence interval [CI]: 9.5-9.9), compared with the lowest risk at 30.3 °C. The association was stronger at mid-range temperatures, particularly among males and individuals aged ≥65 years. Among prefectures, Kagoshima-the southernmost prefecture on Japan's main islands-had the highest maximum RR at 19.6 (95% CI: 16.2-23.6), while Hokkaido-the northernmost prefecture-had the lowest at 3.8 (95% CI: 3.4-4.3). Prefecture-level factors that strengthened this relationship included a lower prevalence of double-pane windows as a proxy of housing insulation and higher annual mean temperatures with ratio of RR change per one standard deviation increase of 0.76 (95% CI: 0.69-0.83) and 1.27 (95% CI: 1.18-1.37), respectively. CONCLUSIONS Warmer prefectures in southern regions exhibited greater maximum-to-minimum risk ratios compared to cooler northern prefectures. This paradoxical finding underscores the importance of region-specific interventions to reduce bath-related deaths.
Japan/epidemiology* ; Humans ; Drowning/epidemiology* ; Male ; Aged ; Female ; Baths/statistics & numerical data* ; Middle Aged ; Temperature ; Aged, 80 and over ; Adult ; Young Adult ; Risk Factors ; Adolescent

BACKGROUND: Neck cooling is a practical method for preventing heat-related illness, however, its effectiveness in general workers is not well established. This study aimed to assess the effects of neck cooling on core body temperature and other physiological markers during exercise in a hot environment. METHODS: This randomized crossover trial was conducted from November 2023 to April 2024 at the Shared-Use Research Center at UOEH. Fourteen healthy adult males participated in the study under two conditions: with neck cooling (COOL) and without neck cooling (CON). All participants completed both conditions, and the order of condition assignment was determined by a random draw. Participants first rested for 10 minutes in a 28.0 °C, 50% relative humidity environment, followed by a rest in a 35.0 °C, 50% relative humidity environment for another 10 minutes. In the COOL condition, participants wore a neck cooler containing 1,200 g of ice while exercising at 50% Heart Rate Reserve on a bicycle ergometer for 20 minutes. Afterward, they rested for 15 minutes in the hot environment while still wearing the cooler. MAIN OUTCOME MEASURES: Core body temperature (rectal and esophageal), forehead skin temperature, and heart rate were continuously monitored and compared using a mixed model. Estimated sweat volume was calculated based on changes in body weight before and after the experiment. RESULTS: At the end of the rest period, no significant differences were observed between the COOL and CON conditions in rectal temperature (37.76 ± 0.18 °C versus 37.75 ± 0.24 °C, p = 0.9493), esophageal temperature (37.75 ± 0.30 °C versus 37.76 ± 0.23 °C, p = 0.7325), forehead skin temperature (36.87 ± 0.29 °C versus 36.88 ± 0.27 °C, p = 0.2160), or heart rate (104.18 ± 7.56 bpm versus 107.52 ± 7.40 bpm, p = 0.1035). Estimated sweat loss was similar between conditions (578 ± 175 g for CON versus 572 ± 242 g for COOL, p = 0.5066). While more participants felt cooler in the COOL condition, RPE showed no significant difference. CONCLUSION Neck cooling did not significantly affect core temperature or perceived exertion. Maintaining close contact with the skin at sufficiently low temperatures or utilizing cooling methods that prevent excessive negative feedback may be necessary to enhance the effectiveness of neck cooling.
Humans ; Male ; Cross-Over Studies ; Exercise/physiology* ; Adult ; Neck/physiology* ; Hot Temperature/adverse effects* ; Young Adult ; Body Temperature ; Heart Rate ; Skin Temperature ; Body Temperature Regulation ; Cold Temperature

BACKGROUND: Although smoking rates have been declining worldwide, new types of tobacco products have been gradually spreading in recent years, especially in Japan, where heated tobacco products (HTPs) users are rapidly increasing. Oxidative stress caused by reactive oxygen species (ROS) is one of the causes of smoking-induced carcinogenesis, respiratory diseases, and cardiovascular diseases. However, information on the amount of ROS contained in mainstream smoke from HTPs is limited. In this study, we measured the amount of ROS generated from HTPs to evaluate the oxidative stress-related toxicity of HTPs. METHODS: IQOS ILUMA, glo hyper+, and Ploom X ADVANCED were used as the HTP devices. Mainstream smoke was collected from each HTP according to Health Canada Intense regime (smoke volume, 55 mL; smoke duration, 2 s). The collected ROS were reacted with 2,7'-dichlorodihydrofluorescein reagents, and the amount of ROS was calculated as H₂O₂ equivalent from the fluorescence intensity obtained. RESULTS: The ROS in the mainstream smoke from IQOS ILUMA, glo hyper+ (high-temperature mode), and Ploom X ADVANCED was found to be 48.8 ± 8.6, 86.6 ± 12.6, and 40.8 ± 5.7 nmol H₂O₂/stick, respectively (n = 6, mean ± standard deviation), with the highest being from glo hyper+ (high-temperature mode). The amount of ROS was significantly higher in the high-temperature mode of glo hyper+ than in the standard mode of glo hyper+. Additionally, the estimated amount of ROS from smoking 20 heated sticks per day (674-2160 nmol H₂O₂/day) was equivalent to 2.2-96 times the amount of daily exposure to ROS in the urban atmosphere (approximately 22-300 nmol H₂O₂/day). CONCLUSIONS We found that ROS is generated from HTPs of different devices. This study suggests that HTPs users may be exposed to much more ROS than they are exposed to in normal life.
Reactive Oxygen Species/analysis* ; Tobacco Products/analysis* ; Smoke/analysis* ; Hot Temperature ; Japan ; Oxidative Stress

BACKGROUND: Previous studies have shown that old age and cold temperatures are risk factors for bathing-related accidents (BRAs) in Japan. The differences between outdoor and indoor temperatures are believed to depend on the housing type (detached houses or apartment buildings). This study aimed to investigate the associations between age, temperature, and BRAs according to housing type in Japan. METHODS: We included cases in which patients were transported by ambulance from domestic bathrooms between April 2016 and March 2022 in Nagoya city. Age-specific BRA incidence rates measured by 5-year age groups, temperature-specific age-adjusted standardized incidence rates (SIRs) for BRA calculated by temperature quintile groups, and the BRA risk regarding temperature based on a time-stratified case-crossover (CCO) design were compared between detached houses and apartment buildings. RESULTS: We observed 4,848 ambulance dispatches owing to BRAs (3,083 in detached houses and 1,765 in apartment buildings; SIR for detached houses compared to apartment buildings: 1.37; 95% confidence interval [CI]: 1.33-1.43). The ratio of detached houses to apartment buildings in the age-specific BRA incidence was almost the same in middle-aged people, but it significantly increased from the age of 70 years onward (incidence rate ratio for the 70-74-years age group: 1.74; 95% CI: 1.43-2.11). Temperature-specific SIR for detached houses compared to apartment buildings was not significantly different in the hottest temperature quintile but increased significantly in the other colder temperature quintiles (SIR in coldest quintile: 1.56; 95% CI: 1.47-1.66). BRA risk based on CCO design increased significantly with a decrease in temperature in detached houses (risk ratio [RR] for 3 °C: 1.25; 95% CI: 1.05-1.47), but not in apartment buildings (RR for 3 °C: 1.07; 95% CI: 0.86-1.34). CONCLUSIONS Detached houses had higher BRA incidence rates than apartments. Older age and lower temperatures, which are risk factors for BRAs, were more prevalent in detached houses than in apartment buildings. Thus, public health measures that focus on detached houses are necessary for preventing BRAs in Japan.
Humans ; Japan/epidemiology* ; Aged ; Middle Aged ; Housing/statistics & numerical data* ; Baths/adverse effects* ; Ambulances/statistics & numerical data* ; Male ; Adult ; Female ; Temperature ; Incidence ; Aged, 80 and over ; Young Adult ; Age Factors ; Adolescent ; Child, Preschool ; Infant ; Child ; Risk Factors ; Infant, Newborn ; Accidents, Home/statistics & numerical data*

BACKGROUND: Heated tobacco products (HTPs) are widely used in Japan, following cigarettes, but their health effects remain unclear. HTPs are often considered a less harmful alternative to cigarettes and are commonly used by adults with asthma, even though smoking is one of the most obvious and treatable factors in asthma. We aimed to elucidate the association between HTP use and asthma symptoms in adults with asthma. METHODS: A total of 3,787 individuals with asthma were extracted from the data in the Japan COVID-19 and Society Internet Survey 2023, an ongoing longitudinal internet-based cohort study conducted by a nationwide internet research company in Japan. They were categorized into three groups (never, past, and current smokers) based on cigarette use. The association between HTP use and worsening of asthma symptoms within the previous 2 months in each group was analyzed using univariate and multivariate logistic regression analyses. Both exposure and outcomes were assessed by self-reporting. RESULTS: Among the participants, 2,470 (65.2%) were never smokers, 845 (22.3%) were past smokers, and 472 (12.5%) were current smokers. Overall, the proportion of HTP users was 429 (11.3%), and worsened asthma symptoms were observed in 400 (10.6%) individuals. The total proportion of HTP users and worsened asthma symptoms was 70 (2.8%) and 259 (10.5%) among never smokers, 180 (21.3%) and 72 (8.5%) among past smokers, and 179 (37.9%) and 69 (14.6%) among current smokers. After adjusting for confounders, the odds ratio (OR) was 3.25 (95% confidence interval [CI] 1.86-5.68, p < 0.001), 1.47 (95% CI 0.93-2.34, p = 0.1), and 2.23 (95% CI 1.46-3.43, p < 0.001) for never, past, and current cigarette smokers with HTP use, respectively, where never smokers without HTP use were set as the standard. CONCLUSION The use of HTPs, not only cigarette smoking, was associated with worsening of asthma symptoms in adults with asthma. Therefore, people need to understand the harmful effects of HTPs on asthma symptoms.
Humans ; Japan/epidemiology* ; Asthma/etiology* ; Male ; Female ; Middle Aged ; Adult ; Aged ; Tobacco Products/adverse effects* ; Internet ; Surveys and Questionnaires ; Young Adult ; Hot Temperature ; Longitudinal Studies

BACKGROUND: Prior studies have shown that drivers with type 2 diabetes are more likely to be involved in motor vehicle collisions (MVCs) compared to the general population. Certain meteorological factors have been increasingly recognized as contributors to MVC risk. This study aims to examine the association of MVCs with temperature, rainfall, wind speed, and sunshine duration among drivers with type 2 diabetes. METHODS: Using Taiwan's National Health Insurance data (2019-2021), we identified individuals diagnosed with type 2 diabetes and linked their records to the Police-Reported Traffic Accident Registry to obtain daily MVC counts. Meteorological data were sourced from the Central Weather Administration. Associations between daily weather conditions and MVCs were assessed using a Distributed Lag Non-Linear Model. RESULTS: Over the 1,096-day study period, 170,468 MVC events involving drivers with type 2 diabetes were recorded. A U-shaped association was observed between same-day temperature and MVC rates. Compared with the reference temperature of 17.5 °C, both lower temperatures (≤15 °C; rate ratio [RR] = 1.014-1.053) and higher temperatures (≥30 °C; RR = 1.062) were associated with increased MVC risk. Rainfall showed an inverse relationship with MVCs. Compared with 70 mm of rainfall, the lowest MVC rate occurred at 129 mm (RR = 0.873), while the highest was on rain-free days (0 mm; RR = 1.068). Stronger effects were observed when lag periods up to 14 days were considered. Wind speed and sunshine duration were not significantly associated with MVC risk. CONCLUSIONS These findings suggest that drivers with type 2 diabetes should exercise greater caution on days with extreme temperatures or in days with lesser rainfall, as these conditions may elevate MVC risk.
Humans ; Diabetes Mellitus, Type 2/epidemiology* ; Taiwan/epidemiology* ; Accidents, Traffic/statistics & numerical data* ; Male ; Middle Aged ; Female ; Weather ; Aged ; Adult ; Temperature ; Risk Factors

BACKGROUND: Globally, Japan has the highest drowning mortality among older adults, largely because of bathing customs. Although this mortality rate peaks in winter, the nationwide impact of outdoor temperature has not been quantified, and whether specific days carry greater risks for bathtub drowning deaths remains unclear. Therefore, we aimed to address these gaps using nationwide data from Japan. METHODS: We collected daily data on outdoor temperatures and bathtub drowning deaths (from death certificates), along with population data, across 47 prefectures from 1995-2020. A time series regression model incorporating a cyclic spline for day-of-year and a cross-basis function for outdoor temperature was used to estimate seasonality and temperature attributable fractions (AFs). Prefecture-specific estimates were pooled using meta-analysis. National holidays were defined by the Act on National Holidays. RESULTS: During the study period, 99,930 home bathtub drowning deaths were recorded. The AF for seasonality modelled with a cyclic spline for day-of-year was 77.8% (empirical confidence interval [eCI]: 76.7-78.8%), which decreased to 15.3% (eCI: 13.1-18.0%) after adjusting for outdoor temperature, indicating that outdoor temperature accounted for 80.3% of the seasonal effect. Elevated risks were observed on Sundays (relative risk = 1.16, 95% CI: 1.12-1.20), holidays (1.12, 95% CI: 1.08-1.16), New Year's Day (1.72, 95% CI: 1.61-1.84), and New Year's Eve (1.63, 95% CI: 1.52-1.74) in the adjusted model, which included a cyclic spline for day-of-year and a cross-basis function for outdoor temperature. CONCLUSION Our findings highlight the importance of mitigating the impact of outdoor temperature on bath-related death risk. Identifying high-risk days can be used to help develop targeted preventive strategies.
Seasons ; Humans ; Drowning/epidemiology* ; Japan/epidemiology* ; Temperature ; Aged ; Male ; Adult ; Female ; Middle Aged ; Child ; Young Adult ; Adolescent ; Aged, 80 and over ; Child, Preschool

OBJECTIVE: To compare the cyclic fatigue resistance of nickel-titanium files made by 3 new heat treatment in simulated S-shaped root canals at different temperatures. METHODS: Gold heat-treated nickel-titanium files TruNatomy (25 mm, tip size 26#/0.04) and ProTaper Gold (25 mm, tip size 25#/0.08) were selected as the experimental group, M wire technique nickel-titanium file ProTaper Next (25 mm, tip size 25#/0.06) was selected as the control group. It was speculated that the Gold technique used in TruNatomy nickel-titanium file was R phase separation technique, which included a complete intermediate R-phase, increasing its flexibility. ProTaper Gold was a CM wire nickel-titanium file and the increased phase transformation temperature by heat treatment introduced martensite at room temperature, while it underwent gold heat treatment on the surface, generating an intermediate R phase during phase transformation, providing hyperelastic. ProTaper Next used M wire technique, M wire included austenite at room temperature, where heat mechanical processing introduced hardened martensite, which was incapable of participating phase transformation. Because of the lower elastic modulus of hardened martensite than austenite, the flexibility of the file was increased. Twenty instruments of each nickel-titanium file were submitted to the cyclic fatigue test by using a simulated canal with double curvatures at room tem-perature (24 ℃) and 65 ℃, 10 instruments of each nickel-titanium file were selected at each temperature (n=10). At the same temperature, the number of cyclic fatigue (NCF) and fragment length were analyzed by using One-Way analysis of variance at a significance level of P < 0.05. NCF and fragment length of the same nickel-titanium file at room temperature and 65 ℃ were compared by paired sample t test and the significance level was α=0.05. Fractured surfaces were analyzed by using scanning electron microscope. RESULTS: In double-curved canals, all the failure of the files due to cyclic fatigue was first seen in the apical curvature before the coronal curvature. At room temperature, in the apical curvature, NCF of TruNatomy was 344.4±96.6, ProTaper Gold was 175.0±56.1, ProTaper Next was 133.3±39.7, NCF of Tru Natomy was the highest (P < 0.05). In the coronal curvature, NCF of TruNatomy was 618.3± 75.3, ProTaper Gold was 327.5±111.8, ProTaper Next was 376.6±67.9, NCF of TruNatomy was also the highest (P < 0.05). There was no significant difference among the apical and coronal fragment length of the 3 nickel-titanium files (P>0.05). At 65 ℃, in the apical curvature, NCF of TruNatomy was 289.6±65.8, ProTaper Gold was 187.5±75.4, ProTaper Next was 103.0±38.5, NCF of TruNatomy was the highest (P < 0.05). In the coronal curvature, NCF of TruNatomy was 454.2±45.4, ProTaper Gold was 268.3±31.4, ProTaper Next was 283.8±31.7, NCF of TruNatomy was also the highest (P < 0.05). The apical fragment length of ProTaper Next was the highest (P < 0.05), and there was no significant difference among coronal fragment length of the 3 nickel-titanium files (P>0.05). Compared with room temperature, at 65 ℃, in the coronal curvature, NCF of TruNatomy decreased significantly (P < 0.05). The fractured surfaces of the three nickel-titanium files demonstrated typical cyclic fatigue. CONCLUSION Gold heat-treated nickel-titanium file had better cyclic fatigue resistance than M wire nickel-titanium file in S-shaped root canals.
Nickel/chemistry* ; Titanium/chemistry* ; Hot Temperature ; Root Canal Preparation/methods* ; Humans ; Materials Testing ; Gold/chemistry* ; Dental Alloys/chemistry* ; Stress, Mechanical

OBJECTIVE: To observe the skin surface temperature at the related back-shu points in the patients with the different levels of pulmonary ventilation function in chronic persistent asthma, and to explore the correlation between the skin temperature at the back-shu points and pulmonary ventilation function indexes based on "lung governing the skin and hair". METHODS: Sixty-one patients with chronic persistent asthma, based on the level of pulmonary ventilation function, were assigned into a reduced pulmonary ventilation function group (reduced function group, 32 cases) and a normal pulmonary ventilation function group (normal function group, 29 cases). In the two groups, the skin surface temperature was measured in the sites of bilateral Feishu (BL13), Geshu (BL17), Pishu (BL20) and Shenshu (BL23); and the pulmonary ventilation function indexes (the percentage of predicted value of forced vital capacity [FVC%pred], the percentage of predicted value of forced expiratory volume in the first second [FEV1%pred], the percentage of predicted value of FEV1/FVC [FEV1/FVC%pred] and the percentage of predicted value of the peak expiratory flow [PEF%pred]) were recorded. The correlation between the skin surface temperature of acupoints and pulmonary ventilation function was analyzed. RESULTS: Compared with the normal function group, the surface skin temperature at the bilateral Feishu (BL13), Geshu (BL17), Pishu (BL20) and Shenshu (BL23) was higher in the reduced function group (P<0.05, P<0.01). Compared with the normal function group, FEV1%pred, FEV1/FVC%pred and PEF%pred were decreased in the reduced function group (P<0.001). There was no significant difference in FVC%pred between the two groups (P>0.05). The skin surface temperature at the bilateral Feishu (BL13), Geshu (BL17), Pishu (BL20) and Shenshu (BL23) was negatively correlated with FVC%pred, FEV1%pred, FEV1/FVC%pred and PEF%pred in 61 patients with chronic persistent asthma (P<0.001, P<0.01, P<0.05). CONCLUSION The skin surface temperature at back-shu points is elevated in line with the the decline of pulmonary ventilation function in the patients with chronic persistent asthma, presenting a negative correlation with pulmonary ventilation function indexes. It is preliminarily verified that back-shu point is characterized by reflecting the visceral disorders.
Humans ; Female ; Male ; Asthma/therapy* ; Middle Aged ; Adult ; Skin Temperature ; Lung/physiopathology* ; Acupuncture Points ; Pulmonary Ventilation ; Aged ; Chronic Disease/therapy* ; Young Adult ; Hair