Short-term effects of air temperature on blood pressure and pulse pressure in potentially susceptible individuals

Susceptibility of hypertensive individuals to acute blood pressure increases in response to personal-level environmental temperature decrease

BACKGROUND

Environmental temperature is negatively associated with blood pressure (BP), and hypertension may exacerbate this association. The aim of this study is to investigate whether hypertensive individuals are more susceptible to acute BP increases following temperature decrease than non-hypertensive individuals.

METHODS

The study panel consisted of 126 hypertensive and 125 non-hypertensive (n = 251) elderly participants who completed 940 clinical visits during the winter of 2016 and summer of 2017 in Beijing, China. Personal-level environmental temperature (PET) was continuously monitored for each participant with a portable sensor platform. We associated systolic BP (SBP) and diastolic BP (DBP) with the average PET over 24 h before clinical visits using linear mixed-effects models and explored hourly lag patterns for the associations using distributed lag models.

RESULTS

We found that per 1 °C decrease in PET, hypertensive individuals showed an average (95 % confidence interval) increase of 0.96 (0.72, 1.19) and 0.28 (0.13, 0.42) mmHg for SBP and DBP, respectively; and non-hypertensive participants showed significantly smaller increases of 0.28 (0.03, 0.53) mmHg SBP and 0.14 (-0.01, 0.30) mmHg DBP. A lag pattern analysis showed that for hypertensive individuals, the increases in SBP and DBP were greatest following lag 1 h PET decrease and gradually attenuated up to lag 10 h exposure. No significant BP change was observed in non-hypertensive individuals associated with lag 1-24 h PET exposure. The enhanced increase in PET-associated BP in hypertensive participants (i.e., susceptibility) was more significant in winter than in summer.

CONCLUSIONS

We found that a decrease in environmental temperature was associated with acute BP increases and these associations diminished over time, disappearing after approximately 10 hours. This implies that any intervention measures to prevent BP increases due to temperature drop should be implemented as soon as possible. Such timely interventions are particularly needed for hypertensive individuals especially during the cold season due to their increased susceptibility.

Short-term effects of heatwaves on clinical and subclinical cardiovascular indicators in Chinese adults: A distributed lag analysis

AIMS

Previous studies have related heat waves to morbidity and mortality of cardiovascular diseases; however, potential mechanisms remained limited. Our aims were to investigate the short-term effects of heat waves on a series of clinical/subclinical indicators associated with cardiovascular health.

METHODS

Our study used 80,574 health examination records from the Health Management Center of Nanjing Zhongda Hospital during the warm seasons of 2019-2021, including 62,128 participants. A total of 11 recognized indicators of cardiovascular risk or injury were assessed. Air pollution and meteorological data were obtained from the Nanjing Ecological Environment Bureau and the China Meteorological Data Network, respectively. Heat waves were defined as a daily average temperature over the 95th percentile for three or more consecutive days from May to September. We used a combination of linear mixed effects models and distributed lag nonlinear models to assess the lagged effects of heat waves on clinical and subclinical cardiovascular indicators. Stratified analyses based on individuals' characteristics, including gender, age, body mass index (BMI), diabetes, and hypertension, were also performed.

RESULTS

Heat waves were related to significant changes in most indicators, with the magnitude of effects generally peaking at a lag of 0 to 3 days. Moreover, the cumulative percentage changes over lag 0-7 days were -0.82 % to -2.55 % in blood pressure, 1.32 % in heart rate, 0.20 % to 2.66 % in systemic inflammation markers, 0.36 % in a blood viscosity parameter, 9.36 % in homocysteine, and 1.35 % to 3.25 % in injuring myocardial enzymes. Interestingly, females and males showed distinct susceptibilities in different indicators. Stronger effects were also found in participants aged 50 years or over, individuals with abnormal BMI status, and patients with diabetes.

CONCLUSION

Short-term exposure to heat waves could significantly alter clinical/subclinical cardiovascular indicator profiles, including blood pressure changes, increased heart rate, acute systemic inflammation, elevated blood viscosity, and myocardial injury.

The impact of daily mean air temperature on the proportion of time in hypoglycemia in 2,582 children and adolescents with type 1 diabetes - Is this association clinically relevant?

OBJECTIVES

To study the potential association between increases in daily mean air temperature and time below range (TBR <54 mg/dl) and time above range (TAR >250 mg/dl) in children and adolescents with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Individuals with type 1 diabetes <21 years with information on daily glucose profiles from the diabetes prospective follow-up study (DPV) were included (n = 2582). Further inclusion criteria were age at least 6 months at diabetes onset, diabetes duration for at least one year and treatment years 2020-2021. Mean daily air temperature and other meteorological parameters from 78 measurement stations in Germany were linked to the individual glucose sensor profile via the five-digit postcode areas of residency. We used multivariable repeated measures fractional logistic regression models with a compound symmetry covariance structure to study the association between a 1 °C increase in daily mean temperature and time in specific glucose ranges.

RESULTS

A 1 °C increase in daily mean temperature was associated with an acute (Odds Ratio (OR) 1.009 (95%-CI 1.007, 1.011)) and up to 7 days delayed (OR 1.003 (1.001, 1.005)) increase in TBR <54 mg/dl. Moreover, an acute decrease in TAR >250 mg/dl (OR 0.997 (0.996, 0.997)) was found.

CONCLUSIONS

Results of the DPV registry showed small, but statistically significant changes in TBR and TAR in association with a short-term temperature increase. Higher blood flow and faster insulin absorption might be one possible mechanism. In times of increasing temperature fluctuations meteorological impacts on time in range could become even more relevant.

Ambient temperature and ambulatory blood pressure: An hourly-level, longitudinal panel study

BACKGROUND

Variations of blood pressure (BP) related to air temperature have been reported previously; however, no evidence is available regarding the association of hourly ambient temperature with ambulatory blood pressure.

METHODS

We conducted a longitudinal panel study among 1895 patients from an outpatient department who received repeated ambulatory blood pressure monitoring in Urumqi, China between July 2020 and December 2021. We obtained hourly ambient temperature from the nearest monitoring station to the residential address, and measured 4 ambulatory blood pressure indicators. Linear mixed-effect model combined with distributed lag models were applied to investigate the cumulative associations of hourly temperature with BP.

RESULTS

A total of 97,466 valid blood pressure measurements were evaluated. We observed almost linear and monotonically decreasing relationships between temperature and blood pressure. The effects occurred in the same hour, attenuated thereafter and became insignificant approximately 36 h. A 10 °C decrease in temperature was significantly associated with increments of 0.84 mmHg in systolic blood pressure, 0.56 mmHg in diastolic blood pressure, 1.38 mmHg in mean arterial pressure, and 0.66 mmHg in pulse pressure over lag 0 to 36 h. Stronger associations were found among patients of female sex, age between 18 and 65 years, overweight or obesity, minority, less education or in the cold season, as well as those without hypertension or with coronary heart disease, or did not take anti-hypertension medication.

CONCLUSION

Our study provides robust evidence that hourly ambient temperature is inversely associated with ambulatory blood pressure. It also highlights a linear relationship between decreased ambient temperature and elevated BP, which may have implications for the prevention and management of hypertension in susceptible populations.

Cumulative effects of temperature on blood pressure during pregnancy: A cohort study of differing effects in three trimesters

BACKGROUND

Little is known about the non-linear cumulative effects of temperature on blood pressure (BP) during pregnancy. We investigated the differing effects of daily ambient temperature on BP for up to 30 days in three trimesters.

METHODS

The first, second, and third trimester analyses included 2547, 2299, and 2011 pregnant women, respectively, from a prospective cohort in Nanjing from January 2017 to January 2020. BP was measured at each follow-up visit. The individual daily temperature exposures were calculated for 30 days prior to the follow-up date. The Distributed Lag Non-linear Model was used to investigate the relationship between temperature and BP in each trimester.

RESULTS

Temperatures under 15 °C elevate systolic, diastolic BP, and mean arterial pressure (SBP, DBP, and MAP) in the first trimester, while temperatures above 15 °C reduce SBP in the second and third trimesters. By using Distributed Lag Linear Models, we estimated that with a 1 °C decrease in daily temperature, the SBP and DBP increased by 0.32 (95 % CI: 0.12, 0.52) and 0.23 (95 % CI: 0.07, 0.39) mmHg, respectively, in the first trimester with a 20-day cumulative lag, while with a 1 °C increase in daily temperature, the SBP decreased by 0.23 (0.35, 0.10) mmHg in the third trimester with a 30-day cumulative lag. The significant effects of temperature mainly manifested between 2 and 4 weeks of exposure.

CONCLUSIONS

Temperature has different effects on BP over three trimesters. Protective measures to reduce cold-related BP rise will help reduce the risk of hypertensive disorders of pregnancy.

Cardiovascular mortality risks during the 2017 exceptional heatwaves in China

Climate change has made disastrous heatwaves more frequent. Heatwave-related health impacts are much more devastating for more intense heatwaves. In the summer of 2017, exceptional heatwaves occurred in many regions, including China. This study aims to evaluate the cardiovascular mortality risk associated with the 2017 exceptional heatwaves and compare the mortality risk of the severe heatwaves with those in other years. Using daily data for a spectrum of cardiovascular mortality and temperature for 102 Chinese counties (2014-2017), we estimated the association between heatwave and mortality by generalized linear mixed-effects models. Compared with matched non-heatwave days, mortality risks on heatwaves days in 2017 increased 27.8% (95% CI, 14.8-42.3%), 26.7% (8.0-48.5%), 30.1% (10.2-53.7%), 27.3% (1.4-59.9%), 32.2% (3.4-68.4%), and 25.2% (1.0-57.7%) for total circulatory diseases, cerebrovascular disease, ischemic heart disease (IHD), acute IHD, chronic IHD, and myocardial infarction. The 2017 exceptional heatwaves impacted ischemic heart disease mortality and myocardial infarction mortality more than heatwaves in 2014-2016. Here we show that the severe heatwaves in 2017 posed catastrophic death threats for those under-studied cardiovascular diseases.

Does the economic growth target overweight induce more polluting activities? Evidence from China

In China, official promotion evaluation based on economic performance motivates local governments to develop high economic growth targets, which has played an active role in boosting China's economic growth in the past decades, whereas its environmental consequences have not been fully exploited. This paper finds that the economic growth target overweight has a stronger positive impact on the output of high-polluting industries than on the output of low-polluting industries, thus inducing more polluting activities. To deal with the issues of reverse causality and omitted variables bias, we take an instrumental variable approach. Examining mechanisms, we show that economic growth target overweight promotes polluting activities through the deregulation of the polluting activities in high-polluting industries. We also find an increase in the impact of the economic growth target overweight after the 2008 global economic crisis. Our study provides new evidence for explaining the dual presence of rapid economic growth and heavy environmental pollution in China.

Ambient Temperature and Cardiac Biomarkers: A Meta-Analysis

This study quantified the effect of cold or heat exposure of ambient temperature on the alteration of well-known cardiac markers. A meta-analysis was performed using the PRISMA guidelines. Peer-reviewed studies on ambient temperature and cardiac biomarkers were retrieved from MEDLINE, ScienceDirect and Google Scholar from January 2000 to February 2022. The pooled effect sizes of ambient temperature on cardiac biomarkers c-reactive protein, soluble-cell adhesion-molecule-1, soluble-intercellular-adhesion-molecule-1, total cholesterol, low-densitylipoprotein, interleukin-6, B-type-Natriuretic-Peptide; systolic/diastolic blood pressure were quantified using a random-effects meta-analysis. A total of 26 articles were included in the metaanalysis after screening the titles, abstracts and full texts. The pooled results for a 1°C decrease of ambient temperature showed an increase of 0.31% (95% CI= 0.26 to 0.38) in cardiac biomarkers (p=0.00; I-squared=99.2%; Cochran's Q=5636.8). In contrast, the pooled results for a 1°C increase in ambient temperature showed an increase of 2.03% (95% CI= 1.08 to 3.82) in cardiac biomarkers (p=0.00; I-squared=95.7%; Cochran's Q=235.2). In the cardiovascular (CV) population, the percent increase in cardiac biomarkers levels due to a decrease/increase in ambient temperature was greater. This study showed the decrease/increase in ambient temperature has a direct correlation with the alterations in cardiac biomarkers. These findings are useful for managing temperatureassociated cardiovascular mortality.

Short-term effects of personal exposure to temperature variability on cardiorespiratory health based on subclinical non-invasive biomarkers

Growing literatures have explored the cardiorespiratory health effects of the daily temperature, but such effects of temperature variability remain unclear. We investigated the acute associations of personal levels of temperature variability with cardiorespiratory biomarkers. This is a panel study with four repeated measurements among forty eligible college students in Hefei, Anhui Province, China. We collected personal-level temperature data using temperature/humidity data loggers. Temperature variability parameters included diurnal temperature range (DTR), the standard-deviation of temperature (SDT) and temperature variability (TV). Cardiorespiratory health indicators included three BP parameters [systolic BP (SBP), diastolic BP (DBP) and mean article pressure (MAP)], fractional exhaled nitric oxide (FeNO), and four saliva biomarkers [C-reactive protein (CRP), cortisol, alpha-amylase and lysozyme]. Linear mixed-effect models were then used to assess the associations of temperature variability with these cardiorespiratory biomarkers. We found that short-term exposure to the three temperature variability parameters was associated with these cardiorespiratory biomarkers. The magnitude, direction and significance of these associations varied by temperature variability parameters, by biomarkers and by lags of exposure. Specifically, temperature variability parameters were inversely associated with BP and saliva lysozyme; positively associated with airway inflammation biomarkers (FeNO and saliva CRP) and stress response biomarkers (saliva cortisol and alpha-amylase). The results were robust to further control for air pollutants, and these associations were more prominent in females and in subjects with abnormal body mass index. Our findings suggested that acute exposure to temperature variability could significantly alter cardiorespiratory biomarker profiles among healthy young adults in China.

Effects of indoor and outdoor temperatures on blood pressure and central hemodynamics in a wintertime longitudinal study of Chinese adults

OBJECTIVES

We aimed to estimate the effects of indoor and outdoor temperature on wintertime blood pressure (BP) among peri-urban Beijing adults.

METHODS

We enrolled 1279 adults (ages: 40-89 years) and conducted measurements in two winter campaigns in 2018-2019 and 2019-2020. Study staff traveled to participant homes to administer a questionnaire and measure brachial and central BP. Indoor temperature was measured in the 5 min prior to BP measurement. Outdoor temperature was estimated from regional meteorological stations. We used multivariable mixed-effects regression models to estimate the within-individual and between-individual effects of indoor and outdoor temperatures on BP.

RESULTS

Indoor and outdoor temperatures ranged from 0.0 to 28 °C and -14.3 to 6.4 °C, respectively. In adjusted models, a 1 °C increase in indoor temperature was associated with decreased SBP [-0.4 mmHg, 95% confidence interval (CI): -0.7 to -0.1 (between-individual; brachial and central BP); -0.5 mmHg, 95% CI: -0.8 to -0.2 (within-individual, brachial BP); -0.4 mmHg, 95% CI: -0.7 to -0.2 (within-individual, central BP)], DBP [-0.2 mmHg, 95% CI:-0.4 to -0.03 (between-individual); -0.3 mmHg, 95% CI: -0.5 to -0.04 (within-individual)], and within-individual pulse pressure [-0.2 mmHg, 95% CI: -0.4 to -0.04 (central); -0.3 mmHg, 95% CI: -0.4 to -0.1 (brachial)]. Between-individual SBP estimates were larger among participants with hypertension. There was no evidence of an effect of outdoor temperature on BP.

CONCLUSION

Our results support previous findings of inverse associations between indoor temperature and BP but contrast with prior evidence of an inverse relationship with outdoor temperature. Wintertime home heating may be a population-wide intervention strategy for high BP and cardiovascular disease in China.

Can weather help explain 'why now?': The potential role of hourly temperature as a stroke trigger

BACKGROUND

While evidence suggests that daily ambient temperature exposure influences stroke risk, little is known about the potential triggering role of ultra short-term temperature.

METHODS

We examined the association between hourly temperature and ischemic and hemorrhagic stroke, separately, and identified any relevant lags of exposure among adult New York State residents from 2000 to 2015. Cases were identified via ICD-9 codes from the New York Department of Health Statewide Planning and Reearch Cooperative System. We estimated ambient temperature up to 36 h prior to estimated stroke onset based on patient residential ZIP Code. We applied a time-stratified case-crossover study design; control periods were matched to case periods by year, month, day of week, and hour of day. Additionally, we assessed effect modification by leading stroke risk factors hypertension and atrial fibrillation.

RESULTS

We observed 578,181 ischemic and 164,755 hemorrhagic strokes. Among ischemic and hemorrhagic strokes respectively, the mean (standard deviation; SD) patient age was 71.8 (14.6) and 66.8 (17.4) years, with 55% and 49% female. Temperature ranged from -29.5 °C to 39.2 °C, with mean (SD) 10.9 °C (10.3 °C). We found linear relationships for both stroke types. Higher temperature was associated with ischemic stroke over the 7 h following exposure; a 10 °C increase over 7 h was associated with 5.1% (95% Confidence Interval [CI]: 3.8, 6.4%) increase in hourly stroke rate. In contrast, temperature was negatively associated with hemorrhagic stroke over 5 h, with a 5-h cumulative association of -6.2% (95% CI: 8.6, -3.7%). We observed suggestive evidence of a larger association with hemorrhagic stroke among patients with hypertension and a smaller association with ischemic stroke among those with atrial fibrillation.

CONCLUSION

Hourly temperature was positively associated with ischemic stroke and negatively associated with hemorrhagic stroke. Our results suggest that ultra short-term weather influences stroke risk and hypertension may confer vulnerability.

Exposure to suboptimal ambient temperature during specific gestational periods and adverse outcomes in mice

Exposure to suboptimal ambient temperature during pregnancy has been reported as a potential teratogen of fetal development. However, limited animal evidence is available regarding the impact of extreme temperatures on maternal pregnancy and the subsequent adverse pregnancy outcomes. Our objective in this study is to investigate the relationship between temperature and maternal stress during pregnancy in mice. This study used the Naval Medical Research Institute (NMRI) mice during the second and third pregnant weeks with the gestational day (GD) (GD 6.5-14.5 and GD 14.5-17.5). Mice were exposed to suboptimal ambient temperature (1 °C, 5 °C, 10 °C, 15 °C, 40 °C, 42 °C, 44 °C, 46 °C, and 48 °C for the experimental group and 23 °C for the control group) 1 h per day, 7 days a weekin each trimester. Measurements of placental development (placental weight [PW] and placental diameter [PD]) and fetal growth (fetal weight [FW] and crown-to-rump length [CRL]) between experimental and control groups were compared using analysis of variance (ANOVA). Data on the occurrence of preterm birth (PTB) and abnormalities were also collected. The results showed that exposure to both cold and heat stress in the second and third weeks of pregnancy caused significant decreases in measurements of placental development (PW and PD) and fetal growth (FW and CRL). For all temperature exposures, 15 °C was identified as the optimal temperature in the development of the embryo. Most PTB occurrences were observed in high-temperature stress groups, with the highest PTB number seen in the exposure group at 48 °C, whereas PTB occurred only at 1 °C among cold stress groups. In the selected exposure experiments, an approximate U-shaped relation was observed between temperature and number of abnormality occurrence. The highest percentage of these anomalies occurred at temperatures of 1 °C and 48 °C, while no abnormalities were observed at 15 °C and in the control group. Our findings strengthened the evidence that exposure to suboptimal ambient temperatures may trigger adverse pregnancy outcomes and worsen embryo and fetal development in mice.

The effect of diurnal temperature range on blood pressure among 46,609 people in Northwestern China

BACKGROUND

A large number of studies have found a positive association between diurnal temperature range (DTR) and cardiovascular diseases (CVDs) incidence and mortality. Few studies regarding the effects of DTR on blood pressure (BP) are available.

OBJECTIVE

To investigate the effects of DTR on BP in Jinchang, northwestern China.

METHODS

Based on a prospective cohort research, a total of 46,609 baseline survey data were collected from 2011 to 2015. The meteorological observation data and environmental monitoring data were collected in the same period. The generalized additive model (GAM) was used to estimate the relationship between DTR and BP after adjusting for confounding variables.

RESULTS

Our study found that there was a positive linear correlation between DTR and systolic blood pressure (SBP) and plus pressure (PP), and a negative linear correlation between DTR and diastolic blood pressure (DBP). With a 1 °C increase of DTR, SBP and PP increased 0.058 mmHg (95%CI: 0.018-0.097) and 0.114 mmHg (95%CI: 0.059-0.168) respectively, and DBP decreased 0.039 mmHg (95%CI:-0.065 ~ -0.014). There was a significant interaction between season and DTR on SBP and PP. DTR had the greatest impact on SBP and PP in hot season. The association between DTR and BP varied significantly by education level.

CONCLUSION

There was a significant association between DTR and BP in Jinchang, an area with large temperature change at high altitudes in northwestern China. These results provide new evidence that DTR is an independent risk factor for BP changes among general population. Therefore, effective control and management of BP in the face of temperature changes can help prevent CVDs.

Influence of Absolute Humidity, Temperature and Population Density on COVID-19 Spread and Decay Durations: Multi-Prefecture Study in Japan

This study analyzed the spread and decay durations of the COVID-19 pandemic in different prefectures of Japan. During the pandemic, affordable healthcare was widely available in Japan and the medical system did not suffer a collapse, making accurate comparisons between prefectures possible. For the 16 prefectures included in this study that had daily maximum confirmed cases exceeding ten, the number of daily confirmed cases follow bell-shape or log-normal distribution in most prefectures. A good correlation was observed between the spread and decay durations. However, some exceptions were observed in areas where travelers returned from foreign countries, which were defined as the origins of infection clusters. Excluding these prefectures, the population density was shown to be a major factor, affecting the spread and decay patterns, with R² = 0.39 (p < 0.05) and 0.42 (p < 0.05), respectively, approximately corresponding to social distancing. The maximum absolute humidity was found to affect the decay duration normalized by the population density (R² > 0.36, p < 0.05). Our findings indicate that the estimated pandemic spread duration, based on the multivariate analysis of maximum absolute humidity, ambient temperature, and population density (adjusted R² = 0.53, p-value < 0.05), could prove useful for intervention planning during potential future pandemics, including a second COVID-19 outbreak.

'My blood pressure is low today, do you have the heating on?' The association between indoor temperature and blood pressure

OBJECTIVES

The independent association of indoor temperature with blood pressure (BP) is poorly understood and is not routinely considered in hypertension diagnosis or research. Questions remain as to whether the effect of indoor temperature on BP is confounded or modified by other factors.

METHODS

This study used data from the Health Survey for England 2014, consisting of 4659 community-dwelling adults aged 16 years and over, interviewed from January to December. Multivariable regression models were used to determine whether indoor temperature was related to levels of BP, and whether these relationships were confounded by other factors, including mean monthly outdoor temperature.

RESULTS

After controlling for confounding variables, a 1°C decrease in indoor temperature was associated with rises of 0.48 mmHg (95% confidence interval: -0.72 to -0.25) in SBP and 0.45 mmHg (95% confidence interval: -0.63 to -0.27) in DBP. The magnitude of association of indoor temperature with DBP and SBP was modified by physical activity. The indoor temperature-BP relationship was stronger in people who do not take physical activity regularly than people who exercise regularly.

CONCLUSION

The size of the independent association between indoor temperature and BP suggests it should be considered in the clinical management of hypertension and in hypertension research. Room temperature should also be considered as a modifiable risk factor in hypertension-related mortality and morbidity.

Productivity and physiological responses during exposure to varying air temperatures and clothing conditions

This study assessed the effects of clothing and air temperature combinations on workplace productivity and physiological response. Ten male Japanese subjects were exposed to six combinations of clothing (0.3 clo and 0.9 clo) and air temperature (16°C, 26°C, and 36°C) during which cognitive performance (Bourdon and calculation tests), manual motor performance (finger-tapping test), and physiological responses (heart rate, blood pressure, and skin and oral temperatures) were measured. Both cold exposure and lower clothing levels likely increased the Bourdon test performance. Calculation test performance tended to be affected by exposure to cold or neutral temperatures at the beginning of the test. Cold exposure undermined manual motor performance (especially when combined with fewer clothing items) while heat exposure significantly increased heart rate. Both cold exposure and higher clothing level during heat exposure increased blood pressure. Body temperature, particularly mean skin temperature, increased with higher air temperature and was significantly influenced by clothing insulation during cold exposure. These results provide novel evidence for the effects of clothing and air temperature (particularly cold) on human productivity and physiological responses in humans.

Clinical blood pressure responses to daily ambient temperature exposure in China: An analysis based on a representative nationwide population

BACKGROUND

Limited evidence is available regarding the potential heterogeneity of ambient temperature on blood pressure (BP) in various climate zones.

OBJECTIVES

To explore the effect of daily ambient temperature on BP in various climate zones across 31 provinces in China.

METHODS

A representative population sample (n = 451,770) were obtained from the China Hypertension Survey study (CHS) from October 2012 to December 2015. Survey seasons were divided into warm and cold seasons. Survey sites were divided into three climate zones as subtropical, temperate monsoon and temperate continental zones.

RESULTS

After adjustment for confounders, an overall 10 °C decrease in ambient temperature was statistically associated 0.74 mmHg (95% CI: 0.69, 0.79) and 0.60 mmHg (95% CI: -0.63, -0.57) rise for SBP and DBP, respectively. In the warm season, U-shaped exposure-response curves were observed between ambient temperature and BP in temperate monsoon and continental zones, and liner curves in other zones. A greater SBP change due to a lower temperature was observed in subtropical zones, so did DBP in temperate continental zones, especially for cold season. Female, rural and elderly populations were more susceptible to cold weather than their counterparts.

DISCUSSION

There is a geographical disparity between temperature and BP across different climate zones, which should been taken into consideration when maintaining stable blood pressure levels.

Acute effects of temperature exposure on blood pressure: An hourly level panel study

BACKGROUND

Several epidemiological studies have shown that blood pressure changes with temperature based on the daily temperature and linear relationship assumption. However, little is known about the true curve shape of the relationship between temperature and blood pressure.

OBJECTIVES

The objective of this study was to investigate the non-linear relationship between hourly temperature and blood pressure.

METHODS

This is a prospective panel study comprising 100 participants in Suzhou, China. The blood pressure of each participant was measured >50 times between October 2013 and January 2016. Hourly temperature data were derived from the nearest monitoring station owned by the China Meteorological Administration. A Distributed Lag Nonlinear Model (DLNM) was used to investigate the relationship between hourly temperature and blood pressure.

RESULTS

We found that the relationship between hourly temperature and blood pressure was parabolic. Short-term exposure to hourly temperatures had significant cold and heat effects on systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP), and mean arterial pressure (MAP). The hourly temperature had a significant lag effect on blood pressure, with a lag time of 0-5 h. Alcohol users were more sensitive to the cold effects of hourly temperature, and the diabetic population was more sensitive to the heat effects of hourly temperature on PP.

CONCLUSION

Temperature imparts short-term effects on blood pressure. Therefore, timely protective measures during cold waves or cold weather are beneficial to maintain stable blood pressure levels to reduce the risk of blood pressure related diseases.

The short-term effects of outdoor temperature on blood pressure among children and adolescents: finding from a large sample cross-sectional study in Suzhou, China

Although several studies have demonstrated a short-term association between outdoor temperature and blood pressure (BP) among various adult groups, evidence among children and adolescents is lacking. One hundred ninety-four thousand one hundred four participants from 2016 Health Promotion Program for Children and Adolescents (HPPCA) were analyzed through generalized linear mixed-effects models to estimate the short-term effects of two outdoor temperature variables (average and minimum temperature) on participants' BP. Decreasing outdoor temperature was associated with significant increases in systolic BP (SBP), diastolic BP (DBP), and prevalence of hypertension during lag 0 through lag 6. Additionally, daily minimum temperature showed a more apparent association with participants' BP. The estimated increases (95% confidence interval) in SBP and DBP at lag 0 were 0.82 (0.72, 0.92) mmHg and 2.28 (2.20, 2.35) mmHg for a 1 °C decrease in daily minimum temperature, while those values were 0.11 (0.10, 0.12) mmHg and 0.25 (0.24, 0.26) mmHg for a 1 °C decrease in daily average temperature, respectively. The effects of temperature on BP were stronger among female, as well as those with young age and low body mass index. It demonstrated that short-term decreases in outdoor temperature were significantly associated with rises in BP among children and adolescents. This founding has some implications for clinical management and research of BP. Meanwhile, public health intervention should be designed to reduce the exposure to cold temperature for protecting children and adolescents' BP.

Vulnerability to the Cardiovascular Effects of Ambient Heat in Six US Cities: Results from the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

With climate change, temperatures are increasing. Heat-associated health events disproportionately affect certain subpopulations. However, prior research has often lacked information on individual-level health and air conditioning and neighborhood stressors/protections.

OBJECTIVES

To assess whether (1) heat (2-day mean temperature above local 75th percentiles) is associated with increased heart rate and decreased blood pressure, controlling for age, time, season, daily ozone, and daily particulate matter (PM2.5) and (2) associations differ by antihypertensive medication use, renal function, fasting glucose, emotional support, air conditioning ownership and use, normalized difference vegetation index, neighborhood safety, and residence- specific oxides of nitrogen and PM2.5.

METHODS

Health and behavioral characteristics were obtained repeatedly on participants of the Multi-Ethnic Study of Atherosclerosis in six US sites (2000-2010). These were linked with airport temperature, air quality, and satellite- and survey-derived neighborhood characteristics. We used a fixed-effects design, regressing health outcomes on linear temperature splines with knots at the 75th percentiles, interaction terms for each characteristic, and adjustment for month of year, age, PM2.5, and ozone.

RESULTS

Overall, heat was not associated with heart rate. However, for a 2°C increase in heat, systolic blood pressure decreased by 1.1 mmHg (95% CI = -1.6, -0.6) and diastolic blood pressure by 0.3 mmHg (95% CI = -0.6, -0.1). Among nonusers of antihypertensive medications, heat-associated decreases in SBP were 2.1 mmHg greater among individuals with central air conditioning versus those without. Confidence intervals around the remaining modifiers were wide after multiple-comparisons corrections or sensitivity analyses.

CONCLUSIONS

Outdoor heat is associated with decreasing blood pressure, and cardiovascular vulnerability may vary primarily by ownership of central air conditioning.

Radial Pulse and Electrocardiography Modulation by Mild Thermal Stresses Applied to Feet: An Exploratory Study with Randomized, Crossover Design

OBJECTIVE

To investigate the changes in radial pulse induced by thermal stresses (TSs).

METHODS

Sixty subjects were enrolled. Using an open-label, 2×2 crossover randomization design, both feet of each subject were immersed in 15 °C water for cold stress (CS) and in 40 °C water for heat stress (HS) for 5 min each. Radial pulse, respiration and electrocardiogram (ECG) signals were recorded before, during and immediately after the TSs.

RESULTS

The analysis of heart rate variability revealed that CS increased the low-frequency (LF) and high-frequency (HF) components (P <0.05) and that HS reduced the LF and HF components (P <0.01). Both TSs reduced the normalized LF, increased the normalized HF, and reduced the LF/HF ratio. The differences in the ECG signals were more dominant during the TS sessions, but those in the radial pulse signals became more dominant immediately after the TS sessions. CS decreased the pulse depth (P <0.01) and increased the radial augmentation index (P <0.1), and HS increased the pulse pressure (P <0.1) and subendocardial viability ratio (P <0.01). There were no significant differences in pulse rate during the three time sequences of each TS. The respiration rate was increased (P <0.1), and the pulse rate per respiration (P/R ratio) was significantly decreased (P <0.05) with CS. The HF region (10-30 Hz) of the pulse spectral density was suppressed during both TSs.

CONCLUSIONS

CS induced vasoconstriction and sympathetic reactions, and HS induced vasodilation and parasympathetic reactions. Based on definitions used in pulse diagnosis, we made the novel discoveries that the pulse became slower (decreased P/R ratio), more floating and tenser under CS and that the HF region of the spectral power decreased significantly under both TSs.

Association between temperature and maternal stress during pregnancy

BACKGROUND

Maternal psychological stress during pregnancy has essentially been conceptualized as a teratogen. However, little is known about the effect of temperature on maternal stress during pregnancy. The aim of this study is to investigate the relationship between temperature and maternal stress during pregnancy.

METHODS

In 2010, a total of 1931 eligible pregnant women were enrolled across Shanghai from four prenatal-care clinics during their mid-to-late pregnancy. Maternal life-event stress and emotional stress levels during pregnancy were assessed by the "Life Event Scale for Pregnant Women" (LESPW) and "Symptom Checklist-90-Revised Scale" (SCL-90-R), respectively. Exposure to ambient temperature was evaluated based on daily regional average in different moving average and lag days. The generalized estimating equations were used to evaluate the relationship between daily average temperature/temperature difference and maternal stress.

RESULTS

After adjusting for relevant confounders, an U-shaped relationship was observed between daily average temperature and maternal Global-Severity-Index (GSI) of the SCL-90-R. Cumulative exposures to extremely low temperatures (< P5, 1.4-10.5℃, lag 0-1 days, 0-2 days and 0-5 days) and extremely high temperatures (≥ P95, 31.2-34.1℃, lag 0-1 days and 0-2 days), and acute exposures to extremely low (lag day 0, 1, 2 and 3) and high (lag day 0, 1) temperatures, all induced higher risks of high GSI (the highest tertile), compared to the risk induced by exposed to an optimal temperature range (20-25℃) (P< 0.05). Increased temperature difference was associated with high maternal GSI (P< 0.05). However, non-significant associations were observed between daily average temperatures/temperature differences and maternal log-transferred LESPW scores.

CONCLUSIONS

Cumulative and acute exposures to extremely low/high temperatures may both induce emotional stress during pregnancy.

Histone 3 modifications and blood pressure in the Beijing Truck Driver Air Pollution Study

CONTEXT

Histone modifications regulate gene expression; dysregulation has been linked with cardiovascular diseases. Associations between histone modification levels and blood pressure in humans are unclear.

OBJECTIVE

We examine the relationship between global histone concentrations and various markers of blood pressure.

MATERIALS AND METHODS

Using the Beijing Truck Driver Air Pollution Study, we investigated global peripheral white blood cell histone modifications (H3K9ac, H3K9me3, H3K27me3, and H3K36me3) associations with pre- and post-work measurements of systolic (SBP) and diastolic (DBP) blood pressure, mean arterial pressure (MAP), and pulse pressure (PP) using multivariable mixed-effect models.

RESULTS

H3K9ac was negatively associated with pre-work SBP and MAP; H3K9me3 was negatively associated with pre-work SBP, DBP, and MAP; and H3K27me3 was negatively associated with pre-work SBP. Among office workers, H3K9me3 was negatively associated with pre-work SBP, DBP, and MAP. Among truck drivers, H3K9ac and H3K27me were negatively associated with pre-work SBP, and H3K27me3 was positively associated with post-work PP.

DISCUSSION AND CONCLUSION

Epigenome-wide H3K9ac, H3K9me3, and H3K27me3 were negatively associated with multiple pre-work blood pressure measures. These associations substantially changed during the day, suggesting an influence of daily activities. Blood-based histone modification biomarkers are potential candidates for studies requiring estimations of morning/pre-work blood pressure.

The Influence of Thermal Comfort on the Quality of Life of Nursing Home Residents

Thermal comfort (TC) parameters were measured in 130 rooms from nursing homes (NH), following ISO 7730:2005 in order to evaluate the influence of winter season TC indices on quality of life (QoL) in older individuals. Mean radiant temperature (mrT), predicted mean vote (PMV) and predicted percent of dissatisfied people (PPD) indices, and the respective measurement uncertainties were calculated using Monte Carlo Method. The WHOQOL-BREF questionnaire was conducted from September 2012 to April 2013, during the winter season TC sampling campaign. Winter PMV and PPD indices showed significant differences between seasons in median values for comfort. There were also significant differences between seasons for air temperature, air velocity, mrT, and relative humidity. The winter PMV index displayed a "slightly cool" [≤-1] to "cool" [≤-2] in thermal sensation scale [-3 to 3]. PPD index reflected this discomfort as evidenced by a high rate of predicted dissatisfied occupants (64%). The influence of winter season TC on older individual QoL results demonstrated that values of PMV above -0.7 had higher mean score of QoL (coefficient estimate: 11.13 units) compared with values of PMV below -0.7. These findings are of relevance to public health and may be useful for understanding NH indoor environment variables thus implementing preventive policies in terms of standards and guidelines for these susceptible populations.

The impact of maternal factors on the association between temperature and preterm delivery

BACKGROUND

Few studies have examined maternal modifiers of temperature and adverse birth outcomes because of lack of data. We assessed the relationship between apparent temperature, preterm delivery (PTD) and maternal demographics, medical and mental health conditions, and behaviors.

METHODS

A time-stratified case-crossover analysis was conducted using 14,466 women who had a PTD (20 to less than 37 gestational weeks) from 1995 to 2009 using medical records from a large health maintenance organization in Northern California. Effect modifiers considered by stratification included several maternal factors: age, race/ethnicity, depression, hypertension, diabetes, smoking, alcohol use, pre-pregnancy body mass index, and Medicaid status. Apparent temperature data for women who had a monitor located within 20km of their residential zip codes were included. All analyses were stratified by warm (May 1 through October 31) and cold (November 1 through April 30) seasons.

RESULTS

For every 10°F (5.6°C) increase in average cumulative weekly apparent temperature (lag06), a greater risk was observed for births occurring during the warm season (11.63%; 95% CI: 4.08, 19.72%) compared to the cold season (6.18%; -2.96, 16.18%), especially for mothers who were younger, Black, Hispanic, underweight, smoked or consumed alcohol during pregnancy, or had pre-existing /gestational hypertension, diabetes, or pre-eclampsia.

CONCLUSIONS

Our findings suggest that warmer apparent temperatures exacerbate the risk of PTD, particularly for subgroups of more vulnerable women.

Environmental ambient temperature and blood pressure in adults: A systematic review and meta-analysis

OBJECTIVE

Although many individual studies have examined the association between temperature and blood pressure (BP), they used different methods and also their results were somewhat inconsistent. The aims of this study are to quantitatively summarize previous studies and to systematically assess the methodological issues to make recommendations for future research.

METHODS

We searched relevant empirical studies published before January 2016 concerning temperature and BP among adults using the MEDLINE, Embase and PubMed databases. Mean changes in systolic (SBP) and diastolic blood pressure (DBP) per 1°C reduction in temperature were pooled using a random-effects meta-analysis.

RESULTS

Of 23 studies included, 14 were used for meta-analysis. Consistent, statistically significant, inverse associations were observed between ambient temperature (mean, maximum, minimum outdoor temperature and indoor temperature) and BP. An 1°C decrease in mean daily outdoor temperature was associated with an increase in SBP and DBP of 0.26mmHg (95% CI: 0.18-0.33) and 0.13 (95% CI: 0.11-0.16), respectively. The increase was greater in people with conditions related to cardiovascular disease. An 1°C decrease in indoor temperature was associated with 0.38mmHg (0.18-0.58) increase in SBP, while the effects on DBP were not estimated due to limited studies. Among the previous studies on temperature-BP relationship, temperature and BP measurements are not accurate enough and statistical methods need to be improved.

CONCLUSIONS

Lower ambient temperatures seem to increase adults' BP and people with conditions related to cardiovascular disease are more susceptible to drops in temperature. Indoor temperature appeared to have a stronger effect on BP than outdoor temperature. To understand temperature-BP relationship well, a study combining repeated personal temperature exposure and ambulatory BP monitoring, applying improved statistical methods to examine potential non-linear relationship is warranted.

Fine-scale spatial and temporal variation in temperature and arrhythmia episodes in the VA Normative Aging Study

Many studies have demonstrated that cold and hot temperatures are associated with increased deaths and hospitalization rates; new findings indicate also an association with more specific cardiac risk factors. Most of these existing studies have relied on few weather stations to characterize exposures; few have used residence-specific estimates of temperature, or examined the exposure-response function. We investigated the association of arrhythmia episodes with spatial and temporal variation in temperature. We also evaluated the association btween monitored ambient temperature (central) and the same outcome. This longitudinal analysis included 701 older men participating in the VA Normative Aging Study. Arrhythmia episodes were measured as ventricular ectopy (VE) (bigeminy, trigeminy, or couplets episodes) by 4-min electrocardiogram (ECG) monitoring in repeated visits during 2000-2010. The outcome was defined as having or not VE episodes during a study visit. We applied a mixed-effect logistic regression model with a random intercept for subject, controlling for seasonality, weekday, medication use, smoking, diabetes status, body mass index, and age. We also examined effect modification by personal characteristics, confounding by air pollution, and the exposure-response function. For 1°C increase in the same day residence-specific temperature, the odds of having VE episodes was 1.10 (95% confidence interval [CI]: 1.04-1.17). The odds associated with 1°C increase in central temperature was 1.05 (95% CI: 1.02-1.09). The exposure-response function was nonlinear for averages of temperature, presenting a J-shaped pattern, suggesting greater risk at lower and higher temperatures. Increased warm temperature and decreased cold temperature may increase the risk of ventricular arrhythmias.

IMPLICATIONS

This is the first study to provide evidence that residence-specific temperature exposure is associated with increased risk of ventricular arrhythmias in cohort of elderly subjects without known chronic medical conditions; that the delayed effect of temperature has a nonlinear relationship; and therefore that both warm and cold temperature increase the risk of having ventricular arrhythmias. Moreover, we show that the use of residence-specific temperature data reduces downward bias due to exposure error, by comparing the estimated health effect based on our spatiotemporal exposure prediction model to those based on a single local weather monitor.

Short-term effects of air temperature on plasma metabolite concentrations in patients undergoing cardiac catheterization

BACKGROUND

Epidemiological studies have shown associations between air temperature and cardiovascular health outcomes. Metabolic dysregulation might also play a role in the development of cardiovascular disease.

OBJECTIVES

To investigate short-term temperature effects on metabolites related to cardiovascular disease.

METHODS

Concentrations of 45 acylcarnitines, 15 amino acids, ketone bodies and total free fatty acids were available in 2869 participants from the CATHeterization GENetics cohort recruited at the Duke University Cardiac Catheterization Clinic (Durham, NC) between 2001 and 2007. Ten metabolites were selected based on quality criteria and cluster analysis. Daily averages of meteorological variables were obtained from the North American Regional Reanalysis project. Immediate, lagged, and cumulative temperature effects on metabolite concentrations were analyzed using (piecewise) linear regression models.

RESULTS

Linear temperature effects were found for glycine, C16-OH:C14:1-DC, and aspartic acid/asparagine. A 5°C increase in temperature was associated with a 1.8% [95%-confidence interval: 0.3%; 3.3%] increase in glycine (5-day average), a 3.2% [0.1%; 6.3%] increase in C16-OH:C14:1-DC (lag of four days), and a -1.4% [-2.4%; -0.3%] decrease in aspartic acid/asparagine (lag of two days). Non-linear temperature effects were observed for alanine and total ketone bodies with breakpoint of 4°C and 20°C, respectively. Both a 5°C decrease in temperature on colder days (<4°C)and a 5°C increase in temperature on warmer days (≥4°C) were associated with a four day delayed increase in alanine by 6.6% [11.7; 1.8%] and 1.9% [0.3%; 3.4%], respectively. For ketone bodies we found immediate (0-day lag) increases of 4.2% [-0.5%; 9.1%] and 12.3% [0.1%; 26.0%] associated with 5°C decreases on colder (<20°C) days and 5°C increases on warmer days (≥20°C), respectively.

CONCLUSIONS

We observed multiple effects of air temperature on metabolites several of which are reported to be involved in cardiovascular disease. Our findings might help to understand the link between air temperature and cardiovascular disease.

Urban and transport planning, environmental exposures and health-new concepts, methods and tools to improve health in cities

BACKGROUND

The majority of people live in cities and urbanization is continuing worldwide. Cities have long been known to be society's predominant engine of innovation and wealth creation, yet they are also a main source of pollution and disease.

METHODS

We conducted a review around the topic urban and transport planning, environmental exposures and health and describe the findings.

RESULTS

Within cities there is considerable variation in the levels of environmental exposures such as air pollution, noise, temperature and green space. Emerging evidence suggests that urban and transport planning indicators such as road network, distance to major roads, and traffic density, household density, industry and natural and green space explain a large proportion of the variability. Personal behavior including mobility adds further variability to personal exposures, determines variability in green space and UV exposure, and can provide increased levels of physical activity. Air pollution, noise and temperature have been associated with adverse health effects including increased morbidity and premature mortality, UV and green space with both positive and negative health effects and physical activity with many health benefits. In many cities there is still scope for further improvement in environmental quality through targeted policies. Making cities 'green and healthy' goes far beyond simply reducing CO2 emissions. Environmental factors are highly modifiable, and environmental interventions at the community level, such as urban and transport planning, have been shown to be promising and more cost effective than interventions at the individual level. However, the urban environment is a complex interlinked system. Decision-makers need not only better data on the complexity of factors in environmental and developmental processes affecting human health, but also enhanced understanding of the linkages to be able to know at which level to target their actions. New research tools, methods and paradigms such as geographical information systems, smartphones, and other GPS devices, small sensors to measure environmental exposures, remote sensing and the exposome paradigm together with citizens observatories and science and health impact assessment can now provide this information.

CONCLUSION

While in cities there are often silos of urban planning, mobility and transport, parks and green space, environmental department, (public) health department that do not work together well enough, multi-sectorial approaches are needed to tackle the environmental problems. The city of the future needs to be a green city, a social city, an active city, a healthy city.

Outdoor Temperature, Heart Rate and Blood Pressure in Chinese Adults: Effect Modification by Individual Characteristics

We collected data from Kailuan cohort study from 2006 to 2011 to examine whether short-term effects of ambient temperature on heart rate (HR) and blood pressure (BP) are non-linear or linear, and their potential modifying factors. The HR, BP and individual information, including basic characteristics, life style, socio-economic characteristics and other characteristics, were collected for each participant. Daily mean temperature and relative humidity were collected. A regression model was used to evaluate associations of temperature with HR and BP, with a non-linear function for temperature. We also stratified the analyses in different groups divided by individual characteristics. 47,591 residents were recruited. The relationships of temperature with HR and BP were “V” shaped with thresholds ranging from 22 °C to 28 °C. Both cold and hot effects were observed on HR and BP. The differences of effect estimates were observed among the strata of individual characteristics. The effect estimate of temperature was higher among older people. The cold effect estimate was higher among people with lower Body Mass Index. However, the differences of effect estimates among other groups were inconsistent. These findings suggest both cold and hot temperatures may have short-term impacts on HR and BP. The individual characteristics could modify these relationships.

The acute effects of outdoor temperature on blood pressure in a panel of elderly hypertensive patients

Higher level of blood pressure (BP) in winter than in summer has been observed, but the association between temperature and BP and its potential modifiers with adjustment of individual confounders and time trends was rarely explored. We aimed to investigate the association between outdoor temperature and BP and its potential modification factors in a longitudinal panel study in Shanghai, China. From January 2011 to December 2012, we scheduled 54 follow-ups for BP measurements per subject via home visit every other week for 50 elderly hypertensive patients. We applied linear mixed-effect models to analyze the association between temperature and BP after controlling for individual characteristics, antihypertensive medication, comorbidities, and time trends. We evaluated the potential effect modifiers by stratification analyses. For a 1 °C decrease in the average temperature on concurrent day and previous day, systolic BP increased by 0.19 mmHg (95 % confidence interval = 0.06, 0.31) and diastolic BP increased by 0.12 mmHg (95 % confidence interval = 0.03, 0.21). The effect of temperature on BP was stronger among those with older age, female sex, low socioeconomic status, and obese physique. The effect was weak and even null for those taking the angiotensin receptor blockers, angiotensin-converting enzyme inhibitor, or its combination with calcium antagonists. Further, the effect was almost restricted within those having chronic comorbidities. Our results demonstrated that an acute decrease in outdoor temperature was significantly associated with a rise in BP among elderly hypertensive patients, in Shanghai, China. Individual characteristics, antihypertensive medications, and comorbidities may modify this effect.