Associations of ambient temperature with mortality for ischemic and hemorrhagic stroke and the modification effects of greenness in Shandong Province, China

Differentiating the impact of non-optimum temperature and temperature variability on cause-specific cerebrovascular mortality: An individual-level, case-crossover study in Shanghai, China

BACKGROUND

Cerebrovascular mortality exhibits seasonal variation, but the roles of temperature and temperature variability (TV) in cause-specific cerebrovascular mortality remain unclear.

METHODS

This individual-level time-stratified case-crossover research collected individual cerebrovascular death records during 2005-2021 in Shanghai, China. TV was calculated as the standard deviation of daily minimum and maximum temperature over consecutive days. Conditional logistic regression models combined with distributed lag nonlinear models were utilized to evaluate the cumulative exposure-response associations.

RESULTS

Based on a total of 388,823 cerebrovascular deaths, we found that exposure to extreme cold, extreme heat, and greater TV was significantly related to increased cause-specific cerebrovascular mortality. Extreme cold exhibited the strongest impact on hemorrhagic stroke [relative risk (RR) = 1.84; 95 % confidence interval (CI): 1.50, 2.26], followed by hemorrhagic stroke sequelae [1.75 (95 % CI: 1.25, 2.45)] and cerebrovascular sequelae [1.71 (95 % CI: 1.58, 1.86)]. Extreme heat showed the largest effect on cerebrovascular sequelae [1.35 (95 % CI: 1.29, 1.41)], followed by ischemic stroke sequelae [1.34 (95 % CI: 1.28, 1.41)]. TV was associated with the largest percentage increase in ischemic stroke sequelae [2.12 % (95 % CI: 1.35 %, 2.90 %)], followed by cerebrovascular sequelae [1.95 % (95 % CI: 1.23 %, 2.68 %)]. Stratified analyses revealed stronger associations in the elders, singles, and those with low education.

CONCLUSIONS

This case-crossover study provides the first-hand evidence that extreme temperatures and TV may elevate the risk of cause-specific cerebrovascular mortality, which underscore the urgency of implementing targeted protective measures for cerebrovascular patients facing extreme weather events, particularly among aging populations in megacities under climate change.

High temperature and ozone co-exposure induces cardiovascular damage in mice: Insights from gut microbiome and plasma metabolomics

Epidemiological studies have demonstrated associations between heat waves, ozone (O3) pollution, and cardiovascular morbidity and mortality. High temperature (HT) and higher levels of O3 usually co-exist in the atmosphere. However, few studies have investigated the adverse effects of HT and O3 co-exposure on cardiovascular system. Therefore, this study aimed to examine the effects of HT and O3 co-exposure on biomarkers of cardiovascular damage and potential mechanisms. Sixty-four healthy SPF male C57BL/6N mice, aged 8 weeks, were randomly allocated into four groups: control, O3, HT, and co-exposure (HT+O3). Mice inhaled filtered air or 1 ppm O3 at 24 °C or 36 °C, respectively, 4 h/day, for 5 consecutive days. Following the exposure, the biological samples of mice were collected for examination of biomarkers of cardiovascular disorders. Exposure to HT+O3 exacerbated cardiovascular pathological damage induced by HT or O3 alone. Compared to the control, the co-exposure group caused significant alterations of cardiovascular biomarkers. Moreover, co-exposure enhanced reduction of Lactobacillus and Ruminococcus and increases in Prevotella and Alistipe abundances induced by either HT or O3. Moreover, co-exposure also promoted O3-induced plasma metabolic disorder and these metabolites were enriched in multiple metabolic pathways typified by steroid hormone biosynthesis, biosynthesis of unsaturated fatty acids, and phenylalanine metabolism, among others. Spearman correlation analysis indicated that alterations of gut microbiota were significantly correlated with biomarkers of cardiovascular damage as well as plasma metabolic disorder. Exposure to HT and O3 leads to cardiovascular damage, which possibly implicates gut microbial dysbiosis and plasma metabolic disorder.

Exposure to greenness modifies the association between extreme temperature events and ischemic stroke recurrence in Tianjin, China

Few studies have found an association between extreme temperature events and an increased risk of recurrent ischemic stroke (IS). We examined associations between extreme temperature events (heat waves, cold spells) and recurrent IS risk in Tianjin, China (2019-2020), using a time-stratified case-crossover design, while evaluating greenness's moderating role. Significant heat wave effects peaked at lag 8, with severe intensity events increasing IS recurrence risk by 39.8% (OR = 1.398, 95% CI:1.032-1.894). Cold spell impacts peaked at lag 3, with moderate intensity cold spells elevating risk by 20.3% (OR = 1.203, 95% CI: 1.052-1.377) and severe intensity cold spells elevating risk by 98.2% (OR = 1.982, 95% CI: 1.407-2.791). Greenness modified these associations: low-greenness areas strengthened heat wave effects(lag9:OR = 2.309,95%CI:1.024-5.209) but weakened cold spell impacts(OR = 1.557,95%CI:1.037-2.340), whereas high-greenness areas attenuated heat wave links(lag8:OR = 1.402,95%CI:1.022-1.924) and nullified cold spell associations. Age and sex disparities emerged - younger individuals and males showed higher susceptibility to heat waves, while older individuals and males were more vulnerable to cold spells. The findings highlight greenness as a potential modifier of extreme temperature events-related IS recurrence risks and underscore demographic-specific vulnerabilities.

Estimating Heat-Related Mortality Burden Changes under Type-Specific Green and Blue Space Scenarios in China

BACKGROUND

Green and blue spaces (GBS) are assumed to mitigate heat-induced health risks. However, few studies have explored the impact of type-specific GBS changes on heat-related mortality burden.

OBJECTIVES

This study aimed to investigate the effect modifications of different GBS types on heat-related mortality risks, and to estimate the changes in mortality burden in multiple GBS scenarios.

METHODS

A case time-series study design was utilized based on the daily data on all-cause mortality and temperatures from 2009 to 2020 in 1,085 subdistricts in China. Mortality count data were obtained from the Zhejiang Center for Disease Control and Prevention. Meteorological data on temperature and relative humidity were acquired from the Zhejiang Meteorological Bureau. GBS exposure was assessed by integrating fine-scale population density, GBS boundary from Baidu and OpenStreetMap, and street-view image data from Baidu. Conditional Poisson regression analyses were conducted with the distributed lag nonlinear model, incorporating modifiers of type-specific GBS exposure. Changes in heat-attributable mortality under different GBS scenarios were also assessed.

RESULTS

Heat-related mortality risks were lower for populations with high exposure (95%) than for those with low exposure (5%) a) to overall green spaces, forests, parks, nature reserves, and street greenery, rather than to grasses, farms, and scrubs; and b) to overall blue spaces, lakes, and rivers, rather than reservoirs, wetlands, or coasts. Increases of 10%, 20%, and 30% exposure to overall green spaces are expected to avoid heat-related mortality burden by 1.6% [95% empirical confidence interval (eCI): 1.4, 1.9, 3.2% (95% eCI: 2.5, 3.9), and 4.8% (95% eCI: 3.5, 6.2)], respectively, whereas corresponding estimates for overall blue spaces are 5.4% (95% eCI: 4.4, 6.4), 10.8% (95% eCI: 8.5, 13.3), and 16.2% (95% eCI: 12.3, 20.5), respectively. Conversely, a 30% decrease in overall green space exposure and overall blue space exposure will increase the heat-related mortality burden by 4.8% (95% eCI: 4.3, 5.2) and 15.9% (95% eCI: 15.2, 16.7), respectively.

DISCUSSION

Our study revealed differences in the capacity of various GBS types to mitigate heat-related mortality risks. While the protective effects of GBS may be moderate, targeted planning strategies should prioritize their implementation for maximum benefits in mitigating heat-related health risks. The continuous shrinkage of the GBS would render other efforts futile, such as heat-health action plans. https://doi.org/10.1289/EHP14014.

Estimating the urban heat-related mortality burden due to greenness: a global modelling study

BACKGROUND

Heat exposure poses a substantial public health threat. Increasing greenness has been suggested as a mitigation strategy due to its cooling effect and potential to modify the heat-mortality association. This study aimed to comprehensively estimate the effects of increased greenness on heat-related deaths.

METHODS

We applied a multistage meta-analytical approach to estimate the potential reduction in global heat-related deaths by increasing greenness in the warm season in 2000-19 in 11 534 urban areas. We used the enhanced vegetation index (EVI) to indicate greenness and a random forest model to predict daily temperatures in counterfactual EVI scenarios. In the factual EVI scenarios, daily mortality and weather variables from 830 locations in 53 countries were extracted from the Multi-Country Multi-City Collaborative Research Network and used to assess heat-mortality associations. These associations were then extrapolated to each urban area under both factual and counterfactual EVI scenarios based on meta-regression models.

FINDINGS

We estimated that EVI increased by 10% would decrease the global population-weighted warm-season mean temperature by 0·08°C, EVI increased by 20% would decrease temperature by 0·14°C, and EVI increased by 30% would decrease temperature by 0·19°C. In the factual scenario, 3 153 225 (2·48%) of 127 179 341 total deaths could be attributed to heat exposure. The attributable fraction of heat-related deaths (as a fraction of total deaths) in 2000-19 would decrease by 0·67 (95% empirical CI 0·53-0·82) percentage points in the 10% scenario, 0·80 (0·63-0·97) percentage points in the 20% scenario, and 0·91 (0·72-1·10) percentage points in the 30% scenario, compared with the factual scenario. South Europe was modelled to have the largest decrease in attributable fraction of heat-related mortality.

INTERPRETATION

This modelling study suggests that increased greenness could substantially reduce the heat-related mortality burden. Preserving and expanding greenness might be potential strategies to lower ambient temperature and reduce the health impacts of heat exposure.

FUNDING

Australian Research Council and Australian National Health and Medical Research Council.

Small-area association of hourly ambient temperature and acute morbidity

Previous studies have reported the association between daily temperature and morbidity at city level, but small-area association of hourly temperature and acute morbidity is limited. We aimed to assess the association between hourly temperature and acute morbidity at the smallest administrative units (communities), and to explore the sources of regional heterogeneity. This case time series design was conducted using 145,678 non-accidental ambulance dispatch records in 328 communities in Fuzhou, China (2019-2024). Small-area associations between hourly temperatures and ambulance dispatches were assessed by quasi-Poisson regression with distributed lag nonlinear model. Multivariate meta-regressions used to explore modification of natural and social features. Unstandardized and standardized attributable number calculated for disease burden. We observed a U-shaped exposure-response curves of hourly temperature and risk of ambulance dispatches, with significantly adverse cold and heat effects referent at minimum risk temperature of 21 °C. The male and the elderly were more susceptible to non-optimal temperature. The unstandardized attributable numbers of non-accident ambulance dispatches due to cold and heat were 1,389 (95%eCI: 875, 1,748) and 590 (95%eCI: 319, 811), with corresponding standardized attribution number of 36 (95%eCI: 23, 46) and 15 (95%eCI: 8, 21). The standardized attributable number due to cold and heat were greater in the downtown and areas of higher proportions of the elderly and the higher population density, and lower NDVI level. High greenness mitigated heat-related adverse effects and temperature-related disease burden. The finding support the optimization of urbanized environment and public health strategies to reduce temperature-related disease burden under global warming.

Greenness, air pollution, and mortality risk: a retrospective cohort study of patients with lung cancer in China

The association between long-term exposure to air pollution and mortality from lung cancer has been established, yet evaluations of the potential mitigating effects of greenness on this impact are scarce. We conducted a cohort study in Pingyi County. A two-level Cox proportional hazards regression model was used to examine the associations among long-term exposure to air pollution, residential greenness, and lung cancer mortality. Among the examined pollutants, nitrogen dioxide exhibited the most significant adverse effects and highest risk of lung cancer mortality, with hazard ratio (HR) = 2.783 (95% confidence interval [CI]: 1.885-4.107) for all-cause mortality, HR = 2.492 (95%CI: 1.659-3.741) for tumour-related mortality, and HR = 2.431 (95%CI: 1.606-3.678) for lung cancer mortality. Higher greenness values were associated with a reduced risk of lung cancer mortality. These findings suggest the importance of implementing strategies for increasing greenness to reduce the health impacts of air pollution.

Association between short-term exposure to meteorological factors on hospital admissions for hemorrhagic stroke: an individual-level, case-crossover study in Ganzhou, China

BACKGROUND

Hemorrhagic stroke (HS) is associated with significant disability and mortality. However, the relationship between meteorological factors and hemorrhagic stroke, as well as the potential moderating role of these factors, remains unclear.

METHODS

Daily data on HS, air pollution, and meteorological conditions were collected from January 2015 to December 2021 in Ganzhou to analyze the relationship between meteorological factors and HS admissions. This analysis employed a time-stratified case-crossover design in conjunction with a distributional lag nonlinear model. Additionally, a bivariate response surface modelling was utilized to further investigate the interaction between meteorological factors and particulate matter. The study also stratified the analyses by gender and age. To investigate the potential impact of extreme weather conditions on HS, this study defined the 97.5th percentile as representing extremely high weather conditions, while the 2.5th percentile was classified as extremely low.

RESULTS

In single-day lags, the risk of admissions for HS was significantly associated with extremely low temperature (lag 1-2 and lag 13-14), extremely low humidity (lag 1 and lag 9-12), and extremely high precipitation (lag 2-7). Females exhibited greater susceptibility to extremely low temperature than males within the single-day lag pattern in the subcomponent layer, with a maximum relative risk (RR) that was 7% higher. In the cumulative lag analysis, the risk of HS admissions was significantly associated with extremely high temperature (lag 0-8∼lag 0-14), extremely low humidity (lag 0-2∼lag 0-14), and extremely high precipitation (lag 0-4∼lag 0-14). Within the cumulative lag day structure of the subcomponent layer, both extremely low and extremely high temperature had a more pronounced effect on females and aged ≥65 years. The risk of HS admissions was positively associated with extremely high barometric pressure in the female subgroups (lag 0-1 and lag 0-2). The highest number of HS admissions occurred when high PM2.5 concentrations coexisted with low precipitation.

CONCLUSIONS

Meteorological factors were significantly associated with the risk of hospital admissions for HS. Individuals who were female and aged ≥65 years were found to be more susceptible to these meteorological influences. Additionally, an interaction was observed between airborne particulate matter and meteorological factors. These findings contributed new evidence to the association between meteorological factors and HS.

Short-term ozone exposure on stroke mortality and mitigation by greenness in rural and urban areas of Shandong Province, China

BACKGROUND

Short-term exposure to ozone (O3) has been associated with higher stroke mortality, but it is unclear whether this association differs between urban and rural areas. The study aimed to compare the association between short-term exposure to O3 and ischaemic and haemorrhagic stroke mortality across rural and urban areas and further investigate the potential impacts of modifiers, such as greenness, on this association.

METHODS

A multi-county time-series analysis was carried out in 19 counties of Shandong Province from 2013 to 2019. First, we employed generalized additive models (GAMs) to assess the effects of O3 on stroke mortality in each county. We performed random-effects meta-analyses to pool estimates to counties and compare differences in rural and urban areas. Furthermore, a meta-regression model was utilized to assess the moderating effects of county-level features.

RESULTS

Short-term O3 exposure was found to be associated with increased mortality for both stroke subtypes. For each 10-µg/m3 (lag0-3) rise in O3, ischaemic stroke mortality rose by 1.472% in rural areas and 1.279% in urban areas. For each 0.1-unit increase in the Enhanced Vegetation Index (EVI) per county, the ischaemic stroke mortality caused by a 10-µg/m3 rise in O3 decreased by 0.60% overall and 1.50% in urban areas.

CONCLUSIONS

Our findings add to the evidence that short-term O3 exposure increases ischaemic and haemorrhagic stroke mortality and has adverse effects in urban and rural areas. However, improving greenness levels may contribute to mitigating the detrimental effects of O3 on ischaemic stroke mortality.

Modification effects of immigration status and comorbidities on associations of heat and heatwave with stroke morbidity

BACKGROUND

Heat and heatwave have been associated with stroke morbidity, but it is still unclear whether immigrants from different geographic regions and patients with comorbidity are more vulnerable to heat and heatwave.

METHODS

Time-stratified case-crossover design combined with generalized additive quasi-Poisson models were used to quantify the relative risks (RRs) of heat and heatwave on first-ever stroke morbidity during 0-7 lag days. Attributable fractions (AFs) were estimated to assess the first-ever stroke morbidity burden due to heat and heatwave. Stratified analyses for sex, age, disease subtypes, resident characteristics, and comorbidity type were performed to identify potential modification effects.

RESULTS

Heat and heatwave were associated with first-ever stroke morbidity, with the AF of 2.535% (95% empirical confidence interval (eCI) = 0.748, 4.205) and 2.409% (95% confidence interval (CI) = 1.228, 3.400), respectively. Among northern and southern immigrants, the AF for heat was 2.806% (0.031, 5.069) and 2.798% (0.757, 4.428), respectively, and the AF for heatwave was 2.918% (0.561, 4.618) and 2.387% (1.174, 3.398), respectively, but the effects of both on natives were statistically insignificant. Among patients with hypertension, dyslipidemia, or diabetes, the AF for heat was 3.318% (1.225, 5.007), 4.237% (1.037, 6.770), and 4.860% (1.171, 7.827), respectively, and the AF for heatwave was 2.960% (1.701, 3.993), 2.771% (0.704, 4.308), and 2.652% (0.653, 4.185), respectively. However, the effects of both on patients without comorbidity were statistically insignificant.

CONCLUSION

Heat and heatwave are associated with an increased risk of first-ever stroke morbidity among immigrants and those with comorbid hypertension, dyslipidemia, or diabetes, with the effects primarily due to non-native individuals.

DATA ACCESS STATEMENT

The author(s) are not authorized to share the data.

Associations between traffic-related air pollution and allergic rhinitis outpatient visits in three cities of Gansu Province

Emerging evidence indicates an increasing prevalence of allergic rhinitis (AR), potentially linked to air quality. The aim of the present study was to assess the relationship between traffic-related air pollutants (TRAPs) and outpatient visits for AR. Daily outpatient data for AR, air pollutant concentrations, and meteorological data were collected from January 2018 to December 2020 in Dingxi, Longnan, and Tianshui. Utilizing a Quasi-Poisson distribution, a generalized additive model (GAM) was employed in conjunction with distributed lag non-linear models (DLNM) to explore the association and lag effects of TRAPs on AR outpatient visits across the three cities. Stratified analyses based on gender, age, and season were conducted. A total of 11 106 outpatient visits for AR were recorded in the three cities. For an increase of 10 μg m-3 in PM2.5, the effect estimates in Dingxi, Longnan, and Tianshui reached their maximum at lag04, lag06, and lag07, respectively, with relative risk (RR) values of 4.696 (95% CI: 1.890, 11.614), 2.842 (95% CI: 2.102, 4.922), and 1.102 (95% CI: 1.066, 1.140). For NO2, the highest associations were exhibited in Dingxi (RR = 1.262, 95% CI: 1.081, 1.473) at lag07, in Longnan (RR = 2.554, 95% CI: 2.100, 4.805) at lag06, and in Tianshui (RR = 1.158, 95% CI: 1.106, 1.213) at lag07. Meanwhile, the strongest effects observed for a 1 mg m-3 increase in CO were 2.786 (95% CI: 1.467, 5.291) for Dingxi at lag07, 1.502 (95% CI: 1.096, 2.059) for Longnan at lag05, and 1.385 (95% CI: 1.137, 1.686) for Tianshui at lag04. Adults aged 15-64 years appeared to be more susceptible to TRAPs, and the associations were stronger in the cold season. The results of the present study indicate that exposure to TRAPs was positively correlated with outpatient visits for AR.

Association of ambient temperature on acute ischemic stroke in Yancheng, China

BACKGROUND

Acute ischemic stroke (AIS) is a major global public health issue. There is limited research on the relationship between ambient temperature and AIS hospital admissions, and the results are controversial. Our objective is to assess the short-term impact of ambient temperature on the risk of AIS hospital admissions in Yancheng, China.

METHODS

We collected data on daily AIS hospital admissions, meteorological factors, and air quality in Yancheng from 2014 to 2019. We used Poisson regression to fit generalized linear models and distributed lag non-linear models to explore the association between ambient temperature and AIS hospital admissions. The effects of these associations were evaluated by stratified analysis by sex and age.

RESULTS

From 2014 to 2019, we identified a total of 13,391 AIS hospital admissions. We observed that the influence of extreme cold and heat on admissions for AIS manifests immediately on the day of exposure and continues for a duration of 3-5 days. Compared to the optimal temperature (24.4 °C), the cumulative relative risk under extreme cold temperature (-1.3 °C) conditions with a lag of 0-5 days was 1.88 (95%CI: 1.28, 2.78), and under extreme heat temperature (30.5 °C) conditions with a lag of 0-5 days was 1.48 (95%CI: 1.26, 1.73).

CONCLUSIONS

There is a non-linear association between ambient temperature and AIS hospital admission risk in Yancheng, China. Women and older patients are more vulnerable to non-optimal temperatures. Our findings may reveal the potential impact of climate change on the risk of AIS hospital admissions.

Greenness mitigate cause-specific mortality associated with air pollutants in ischemic and hemorrhagic stroke patients: An ecological health cohort study

BACKGROUND

Air pollution is one of the most serious environmental risks to mortality of stroke. However, there exists a noteworthy knowledge gap concerning the different stroke subtypes, causes of death, the susceptibility of stroke patient, and the role of greenness in this context.

METHODS

We analyzed data from an ecological health cohort, which included 334,261 patients aged ≥40 years with stroke (comprising 288,490 ischemic stroke and 45,771 hemorrhagic stroke) during the period 2013-2019. We used Cox proportional hazards models with time-varying exposure to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) to assess the associations of annual average fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ozone (O3) with both all-cause and cause-specific mortality. Additionally, we conducted analyses to examine the effect modification by greenness and identify potential susceptibility factors through subgroup analyses.

RESULT

In multivariable-adjusted models, long-term exposure to PM2.5 and NO2 was associated with increased risk of all-cause mortality (HR: 1.038, 95% CI: 1.029-1.047 for PM2.5; HR: 1.055, 95% CI: 1.026-1.085 for NO2, per 10 μg/m3, for ischemic stroke patients; similar for hemorrhagic stroke patients). Gradually increasing effect sizes were shown for CVD mortality and stroke mortality. The HRs of mortality were slightly weaker with high versus low vegetation exposure. Cumulative exposures increased the HRs of pollutant-related mortality, and greater greenness decreased this risk. Two subtypes of stroke patients exhibited diverse patterns of benefit.

CONCLUSION

Increasing residential greenness attenuates the increased risk of mortality with different patterns due to chronic air pollutants for ischemic and hemorrhagic stroke, offering valuable insights for precise tertiary stroke prevention strategies.

Association of ambient ozone exposure and greenness exposure with hemorrhagic stroke mortality at different times: A cohort study in Shandong Province, China

Evidence on the association between long-term ozone exposure and greenness exposure and hemorrhagic stroke (HS) is limited, with mixed results. One potential source of this inconsistency is the difference in exposure time metrics. This study aimed to investigate the association between long-term exposure to ambient ozone, greenness, and mortality from HS using exposure metrics at different times. We also examined whether greenness exposure modified the relationship between ozone exposure and mortality due to HS. The study population consisted of 45771 participants aged ≥40 y residing in 20 counties in Shandong Province who were followed up from 2013 to 2019. Ozone exposure metrics (annual mean and warm season) and the normalized difference a measure of greenness exposure, were calculated. The relationship between environmental exposures (ozone and greenness exposures) and mortality from HS was assessed using time-dependent Cox proportional hazards models, and the modification of greenness exposure was examined using stratified analysis with interaction terms. The person-years at the end of follow-up were 90,663. With full adjustments, the risk of death from hemorrhagic stroke increased by 5% per interquartile range increase in warm season ozone [hazard ratio =1.05; 95 % confidence interval: 1.01-1.08]. No clear association was observed between annual ozone and mortality HS. Both the annual and summer NDVI were found to reduce the risk of HS mortality. The relationships were influenced by age, sex, and residence (urban or rural). Furthermore, greenness exposure was shown to have a modifying effect on the relationship between ozone exposure and the occurrence of HS mortality (P for interaction = 0.001). Long-term exposure to warm season O3 was positively associated with HS mortality, while greenness exposure was inversely associated with HS mortality. Greenness exposure may mitigate the negative effects of warm season ozone exposure on HS mortality.

Burden of Stroke Attributable to Nonoptimal Temperature in 204 Countries and Territories: A Population-Based Study, 1990-2019

BACKGROUND AND OBJECTIVES

Stroke attributable to nonoptimal temperature needs more attention with dramatic climate change. The aim of this study was to estimate the global burden and distribution characteristics of the burden.

METHODS

In this ecological study, we collected data from the Climate Research Unit Gridded Time Series, the World Bank databases, and the Global Burden of Diseases study to estimate the distribution of burden. We used the joinpoint model, decomposition analysis, age-period-cohort model, panel data analysis, and health inequality analysis to assess the different types of stroke burden attributable to different climatic conditions.

RESULTS

The burden of stroke attributable to nonoptimal temperature continued to grow, and aging was a key factor in this increase. In 2019, 521,031 (95% uncertainty interval [UI] 402,433-663,996) deaths and 9,423,649 (95% UI 7,207,660-12,055,172) disability-adjusted life years [DALYs] attributable to stroke due to nonoptimal temperature were recorded globally. Globally, men (age-standardized mortality rate [ASMR] 7.70, 95% UI 5.80-9.73; age-standardized DALY rate [ASDR] 139.69, 95% UI 102.96-178.54 in 2019) had a heavier burden than women (ASMR 5.89, 95% UI 4.50-7.60; ASDR 96.02, 95% UI 72.62-123.85 in 2019). Central Asia (ASMR 18.12, 95% UI 13.40-24.53; ASDR 327.35, 95% UI 240.24-440.61 in 2019) had the heaviest burden at the regional level. In the national level, North Macedonia (ASMR 32.97, 95% UI 20.57-47.44 in 2019) and Mongolia (ASDR 568.54, 95% UI 242.03-1,031.14 in 2019) had the highest ASMR/ASDR, respectively. Low temperature currently contributes to the main burden (deaths 474,002, 95% UI 355,077-606,537; DALYs 8,357,198, 95% UI 6,186,217-10,801,911 attributable to low temperature vs deaths 48,030, 95% UI 5,630-104,370; DALYs 1,089,329, 95% UI 112,690-2,375,345 attributable to high temperature in 2019). However, the burden due to high temperature has increased rapidly, especially among people aged older than 10 years, and was disproportionately concentrated in low sociodemographic index (SDI) regions such as Africa. In addition, the rapid increase in the stroke burden due to high temperature in Central Asia also requires special attention.

DISCUSSION

This is the first study to assess the global stroke burden attributed to nonoptimal temperature. The dramatic increase in the burden due to high temperature requires special attention, especially in low-SDI countries.

Heat and Cardiovascular Mortality: An Epidemiological Perspective

As global temperatures rise, extreme heat events are projected to become more frequent and intense. Extreme heat causes a wide range of health effects, including an overall increase in morbidity and mortality. It is important to note that while there is sufficient epidemiological evidence for heat-related increases in all-cause mortality, evidence on the association between heat and cause-specific deaths such as cardiovascular disease (CVD) mortality (and its more specific causes) is limited, with inconsistent findings. Existing systematic reviews and meta-analyses of epidemiological studies on heat and CVD mortality have summarized the available evidence. However, the target audience of such reviews is mainly limited to the specific field of environmental epidemiology. This overarching perspective aims to provide health professionals with a comprehensive overview of recent epidemiological evidence of how extreme heat is associated with CVD mortality. The rationale behind this broad perspective is that a better understanding of the effect of extreme heat on CVD mortality will help CVD health professionals optimize their plans to adapt to the changes brought about by climate change and heat events. To policymakers, this perspective would help formulate targeted mitigation, strengthen early warning systems, and develop better adaptation strategies. Despite the heterogeneity in evidence worldwide, due in part to different climatic conditions and population dynamics, there is a clear link between heat and CVD mortality. The risk has often been found to be higher in vulnerable subgroups, including older people, people with preexisting conditions, and the socioeconomically deprived. This perspective also highlights the lack of evidence from low- and middle-income countries and focuses on cause-specific CVD deaths. In addition, the perspective highlights the temporal changes in heat-related CVD deaths as well as the interactive effect of heat with other environmental factors and the potential biological pathways. Importantly, these various aspects of epidemiological studies have never been fully investigated and, therefore, the true extent of the impact of heat on CVD deaths remains largely unknown. Furthermore, this perspective also highlights the research gaps in epidemiological studies and the potential solutions to generate more robust evidence on the future consequences of heat on CVD deaths.

Associations between cold spells of different time types and coronary heart disease severity

Limited evidence showed the association between cold spells and the severity of coronary heart disease (CHD). This study was to investigate the association between cold spells with their different time types and CHD severity. We collected data on CHD patients admitted to the Zhongnan Hospital, Wuhan, China from 2016 to 2021. CHD severity was quantified using the SYNTAX score and transformed into a binomial variable. Daily mean, maximum and minimum temperature were collected during the study period. We first used daily mean temperature to find the optimum definition among multiple thresholds and durations. The daily maximum and minimum temperatures were used to define different types of cold spells (daytime, nighttime and compound) based on the optimum definition. Annual cold spell days were included to assess individual exposure to cold spells. Logistic regression models were performed to fit the association between cold spell days and CHD severity stratified by different tertiles of PM2.5 and NDVI. In this study, 1937 CHD patients were included. The cold spell defined as at least four consecutive days with daily mean temperature below the 5th percentile exhibited the optimum model. We found that a 4-day increase in cold spell days was associated with more severe CHD (OR = 1.170, 95% CI: 1.074, 1.282). Such an association was more pronounced under higher levels of PM2.5 by OR = 1.270 (1.086, 1.494) and lower levels of greenness by OR = 1.240 (1.044, 1.476). Compared with daytime and compound cold spells, nighttime cold spells showed the strongest association with CHD severity by OR = 1.141 (1.026, 1.269). This study showed that exposure to cold spells was positively associated with CHD severity, especially the nighttime cold spells. The association between cold spells and CHD severity was more significant in high levels of PM2.5 and low levels of greenness.

Hourly Heat Exposure and Acute Ischemic Stroke

Importance

Previous studies have demonstrated the associations of daily high temperature with hospitalizations and mortality from ischemic stroke, but the hourly association of ambient heat and acute ischemic stroke (AIS) onset has been rarely examined.

Objectives

To evaluate the association between hourly high ambient temperature and the onset of AIS.

Design, Setting, and Participants

This time-stratified case-crossover study was conducted using a nationwide registry that collects data from more than 200 stroke centers in China. Participants were adult patients with AIS who were hospitalized in the warm seasons between January 1, 2019, and December 31, 2021.

Exposures

Hourly temperature and single-hour temperature exposure lag up to 24 hours before the AIS onset (lag 0 hours to lag 24 hours).

Main Outcomes and Measures

The main outcome was onset of AIS. Associations between hourly mean temperatures and AIS onset were analyzed using conditional logistic regression integrated with the distributed lag nonlinear model. Stratification analyses were applied to examine potential association modifiers. Several sensitivity analyses were conducted to examine the robustness of the results.

Results

A total of 82 455 patients with AIS (mean [SD] age, 65.8 [11.9] years; 52 267 males [63.4%]) were included in the final analysis. A monotonically increasing risk of AIS onset was associated with higher temperatures. The excess AIS risk occurred immediately at lag 0 hours and persisted for 10 hours. Compared with the reference temperature (12.1 °C), the cumulative odds ratio (OR) over lag 0 to 10 hours of AIS onset associated with extremely high temperature (33.3 °C) was 1.88 (95% CI, 1.65-2.13) nationwide. The exposure-response curve was steeper in the north than in the south (OR, 1.80 [95% CI, 1.53-2.11] vs 1.57 [95% CI, 1.31-1.87]). The ORs were greater for males and patients with a history of dyslipidemia or atrial fibrillation, but the differences were not significant.

Conclusions and Relevance

Results of this study suggest that hourly heat exposure is associated with increased risk of AIS onset. This finding may benefit the formulation of public health strategies to reduce cerebrovascular risk associated with high ambient temperature under global warming.

Global burden of non-optimal temperature attributable stroke: The long-term trends, population growth and aging effects

Since the 20th century, the world has undergone climate change, population growth and population aging, which may result in alterations in the epidemiology of non-optimal temperature-associated strokes. We employed multiple methodologies and data from the global burden of disease 2019 to unveil the long-term curvilinear trends in strokes attributed to non-optimal temperature and the impact of aging and population growth on its changing epidemiology. From 1990 to 2019, the age-standardized DALYs rate (ASDR) of strokes attributable to low temperature had been decreasing, but from 2016, the continued downward trend in ASDR disappeared and began to remain stable. On the contrary, the ASDR of strokes attributable to high temperature continued to increase. The high socio-demographic index (SDI) region experienced the fastest decreased trend. The disease burden of stroke attributable to low temperature is increased by aging in 178 countries (87.25%), compared with 130 (63.73%) for high temperature. After excluding aging and population growth, the DALY rate for strokes attributed to high temperature was increasing in 87 countries and territories (42.64%). The disease burden of strokes attributed to low temperature is far greater than that of high temperature in absolute figures. However, globally, there is a significant trend toward an increase in strokes attributed to high temperature. Social development has largely offset the burden of strokes attributed to low temperature, but most regions of the world are equally affected by strokes attributed to high temperature. Simultaneously, in the framework of climate change, aging is also largely hindering stroke prevention efforts.

Associations of long-term exposure to air pollution and green space with reproductive hormones among women undergoing assisted reproductive technology: A longitudinal study

Studies investigating the association between long-term exposure to air pollution (AP)/green space and female reproductive hormones are still limited. Furthermore, their interactive effects remain unclear. Our study sought to explore the separate and interactive impacts of AP/green space on reproductive hormones among women undergoing assisted reproductive technology. We measured estradiol (E2), progesterone (P), testosterone (T), and follicle-stimulating hormone (FSH) from the longitudinal assisted reproduction cohort in Anhui, China. The annual mean concentrations of air pollutants were calculated at the residential level. Normalized Difference Vegetation Index (NDVI) within 500-m represented green space exposure. To assess the effect of AP/green space on hormones, we employed multivariable linear mixed-effect models. Our results showed that each one-interquartile range (IQR) increment in particulate matter (PM2.5 and PM10) and sulfur dioxide (SO2) was associated with -0.03[-0.05, -0.01], -0.03[-0.05, -0.02], and -0.03[-0.05, -0.01] decrease in P. An IQR increase in PM2.5, PM10, SO2, and carbon monoxide (CO) was associated with a -0.16[-0.17, -0.15], -0.15[-0.16, -0.14], -0.15[-0.16, -0.14], and -0.12[-0.13, -0.11] decrease in T and a -0.31[-0.35, -0.27], -0.30[-0.34, -0.26], -0.26[-0.30, -0.22], and -0.21[-0.25, -0.17] decrease in FSH. Conversely, NDVI500-m was associated with higher levels of P, T, and FSH, with β of 0.05[0.02, 0.08], 0.06[0.04, 0.08], and 0.07[0.00, 0.14]. Moreover, we observed the "U" or "J" exposure-response curves between PM2.5, PM10, and SO2 concentrations and E2 and P levels, as well as "inverted-J" curves between NDVI500-m and T and FSH levels. Furthermore, we found statistically significant interactions of SO2 and NDVI500-m on E2 and P as well as CO and NDVI500-m on E2. These findings indicated that green space might mitigate the negative effects of SO2 on E2 and P, as well as the effect of CO on E2. Future research is needed to determine these findings and underlying mechanisms.

The Green Heart Project: Objectives, Design, and Methods

The Green Heart Project is a community-based trial to evaluate the effects of increasing greenery on urban environment and community health. The study was initiated in 2018 in a low-to-middle-income mixed-race residential area of nearly 28,000 residents in Louisville, KY. The 4 square mile area was surveyed for land use, population characteristics, and greenness, and assigned to 8 paired clusters of demographically- and environmentally matched "target" (T) and adjacent "control" (C), clusters. Ambient levels of ultrafine particles, ozone, oxides of nitrogen, and environmental noise were measured in each cluster. Individual-level data were acquired during in-person exams of 735 participants in Wave 1 (2018-2019) and 545 participants in Wave 2 (2021) to evaluate sociodemographic and psychosocial factors. Blood, urine, nail, and hair samples were collected to evaluate standard cardiovascular risk factors, inflammation, stress, and pollutant exposure. Cardiovascular function was assessed by measuring arterial stiffness and flow-mediated dilation. After completion of Wave 2, more than 8,000 mature, mostly evergreen, trees and shrubs were planted in the T clusters in 2022. Post planting environmental and individual-level data were collected during Wave 3 (2022) from 561 participants. We plan to continue following changes in area characteristics and participant health to evaluate the long-term impact of increasing urban greenery.

Ambient temperatures associated with reduced cognitive function in older adults in China

The cognitive function status of older adults determines the social function and living quality of older adults, which is related to the healthy development and stability of the society. However, the impact of high or low ambient temperature on cognitive function in older adults remains unclear. Based on data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS), we comprehensively assessed the impact of ambient temperature on the cognitive function of older adults in this study. The findings exhibited that for each 1 °C ascent in monthly temperature of high temperature, the examination score of global cognitive function of older adults decreased by 0.48 (95% CI 0.21-0.74), which was greater than that of 0.14 (95% CI 0.06-0.25) for each 1 °C reduction in low temperature. Overall, the detrimental effect of high temperature on cognitive function in older adults was more significant than that of low temperature, including on the five sub-cognitive functions involved. Our research provides vital technical guidance and reference for the health protection and prevention of cognitive function of older adults in specific external environmental conditions under the current climatic variation and temperature rise.

Burden of stroke attributable to high ambient temperature from 1990 to 2019: A global analysis

AIMS

To determine the global and regional burden of stroke due to high temperature and the spatiotemporal trends in 204 countries and territories from 1990 to 2019.

METHODS

Based on Global Burden of Disease Study 2019, deaths, disability-adjusted life years (DALYs), and age-standardized mortality rate (ASMR) and age-standardized DALY rate (ASDR) for stroke attributable to high temperature (i.e. a daily mean temperature warmer than the theoretical minimum-risk exposure level (TMREL)) were calculated in global, geographical location, and country and analyzed by age, sex, subtypes, and socio-demographic index (SDI) from 1990 to 2019. The trends in ASMR and ASDR from 1990 to 2019 were estimated by linear regression model. The regression coefficients (β) referred to a mean change of per year for ASMR or ASDR attributable to high temperature.

RESULTS

The global burden of stroke attributable to high temperature had an increase trend from 1990 to 2019 (β = 0.005, 95% uncertainty interval (UI) = 0.003-0.007 for ASMR and β = 0.104, 95% UI = 0.066-0.142 for ASDR, respectively). Globally, in 2019, an estimated 0.048 million deaths and 1.01 million DALYs of stroke were attributable to high temperature, and the global ASMR and ASDR of stroke attributable to high temperature were 0.60 (95% UI = 0.07-1.30) and 13.31 (1.40-28.97) per 100,000 population, respectively. The largest burden occurred in Western Sub-Saharan Africa, followed by South Asia, Southeast Asia, and North Africa and the Middle East. ASMR and ASDR increased with age and were higher in males and for intracerebral hemorrhage, and were the highest in the low SDI regions. In 2019, the region with the largest percentage increase in ASMR and ASDR attributable to high temperature was Eastern Sub-Saharan Africa from 1990 to 2019.

CONCLUSIONS

Stroke burden due to high temperature has been increasing, and a higher burden was observed in people aged 65-75 years, males, and countries with a low SDI. Stroke burden attributable to high temperature constitutes a major global public health concern in the context of global warming.

Association Between Long-Term Exposure to Fine Particulate Matter Constituents and Progression of Cerebral Blood Flow Velocity in Beijing: Modifying Effect of Greenness

Few studies have explored the effects of fine particulate matter (PM2.5) and its constituents on the progression of cerebral blood flow velocity (BFV) and the potential modifying role of greenness. In this study, we investigated the association of PM2.5 and its constituents, including sulfate (SO4 2-), nitrate (NO3 -), ammonium (NH4 +), organic matter (OM), and black carbon (BC), with the progression of BFV in the middle cerebral artery. Participants from the Beijing Health Management Cohort who underwent at least two transcranial Doppler sonography examinations during 2015-2020 were recruited. BFV change and BFV change rate were used to define the progression of cerebral BFV. Linear mixed effects models were employed to analyze the data, and the weighted quantile sum regression assessed the contribution of PM2.5 constituents. Additionally, greenness was examined as a modifier. Among the examined constituents, OM exhibited the strongest association with BFV progression. An interquartile range increase in PM2.5 and OM exposure concentrations was associated with a decrease of -16.519 cm/s (95% CI: -17.837, -15.201) and -15.403 cm/s (95% CI: -16.681, -14.126) in BFV change, and -10.369 cm/s/year (95% CI: -11.387, -9.352) and -9.615 cm/s/year (95% CI: -10.599, -8.632) in BFV change rate, respectively. Furthermore, stronger associations between PM2.5 and BFV progression were observed in individuals working in areas with lower greenness, those aged under 45 years, and females. In conclusion, reducing PM2.5 levels in the air, particularly the OM constituent, and enhancing greenness could potentially contribute to the protection of cerebrovascular health.

Potential role of ambient temperature as a trigger for intracerebral hemorrhage: a time-stratified case-crossover study in Tianjin, China

The adverse effects of ambient temperature on human health are receiving increasing attention, yet evidence of its impact on intracerebral hemorrhage (ICH) onset is limited. Here, the relationship between ambient temperature and ICH was evaluated. A time-stratified case-crossover analysis was performed based on 4051 ICH patients admitted to five stroke units in Tianjin between January 2014 and December 2020. Conditional logistic regression was applied to evaluate the associations between the daily mean temperature (Tm) or daily temperature range (DTR) and ICH onset. We found a negative association between Tm and ICH onset (OR = 0.977, 95% CI 0.968-0.987) but not between DTR and ICH onset. In stratified analyses, men and individuals aged ≥ 60 years were more susceptible to low-ambient temperature effects; corresponding adjusted ORs were 0.970 (95% CI 0.956-0.983) and 0.969 (95% CI 0.957-0.982), respectively. Tm significantly affected patients with deep ICH (OR = 0.976, 95% CI 0.965-0.988), but had no effect on lobar ICH. There was also seasonal heterogeneity in the effect of Tm on ICH onset, with Tm being negatively associated with ICH onset only in the warm season (OR = 0.961, 95% CI 0.941-0.982). Results suggest that the low-ambient temperature might trigger ICH onset, especially for the male and elderly population, providing important health guidance to prevent cold exposure-induced ICH.