Effects of extreme temperature events on deaths and its interaction with air pollution

BACKGROUND

Both extreme temperature events (ETEs) and air pollution affected human health, and their effects were often not independent. Previous studies have provided limited information on the interactions between ETEs and air pollution.

METHODS

We collected data on deaths (non-accidental, cardiovascular, and respiratory) in Zibo City along with daily air pollution and meteorological data from January 2015 to December 2019. Distributed lag non-linear model was used to explore the health effects of ETEs on deaths. Non-parametric binary response model, hierarchical model and joint effect model were used to further explore the interaction between ETEs and air pollution in different seasons. Meanwhile, subgroup analysis by gender and age (≥ 65 years old and < 65 years old) was conducted to identify the vulnerable population.

RESULTS

ETEs increased death risk, especially for cardiovascular and respiratory deaths. Heat waves had a stronger impact than cold spells. Cold spells had a longer lag and fluctuating trend. Heat waves had a short-term impact, followed by a decrease. Females and those aged ≥ 65 were more affected, but subgroup differences were not significant. During ETEs and non-ETEs, there were different effects on deaths with per IQR increase in air pollutant concentrations. Joint effect models revealed that there was a significant interaction between ETEs and air pollution on non-accidental deaths. The interaction between PM2.5 and cold spells was antagonistic in the cold season. In the warm season, the health effects of heat waves and high O3 concentration were enhanced. The relative excess risk due to interaction (RERI) of cold spells and PM2.5 in total population was -0.09 (95 % CI: -0.17, -0.01), and 9 % (95 % CI: 1 %, 17 %) of the total effect was attributable to interaction. Subgroup analysis confirmed the interactions in females and those aged ≥ 65.

CONCLUSIONS

Significant association observed between ETEs and deaths. Females and ≥ 65 age groups were vulnerable. There were interactions between ETEs and air pollution. The effect of PM2.5 on deaths decreased during cold spells, while the effect of O3 increased during heat waves. In addition to improving air quality, it is necessary to further strengthen the prevention and control of ETEs.

Biometeorological conditions during cold spells in south-east Poland and west Ukraine

The aim of this research is to analyze the biometeorological conditions, based on the Physiologically Equivalent Temperature (PET) thermal index, during cold spells (CSs) in south-east Poland and west Ukraine during the years 1966-2021. The research shows a high variability of the occurrence of CSs in the study period and a clear increase in the frequency and total duration of CSs in the east of the study area. The number of CSs in the analyzed years varies from 6 cases in the west (in Katowice) to 34 in the east of the study area (in Shepetivka). The total duration of CSs varied from 26 days (in Raciborz and Katowice) to 166 days (in Rivne). At the majority of stations, CSs occurred most frequently in the first two decades (1966/1967-1975/1976, 1976/1977-1985/986) and in the last full decade (2006/2007-2015/2016). The average PET values at 12:00 UTC during CSs decreased eastwards throughout the study domain and were generally lower than -20.0 °C in the west of Ukraine, while in south-east Poland varied between -18.1 and -20.0 °C. At 40% of stations across the study domain, the lowest average PET values were recorded during a cold spell in January 1987, with PET values varying from -28.0 °C in Chernivtsi to -12.7 °C in Yaremche. The longest or one of the longest spells in most stations (in 77% of stations across the study domain) was the cold spell of 2012 and characterized by mean PET values ranging from -25.4 °C in Rivne to -19.5 °C in Zakopane.

Space-time clusters of cardiovascular mortality and the role of heatwaves and cold spells in the city of São Paulo, Brazil

The effects extreme air temperature events are related with an increase in cardiovascular mortality among vulnerable groups worldwide. Therefore, we identify spatiotemporal mortality clusters associated with diseases of the cardiovascular system among people ≥ 65 years in São Paulo, from 2006 to 2015, and investigate whether high-risk mortality clusters occurred during or following extreme air temperature events. To detect the clusters, we used daily mortality data and a retrospective space-time scan analysis with a discrete Poisson model. Extreme air temperature events were defined by daily mean temperatures, below the 10th percentile for cold spells and above the 90th percentile for heatwaves, with two or more consecutive days. We found statistically significant high-risk mortality clusters located in the peripheral areas. The spatiotemporal clusters of risk areas for cardiovascular and ischemic heart disease occurred during or following cold spell events, whereas those for stroke and ischemic stroke events were related to heatwaves.

Short-term effects of cold spells on hematocrit among adults in Nanjing, China: A distributed-lagged effect analysis

BACKGROUND

Previous studies have linked exposure to cold spells with cardiovascular diseases, however, underlying mechanisms remained to be understood. We aimed to explore the short-term effects of cold spells on hematocrit, a blood indicator associated with cardiovascular disease.

METHODS

Our study was performed among 50,538 participants (68,361 health examination records) who visited the health examination centers of Zhongda Hospital in Nanjing City, China, during the cold seasons from 2019 to 2021. Data on meteorology and air pollution were obtained from the China Meteorological Data Network and the Nanjing Ecological Environment Bureau, respectively. Cold spells in this study were defined as daily mean temperatures (Tmean) <3rd or 5th percentile with two or more consecutive days. Linear mixed-effect models combined with distributed lag nonlinear models were applied to estimate associations of cold spells with hematocrit.

RESULTS

Cold spells were found to be significantly correlated with increased hematocrit on lag 0 to 26 days. Moreover, the cumulative effects of cold spells on hematocrit remained significant at varying lag days. These single and cumulative effects were robust across different definitions of cold spells and conversions of hematocrit. For instance, cold spells (Tmean <3rd percentile) at lags 0, 0-1, and 0-27 days were significantly associated with 0.09 [95 % confidence interval (CI): 0.03, 0.15], 0.17 (95 % CI: 0.07, 0.28), and 3.71 (95 % CI: 3.06, 4.35) - unit (%) increases in original hematocrit, respectively. In subgroup analyses, stronger effects of cold spells on hematocrit were observed in females and participants aged 50 years or over.

CONCLUSION

Cold spells have significant immediate and longer-lagged effects (up to 26 days) on hematocrit. Females and individuals aged 50 years or over are more sensitive to cold spells. These findings might provide a new perspective for exploring the effects of cold spells on adverse cardiac events.

Association between cold spells and serum lipid levels among the elders: a distributed-lagged effects analysis

Little evidence about the effects of cold spells on serum lipid levels is available. The aim of this study was to explore the association between cold spells and serum lipid levels among the elders in Jinan, China. Data of old adults from health check-up program in Shandong Provincial Qianfoshan Hospital was collected for this study. Linear mixed models combined with distributed lag nonlinear models were used to examine the relationship between cold spells and serum lipid levels, considering the confounding effects of age, sex, blood pressure, body mass index, and other meteorological factors. Subgroup analysis by gender and analysis based on different definitions of cold spells were also conducted. Increased TG levels in lag 0-lag 2 days and decreased TG levels in lag 5-lag 8 days after cold spells were observed among the elders. The largest increase was 0.363 mmol/L (95% CI: 0.184 ~ 0.543) in lag 0 day, while the largest decreased TG levels was 0.083 mmol/L (95% CI: 0.147 ~ 0.019) in lag 6 day. Similar results were obtained in the analysis of different sex and based on different definitions of cold spells. However, no significant association was found between cold spells with TC, LDL-C, and HDL-C. This study indicates that cold spells were significantly associated with serum TG levels in the elders. Effective preventive measures should be implemented around the cold spells to reduce the volatility of serum lipid levels and the occurrence of subsequent cardiovascular diseases.

Impacts of heatwaves and cold spells on glaucoma in rural China: a national cross-sectional study

China faces increasing health risks from climate change. The structure and function of the eye and vision were affected by extreme heat and cold. The study aimed to evaluate the impacts of heatwaves and cold spells on glaucoma. A national cross-sectional study of the Rural Epidemiology for Glaucoma (REG-China) was conducted in ten provinces of China, and 36,081 adults aged 40 years or more were included. Glaucoma signs were assessed via a standard examination. A total of 15 heatwave definitions, based on intensity (95th to 99th percentiles of temperature distribution) and duration (≥2 days, 3 days, and 4 days), were used to quantify heatwave effects, and 6 cold spell definitions were defined based on threshold temperature percentile (5th and 10th) and duration (3 days, 5 days, and 9 days). Multivariable-adjusted logistic regression models paired with interaction analysis were performed to investigate the impacts of heatwaves and cold spells on glaucoma, and the dose-response relationships were assessed using a restricted cubic spline (RCS) model. Subgroup analysis was conducted stratified by gender, age, smoking status, occupation, and family history of glaucoma. The overall prevalence of glaucoma was 2.1% (95% CI 1.94-2.25%). Higher heatwaves were significantly correlated with higher OR of glaucoma, with the OR (95% CI) ranging from 1.014 (1.009, 1.018) to 1.090 (1.065, 1.115) by different definitions. Glaucoma was affected by heatwaves more strongly than by cold spells. The effects of both heatwaves and cold spells were higher in males than females and in smokers than nonsmokers. These results of the present study evoked the attention of prospective research to elucidate the relationship between extreme temperatures and eye diseases.

Impact of cold spells on COPD mortality in Jiangsu Province, China

Ambient cold is associated with substantial population attributable fraction of mortality in China, and respiratory health is vulnerable to cold exposure. This study aimed to examine the effect of cold spells on risk of deaths from chronic obstructive pulmonary disease (COPD). We collected daily data on deaths from COPD and climatic factors from 1 January 2016 to 31 December 2019 in 13 cities of Jiangsu Province, China. We used a quasi-Poisson generalized linear model coupled with a distributed lag non-linear model to quantify the association between risk of COPD deaths and exposure to cold spells (defined as 2 or more consecutive days with mean temperature ≤ 5^th percentile of daily mean temperature distribution in cold months). Stratification analyses by age, sex, education, and occupation were undertaken to identify vulnerable subgroups. The results suggested that exposure to cold spells was associated with a higher risk of COPD deaths in Lianyungang (relative risk (RR): 1.70; 95% confidence interval (CI): 1.31, 2.21), Nanjing (RR: 1.54; 95% CI: 1.16, 2.04), Nantong (RR: 1.97; 95% CI: 1.68, 2.31), Suzhou (RR: 1.97; 95% CI: 1.55, 2.50), Suqian (RR: 1.68; 95% CI: 1.23, 2.29), Taizhou (RR: 1.70; 95% CI: 1.32, 2.19), Wuxi (RR: 1.99; 95% CI: 1.53, 2.60), Xuzhou (RR: 1.71; 95% CI: 1.01, 2.90), Yancheng (RR: 1.78; 95% CI: 1.53, 2.06), Yangzhou (RR: 2.78; 95% CI: 2.06, 3.76), and Zhenjiang (RR: 1.79; 95% CI: 1.26, 2.55). All subgroups seemed to be vulnerable to the effect of cold spells. The recommendation of this study is that individuals with pre-existing COPD, regardless of age, sex, education, or occupation, should be made aware of the health risk posed by cold spells and should be encouraged to take cold adaptation actions before cold season arrives. The main limitation of this study is that it is subject to ecological fallacy.

Increased emergency cases for out-of-hospital cardiac arrest due to cold spells in Shenzhen, China

Cold spells have been associated with specific diseases. However, there is insufficient scientific evidence on the effects of cold spells on out-of-hospital cardiac arrest (OHCA). Data on OHCA cases and on meteorological factors and air pollutants were collected between 2013 and 2020. We adopted a quasi-Poisson generalized additive model with a distributed lag nonlinear model (DLNM) to estimate the effect of cold spells on daily OHCA incidence. Backward attributable risk within the DLNM framework was calculated to quantify the disease burden. We compared the effects and OHCA burden of cold spells using nine definitions. The risks of different cold spells on OHCA increased at higher intensities and longer durations. Based on Akaike's information criterion for the quasi-Poisson regression model and the attributable risk, the optimal cold spell was defined as a period in the cold month when the daily mean temperature was below the 10th percentile of the temperature distribution in the study period for at least 2 days. The single-day effect of the optimal cold spell on OHCA occurred immediately and lasted for approximately 1 week. The maximum single-day effect was 1.052 (95% CI: 1.018-1.087) at lag0, while the maximum cumulative effect was 1.433 (95% CI:1.148-1.788) after a 14-day lag. Men were more susceptible to cold spells. Young and middle-aged people were affected by cold spells similar to the elderly. Cold spells can increase the risk of OHCA with an approximately 1-week lag effect. Health regulators should take more targeted measures to protect susceptible populations during cold weather.

Impact of ambient temperature, precipitation and seven years of experimental warming and nutrient addition on fruit production in an alpine heath and meadow community

Alpine and polar regions are predicted to be among the most vulnerable to changes in temperature, precipitation, and nutrient availability. We carried out a seven-year factorial experiment with warming and nutrient addition in two alpine vegetation communities. We analyzed the relationship between fruit production and monthly mean, maximum, and min temperatures during the fall of the pre-fruiting year, the fruiting summer, and the whole fruit production period, and measured the effects of precipitation and growing and thawing degree days (GDD & TDD) on fruit production. Nutrient addition (heath: 27.88 ± 3.19 fold change at the end of the experiment; meadow: 18.02 ± 4.07) and combined nutrient addition and warming (heath: 20.63 ± 29.34 fold change at the end of the experiment; meadow: 18.21 ± 16.28) increased total fruit production and fruit production of graminoids. Fruit production of evergreen and deciduous shrubs fluctuated among the treatments and years in both the heath and meadow. Pre-maximum temperatures had a negative effect on fruit production in both communities, while current year maximum temperatures had a positive impact on fruit production in the meadow. Pre-minimum, pre-mean, current mean, total minimum, and total mean temperatures were all positively correlated with fruit production in the meadow. The current year and total precipitation had a negative effect on the fruit production of deciduous shrubs in the heath. GDD had a positive effect on fruit production in both communities, while TDD only impacted fruit production in the meadow. Increased nutrient availability increased fruit production over time in the high alpine plant communities, while experimental warming had either no effect or a negative effect. Deciduous shrubs were the most sensitive to climate parameters in both communities, and the meadow was more sensitive than the heath. The difference in importance of TDD for fruit production may be due to differences in snow cover in the two communities.

Increased hospital admissions for asthma from short-term exposure to cold spells in Beijing, China

BACKGROUND

There is a paucity of studies investigating extreme cold events and asthma exacerbations. This study examined whether an association exists between cold spells and daily hospital admissions for asthma in Beijing, China from 2012 to 2016.

METHODS

Daily hospital admissions for asthma, meteorological variables and air quality data were collected during 2012-2016 in Beijing. A cold spell was defined as a period of at least two consecutive days with the daily mean temperature below or at the 5th percentile (-7 °C) in cold seasons (November to March) during the study period. We applied a time-series design using quasi-Poisson regression combined with a distributed lag model to estimate the risk of asthma hospital admissions associated with cold spells. Stratified analyses by gender and age groups were conducted to identify the potential susceptible subpopulations to cold spells. We also explored the effect modification by air quality by dividing the daily air quality index (AQI) into two levels (high and low) based on the median value.

RESULTS

Cold spells increased the risk of asthma hospital admissions, with the maximum cumulative relative risk (CRR) over three weeks (Lag0-21) in the total population. The highest single-day relative risk (RR) was found on the days of cold spells (Lag0) with the RR = 1.059 (95% CI: 1.008-1.113), and the CRR at Lag0-21 was 1.333 (95% CI: 1.049-1.693). Across different gender and age groups, younger people (<65 years) were more sensitive to cold spells. No significant effect modification by AQI was detected.

CONCLUSION

Short-term exposure to cold spells is associated with an increased risk of hospital admissions for asthma in Beijing. During the cold spells, younger people aged <65 years were at particular risk for asthma exacerbations. Our results suggest that extreme cold events have a significant impact on asthma.

The short-term effects of cold spells on pediatric outpatient admission for allergic rhinitis in Hefei, China

BACKGROUND

Some studies have reported that cold weather is associated with the development of allergic rhinitis (AR), but the study of extreme cold temperatures and AR is scarced. This study was conducted to find out the optimal definition of the cold spells in Hefei and to explore the relationship between cold spells and childhood AR, further to identify potential susceptible populations.

METHODS

Data of daily AR, meteorological variables and air pollutants from January 1, 2014 to December 31, 2016 were collected in Hefei. Poisson generalized linear regression with a distributed-lag nonlinear model (DLNM) was used to explore the relationship between cold spells and daily pediatric outpatient with allergic rhinitis, by comparing the number of the admission during the cold spells with those during non-cold spells in cold seasons (December to April), after adjusting for relative humidity, air pollutants, seasonality, long-term trends, calendar month, holiday and day of the week (DOW).

RESULTS

All definitions of cold spells both had a certain impact on children with allergic rhinitis, and the trend of their effects was similar. The optimal cold spells was defined as the daily average temperature for below 10th with two consecutive days during the study period, and the greatest impact of cold spells was at lag0, with a 12.5% (95%CI: 6.3%-19.1%) increase of AR than non-cold spell days, and its impact could last for 2 days. Male children, children aged 5-18 years and non-scattered children were considered to be more vulnerable to AR in cold spell days.

CONCLUSIONS

There was evidence showed that the cold spells may significantly increase the pediatric outpatient admission for allergic rhinitis, especially for male children, children aged 5-18 years and non-scattered children. For the serious threat posed by cold spells, caregivers and health practitioners should strengthen their awareness of the prevention of vulnerable people.

Misfortunes never come singly: Consecutive weather shocks and mortality in Russia

This paper examines the impacts of extremely hot and cold days on mortality in Russia, using a 25-year regional panel data. Unlike other studies, the sequence of those extreme days is also taken into account, that is, the impacts of both single and consecutive (i.e. heat waves and cold spells) extreme days are estimated simultaneously. We demonstrate the importance of accounting for the sequence of extreme days. We also disentangle the impacts of those extremes by age and gender. The findings suggest that single hot days increase mortality, while single cold days do not affect mortality. On the other hand, both consecutive hot and consecutive cold days increase mortality in females and males for all age groups, although males are affected more severely. Overall, consecutive days with extreme temperatures impose considerable costs to society in terms of years of life lost. Thus, ignoring the sequences of extreme days that are likely to increase in the future because of climate change may have critical implications for mitigation policies.

In the light of change: a mixed methods investigation of climate perceptions and the instrumental record in northern Sweden

Significant climate change in the Arctic has been observed by indigenous peoples and reported in scientific literature, but there has been little research comparing these two knowledge bases. In this study, Sami reindeer herder interviews and observational weather data were combined to provide a comprehensive description of climate changes in Northern Sweden. The interviewees described warmer winters, shorter snow seasons and cold periods, and increased temperature variability. Weather data supported three of these four observed changes; the only change not evident in the weather data was increased temperature variability. Winter temperatures increased, the number of days in cold periods was significantly reduced, and some stations displayed a 2 month-shorter snow cover season. Interviewees reported that these changes to the wintertime climate are significant, impact their identity, and threaten their livelihood. If consistency between human observations of changing weather patterns and the instrumental meteorological record is observed elsewhere, mixed methods research like this study can produce a clearer, more societally relevant understanding of how the climate is changing and the impacts of those changes on human well-being.

Ambient temperature during gestation and cold-related adult mortality in a Swedish cohort, 1915-2002

For all climatic regions, mortality due to cold exceeds mortality due to heat. A separate line of research indicates that season of birth predicts lifespan after age 50. This and other literature implies the hypothesis that ambient temperature during gestation may influence cold-related adult mortality. We use data on over 13,500 Swedes from the Uppsala Birth Cohort Study to test whether cold-related mortality in adulthood varies positively with unusually benign ambient temperature during gestation. We linked daily thermometer temperatures in Uppsala, Sweden (1915-2002) to subjects beginning at their estimated date of conception and ending at death or the end of follow-up. We specified a Cox proportional hazards model with time-dependent covariates to analyze the two leading causes of cold-related death in adulthood: ischemic heart disease (IHD) and stroke. Over 540,450 person-years, 1313 IHD and 406 stroke deaths occurred. For a one standard deviation increase in our measure of warm temperatures during gestation, we observe an increased hazard ratio of 1.16 for cold-related IHD death (95% confidence interval: 1.03-1.29). We, however, observe no relation for cold-related stroke mortality. Additional analyses show that birthweight percentile and/or gestational age do not mediate discovered findings. The IHD results indicate that ambient temperature during gestation--independent of birth month--modifies the relation between cold and adult mortality. We encourage longitudinal studies of the adult sequelae of ambient temperature during gestation among populations not sufficiently sheltered from heat or cold waves.