Heat Wave Period Research Articles

Calls for Help: Using Ambulance Calls as an Indicator of Heat Wave Outcomes

Calls for Help: Using Ambulance Calls as an Indicator of Heat Wave OutcomesAbstract Number:1613 Gulrez Shah Azhar*, Ajit Rajiva, Priya Dutta, Abhiyant Tiwari, and Dileep Mavalankar Gulrez Shah Azhar* Public Health Foundation of India, India, E-mail Address: [email protected] Search for more papers by this author , Ajit Rajiva Public Health Foundation of India, India, E-mail Address: [email protected] Search for more papers by this author , Priya Dutta Public Health Foundation of India, India, E-mail Address: [email protected] Search for more papers by this author , Abhiyant Tiwari Public Health Foundation of India, India, E-mail Address: [email protected] Search for more papers by this author , and Dileep Mavalankar Public Health Foundation of India, India, E-mail Address: [email protected] Search for more papers by this author AbstractIntroduction: Heat, a major cause of weather related mortality in the world, causes morbidity and mortality by either direct or indirect effects of thermal stress on the body. Direct effects include a spectrum of heat illness ranging from heat exhaustion to heat stroke, while indirectly the underlying strain on physiological systems can result in other manifestations such as renal insufficiency, acute cerebrovascular disease, and exacerbations of co-morbid conditions. We did a risk-assessment to characterizes heat wave’s impacts on mortality and morbidity and assess potential population health risks associated with extreme heat exposure.Methods: Using temperature data obtained from the National Climatic Data Centre, ambulance call data obtained from GVK-EMRI and mortality data obtained from the registrar of births and deaths. Comparisons across time and against each other were made to ascertain the relationships between the variables and the May 2010 heat wave in Ahmedabad. Time periods of interest included the heat wave days of 19th to 25th May 2010, the daily reports for the summer months of March, April and May and annual figures of the years 2009, 2010 and 2011.Results: A time-series shows a visual correlation between mortality, morbidity and temperature. For temperatures equal to or above 42°C, a linear correlation between ambulance calls and mortality is seen (R2 =0.834). There is a significant increase in the number of ambulance calls related to unconsciousness, respiratory complaints and fevers (P<0.001) during the heat wave period from 19 to 25 May, 2010. The respiratory complaints increased to 4.62 times the normal.Conclusion: Ambulance call complaints are an important indicator of heat related health outcomes given that they can be analysed quicker and closer to the point of origin than mortality data. For temperatures above 42°C, the relationships between all 3 variables studied show that heat is a key factor in influencing morbidity and mortality.

The effects of horizontal advection on the urban heat island in Birmingham and the West Midlands, United Kingdom during a heatwave

Birmingham is the second most populous city in the United Kingdom and observations indicate that it has a pronounced urban heat island (UHI), i.e. higher ambient temperatures in the city centre compared with surrounding suburban and rural areas, particularly at night. The effects of UHIs are often amplified during anticyclonic summer weather conditions, which can cause or exacerbate heatwaves. Enhanced temperatures in highly populated regions can mean that significant numbers of people are at risk from heat‐related illness during hot weather. Climate change projections often do not include the effects of the UHI, which can mean that assessments of heat‐related health effects using these projections underestimate the actual magnitude of future health impacts. We present numerical simulations of the UHI in Birmingham and the West Midlands Metropolitan region during the heatwave of August 2003 using the high‐resolution, regional meteorological Weather Research and Forecasting (WRF) model, with an urban canopy scheme. We evaluated the model using local air‐temperature observations, and found good model performance in capturing the temporal and spatial signature of the UHI. We performed a sensitivity test, replacing urban land categories with rural ones, and found that the difference in temperature between the two model runs throughout the heatwave period (2–11 August 2003) was around 3°C on average, and reached a maximum of 7°C. Finally, we present a novel generic methodology to enable the examination of the extent of horizontal advection of warm air downwind of the conurbation area. We found that during the heatwave, temperatures downwind of Birmingham were up to 2.5°C warmer than those upwind. This methodology has the potential for improvements to, or parametrizations for, diagnostic models that do not explicitly include dynamics and where local conditions are driven largely by land‐surface type.

Socio‐demographic vulnerability to heatwave impacts in Brisbane, Australia: a time series analysis

ObjectiveExamining the association between socioeconomic disadvantage and heat‐related emergency department (ED) visits during heatwave periods in Brisbane, 2000–2008. MethodsData from 10 public EDs were analysed using a generalised additive model for disease categories, age groups and gender. ResultsCumulative relative risks (RR) for non‐external causes other than cardiovascular and respiratory diseases were 1.11 and 1.05 in most and least disadvantaged areas, respectively. The pattern persisted on lags 0–2. Elevated risks were observed for all age groups above 15 years in all areas. However, with RRs of 1.19–1.28, the 65–74 years age group in more disadvantaged areas stood out, compared with RR=1.08 in less disadvantaged areas. This pattern was observed on lag 0 but did not persist. The RRs for male presentations were 1.10 and 1.04 in most and less disadvantaged areas; for females, RR was 1.04 in less disadvantaged areas. This pattern persisted across lags 0–2. ConclusionsHeat‐related ED visits increased during heatwaves. However, due to overlapping confidence intervals, variations across socioeconomic areas should be interpreted cautiously. ImplicationsED data may be utilised for monitoring heat‐related health impacts, particularly on the first day of heatwaves, to facilitate prompt interventions and targeted resource allocation.

Heat waves and mortality in Frankfurt am Main, Germany, 2003-2013: what effect do heat-health action plans and the heat warning system have?

Following the heat wave of August 2003 that caused over 70,000 fatalities in Western Europe, heat-health action plans (HHAP) and heat warning systems were implemented in many European countries, including Germany. The effect of these preventive measures (informing the population as well as nursing and medical personnel) on excess mortality during heat waves in Frankfurt am Main, Germany, is studied, taking into account newly published data on a modifying effect of air pollution on heat mortality. Mortality data comprising all deaths registered in the city of Frankfurt was obtained from the statistical state office; air temperature and air pollution data in Frankfurt Ost were obtained from the Hessian state office for environment and geology. SPSS Version 15 was used for statistical analysis (bivariate and partial correlations, nonparametric tests/Kruskal-Wallis, and Mann-Whitney test). Temperature data as well as air pollution and daily mortality exhibited extreme values in summer 2003 compared to the summer periods 2004-2013. Never again were such levels of temperature and air pollution reached. In 2003, excess mortality was 78%, and as high as 113% among the population aged >80 years. During the heat wave of 2010, the total excess mortality was 23% (significant) and 38% in the population aged >80 years, while during heat waves in 2006 and 2013 no significant increase in total mortality was seen (total excess mortality 12% and 4%; not significant). Lower excess mortality could be seen in Frankfurt am Main during heat waves following the implementation of HHAP and the heat warning system. This might be an effect of the measures implemented by the HHAP to reduce heat mortality. However, it cannot be ruled out that this might also be an effect of shorter heat wave periods and lower air pollution in the subsequent years. Therefore, further efforts are needed to improve the resilience of the population, especially the elderly population, to better cope with heat waves.

The impact of heatwaves on workers׳ health and safety in Adelaide, South Australia

This study aims to investigate the impact of heatwaves on worker׳s health and safety; to identify workers at higher risk of prevalent illnesses and injuries due to heatwaves; and to provide evidence for policy-makers and service providers. South Australian workers׳ compensation claims data for 2001–2010 were transformed into time series format, merged with meteorological data and analysed using generalized estimating equation (GEE) models. For total injury claims there was no significant difference detected between heatwave and non-heatwave periods. However, for outdoor industries, daily claims increased significantly by 6.2% during heatwaves. Over-represented in hot weather were male labourers and tradespersons aged ≥55 years, and those employed in ‘agriculture, forestry and fishing’ and ‘electricity, gas and water’. Occupational burns, wounds, lacerations, and amputations as well as heat illnesses were significantly associated with heatwaves. Similarly, moving objects, contact with chemicals, and injuries related to environmental factors increased significantly during heatwaves, especially among middle-aged and older male workers. With the predicted increase of extremely hot weather, there is a need for relevant adaptation and prevention measures at both practice and policy levels for vulnerable work groups.

Effect of Exposure to Heatwave During Blastocyst Formation on Reproductive Performance of Female Rabbits

We examined the effect of female exposure to heatwave during blastocyst formation on their reproductive performance and its effect on transcriptome in blastocyst and endometrial tissue. In this study, a total of 72 rabbit does were artificially inseminated and divided into two environmental groups 2 days later: does under conventional conditions (maintained between 14-22°C, n = 29) and does heat stressed in a climatic chamber (maintained between 32-37°C, n = 43). The heat-stressed group were kept under these conditions for 3 days and returned to conventional conditions thereafter. Five days post-insemination, 48 does were slaughtered to collect blastocyst and endometrium samples. mRNA transcripts from OCT-4, VEGF, erbB3, Ifn-ɣ, HSP70 and HSP90 were analysed by qRT-PCR. At day 12 of gestation, 24 females were examined by laparoscopy to evaluate implanted embryos and at birth the total kits born and individual weights were recorded. Results revealed no gene expression changes in blastocyst and endometrial tissue under heatwave exposure. Moreover, our results demonstrated that rabbit embryos developed from 8-16 cells to blastocyst during a heatwave did not affect implantation rates, total number of kits born and foetal losses. In summary, these results demonstrate that heatwave period is not a critical point in the reproductive performance of rabbits during blastocyst formation.

The effectiveness of cool and green roofs as urban heat island mitigation strategies

Mitigation of the urban heat island (UHI) effect at the city-scale is investigated using the Weather Research and Forecasting (WRF) model in conjunction with the Princeton Urban Canopy Model (PUCM). Specifically, the cooling impacts of green roof and cool (white/high-albedo) roof strategies over the Baltimore-Washington metropolitan area during a heat wave period (7 June–10 June 2008) are assessed using the optimal set-up of WRF-PUCM described in the companion paper by Li and Bou-Zeid (). Results indicate that the surface UHI effect (defined based on the urban–rural surface temperature difference) is reduced significantly more than the near-surface UHI effect (defined based on urban–rural 2 m air temperature difference) when these mitigation strategies are adopted. In addition, as the green and cool roof fractions increase, the surface and near-surface UHIs are reduced almost linearly. Green roofs with relatively abundant soil moisture have comparable effect in reducing the surface and near-surface UHIs to cool roofs with an albedo value of 0.7. Significant indirect effects are also observed for both green and cool roof strategies; mainly, the low-level advection of atmospheric moisture from rural areas into urban terrain is enhanced when the fraction of these roofs increases, thus increasing the humidity in urban areas. The additional benefits or penalties associated with modifications of the main physical determinants of green or cool roof performance are also investigated. For green roofs, when the soil moisture is increased by irrigation, additional cooling effect is obtained, especially when the ‘unmanaged’ soil moisture is low. The effects of changing the albedo of cool roofs are also substantial. These results also underline the capabilities of the WRF-PUCM framework to support detailed analysis and diagnosis of the UHI phenomenon, and of its different mitigation strategies.

Increased risk of emergency hospital admissions for children with renal diseases during heatwaves in Brisbane, Australia

Heatwaves have a significant impact on population health including both morbidity and mortality. In this study we examined the association between heatwaves and emergency hospital admissions (EHAs) for renal diseases in children (aged 0-14 years) in Brisbane, Australia. Daily data on EHAs for renal diseases in children and exposure to temperature and air pollution were obtained for Brisbane city from January 1, 1996 to December 31, 2005. A time-stratified case-crossover design was used to compare the risks for renal diseases between heatwave and non-heatwave periods. There were 1565 EHAs for renal diseases in children during the study period. Heatwaves exhibited a significant impact on EHAs for renal diseases in children after adjusting for confounding factors (odds ratio: 3.6; 95% confidence interval: 1.4-9.5). The risk estimates differed with lags and the use of different heatwave definitions. There was a significant increase in EHAs for renal diseases in children during heatwaves in Brisbane, a subtropical city where people are well accustomed to warm weather. This finding may have significant implications for pediatric renal care, particularly in subtropical and tropical regions.

Experimental research on physiological response of elderly with cardiovascular disease during heat wave period

The fact that the environment and human beings interact with each other has been known for centuries. In the present study, elderly’s heart rate (HR) and blood pressure response to indoor thermal comfort and indoor air quality (IAQ) were investigated. Indoor thermal comfort was characterized by Humidex, IAQ by CO2 concentrations. The results show that HR increase which is a prognostic factor for cardiovascular mortality is related to an increase of heat burden and low air quality. Meanwhile blood pressure would decrease as physiological response to these conditions. Our study demonstrates that common impact of heat burden and poor air quality on blood pressure and HR is greater than impact of exposure to each of them. Planners and decision makers that work in the field of designing indoor environment for elderly people or other risk groups should be aware of interactive influence of the thermal environment and the air quality on health and that unsuitability conditions could be ascertained by the occupants’ physiological response.

The effect of dwelling occupants on energy consumption: the case of heat waves in Australia

Climate change predictions indicate more extremes in weather conditions in the coming decades with more frequent and severe heat waves in certain locations including Australia. It is likely that the more vulnerable members of the community will be at risk during heat waves in the future from both health and financial perspectives. The trend towards fully air conditioned larger homes has already seen very large peaks in electricity demand during past heat waves. Electricity prices have increased substantially in recent years and will increase further due to greater peak demand and environmental levies. To manage the risks to dwelling occupants during heat waves, research has been carried out to determine methods of promoting adaptive behaviours through residential design. This paper describes the concept of a “cool retreat” within a dwelling which can provide comfort conditions with minimal cooling costs during heat wave periods. The cool retreat concept is shown to have its origins in the past in a number of locations around the world subject to hot conditions. Various cool retreat configurations have been analysed for thermal performance, demonstrating the viability of this approach for dealing with extreme conditions in the future.

The Impact of Heat Waves on Transport Volumes in an Urban Emergency Medical Services System: A Retrospective Review

Heat waves pose a serious public health risk to particular patient populations, especially in urban areas. Emergency Medical Services (EMS) in many urban areas constitute the first line of regional preparation and response to major heat wave events; however, little is known on heat wave operational impact to the EMS system, such as call volume or demand. To examine the effect of heat wave periods on overall urban EMS system call volume and transport volume as well as the nature of the call types. Retrospective review of all emergency medical calls to an urban, two-tiered EMS system performed over a 5-year period from 2006-2010. Heat wave days (HWD) defined as two or more consecutive days of hot weather >32.2°C (90°F) were compared with similar non-heat wave days (nHWD) of the previous year to also include two calendar days prior to and after the heat wave. National Weather Service (NWS) temperature data, daily EMS call volume data, and call type codes were collected and underwent descriptive analysis. Thirty-one HWD were identified and compared with 93 nHWD. The mean maximum temperature for HWD was 34°C (93.2°F) compared with 25.3°C (77.6°F) for nHWD (P < .001). Average daily medical emergency calls (318.4 vs 296.3, P < .001) and actual patients transported per day (247.5 vs 198.3, P < .001) were significantly higher during HWD. There was no difference in daily medical emergency call volume or EMS transports between weekdays or weekend days. No significant differences on various call types were observed between HWD and nHWD except for "heat" related calls (7.7 vs 0.5, P < .001). Emergency Medical Services call volumes were significantly increased during heat waves, however there was minimal change in the types of calls received.

Associations between risk perception, spontaneous adaptation behavior to heat waves and heatstroke in Guangdong province, China

BackgroundIn many parts of the world, including in China, extreme heat events or heat waves are likely to increase in intensity, frequency, and duration in light of climate change in the next decades. Risk perception and adaptation behaviors are two important components in reducing the health impacts of heat waves, but little is known about their relationships in China. This study aimed to examine the associations between risk perception to heat waves, adaptation behaviors, and heatstroke among the public in Guangdong province, China.MethodsA total of 2,183 adult participants were selected using a four-stage sampling method in Guangdong province. From September to November of 2010 each subject was interviewed at home by a well-trained investigator using a structured questionnaire. The information collected included socio-demographic characteristics, risk perception and spontaneous adaptation behaviors during heat wave periods, and heatstroke experience in the last year. Chi-square tests and unconditional logistic regression models were employed to analyze the data.ResultsThis study found that 14.8%, 65.3% and 19.9% of participants perceived heat waves as a low, moderate or high health risk, respectively. About 99.1% participants employed at least one spontaneous adaptation behavior, and 26.2%, 51.2% and 22.6% respondents employed <4, 4–7, and >7 adaptation behaviors during heat waves, respectively. Individuals with moderate (OR=2.93, 95% CI: 1.38-6.22) or high (OR=10.58, 95% CI: 4.74-23.63) risk perception experienced more heatstroke in the past year than others. Drinking more water and wearing light clothes in urban areas, while decreasing activity as well as wearing light clothes in rural areas were negatively associated with heatstroke. Individuals with high risk perception and employing <4 adaptation behaviors during heat waves had the highest risks of heatstroke (OR=47.46, 95% CI: 12.82-175.73).ConclusionsThere is a large room for improving health risk perception and adaptation capacity to heat waves among the public of Guangdong province. People with higher risk perception and fewer adaptation behaviors during heat waves may be more vulnerable to heat waves.

Heat Waves, Incidence of Infectious Gastroenteritis, and Relapse Rates of Inflammatory Bowel Disease: A Retrospective Controlled Observational Study

The objective of this study was to evaluate the effect of heat waves on flares of inflammatory bowel disease (IBD) and infectious gastroenteritis (IG). In this retrospective controlled observational study, data from 738 IBD and 786 IG patients admitted to the University Hospital of Zurich in the years 2001-2005, as well as from 506 other noninfectious chronic intestinal inflammations, which were used as control, were collected. Climate data were obtained from the Swiss Federal Office for Meteorology and Climatology. The presence of a heat wave increased the risk of IBD flares by 4.6% (95% confidence interval (CI): 1.6-7.4%, P=0.0035) and of IG flares by 4.7% (95% CI: 1.8-7.4%, P=0.0020) for every additional day within a heat wave period. In the control group there was no significant effect (95% CI: -6.2-2.9%, P=0.53). Screening of alternative forms for the effect of heat waves suggested that for IG the effect is strongest when lagged by 7 days (risk increase per day: 7.2%, 95% CI: 4.6-9.7%, P<0.0001), whereas for IBD no such transformation was required. Other formulations with additive effects, interactions between heat waves and time of the year, and additional adjustments for daily average temperature did not show any improvement in model fit. In this retrospective controlled observational study, we found a substantial increase in hospital admissions because of flares of IBD and IG during heat wave periods. Whereas the effect on IG is strongest with a delay of 7 days, the effect on IBD flares is immediate, suggesting different mechanisms.

The Impact of Heat Waves on Mortality in Nanjing Area from 2004 to 2010

This paper analyzed the excess mortality change in nine districts of Nanjing city, based on mortality data and meteorological data from 2004 to 2010. Taken a typical heat waves process in summer of 2006 as an example, it was discussed of the effect of the heat process on different gender, different age groups , and various disease death toll and excess mortality changes. The excess mortality was associated with the average maximum temperature and average minimum temperature during the heat waves. Excess mortality occurred in the middle of June heat wave when excess mortality was much higher than in other time periods. In late June, early July to early August, the excess mortality is relatively small. The average daily deaths are increasing with increasing age for male and female, and every age death numbers is higher than that with no heat waves during the heat wave period. In addition to the respiratory system diseases, diseases of the genitourinary system, other diseases, residual disease in the heat waves has increased, and diseases of the nervous system and the endocrine system diseases of excess mortality rate reached a staggering 342.93% and 119.63%, accounting for almost half of the total heat excess mortality. The heat waves effect is very obvious. The conclusion is of great significance for prevention of high temperature heat harm.

Analysis of Heat Illness using Michigan Emergency Department Syndromic Surveillance

During a severe heat wave in Michigan in 2012, heat-related Emergency Department cases were identified using the Michigan Emergency Department (ED) Syndromic Surveillance System. Heat-related ED visits were analyzed by patient age, gender, and chief complaint. These ad hoc enhanced analyses were performed by Michigan Department of Community Health epidemiologists and provided to public health partners for situational awareness and to guide their responses to the heat event. Significant differences in the patterns of heat-related illnesses were observed during the heat-wave period compared to a reference period.

Risk factors for direct heat-related hospitalization during the 2009 Adelaide heatwave: A case crossover study

Adelaide experienced an extreme and prolonged 13days heatwave in summer 2009. The health impacts of this heatwave included an almost 14-fold increase in direct heat-related hospital admissions. This study aims to investigate the risk factors for this extra health burden. A case crossover study was conducted in metropolitan Adelaide to compare the characteristics of patients from the heatwave (exposure) period and non-heatwave (control) periods before and after. Direct heat-related hospitalizations were identified based on the ICD-10 codes (X30, T67, and E86). Patients' data, including age, gender, indicators of health status, living conditions and socio-economic status, were collected from the South Australian Department of Health and patients' case-notes from seven major Adelaide hospitals. Multivariate logistic regression model was used to estimate the odd ratios (OR) and the 95% confidence intervals (CI). Results indicate that living at residential aged care (OR=0.41, 95% CI: 0.15–0.70) and having higher number of co-morbidities (OR=0.89, 95% CI: 0.83–0.95) reduced the risk of hospital admission for direct heat-related illnesses during the heatwave, while having renal problems (OR=1.72, 95% CI: 1.07–2.94), reporting a fall prior to hospitalization (OR=2.04, 95% CI: 1.10–3.77), receiving assistance from community (OR=2.31, 95% CI: 1.24–4.30), living alone (OR=2.41, 95% CI: 1.32–4.40), socio-economic disadvantage (OR=2.10, 95% CI: 1.09–4.04) and no private health insurance (OR=1.82, 95% CI: 1.05–3.16) increased the risk. In conclusion, the people most at risk during the 2009 heatwave in Adelaide were those who lived alone, received help from community services, with co-existing renal problems or a risk of falls, and with a lower socio-economic status. Findings will assist in refining heat-health response systems and developing intervention programmes.

Mapping Heat Health Risks in Urban Areas

Periods of extreme heat pose a risk to the health of individuals, especially the elderly, the very young, and the chronically ill. Risk factors include housing characteristics, and socioeconomic factors, or environmental risk factors such as urban heat islands. This study developed an index of population vulnerability in an urban setting using known environmental, demographic, and health-related risk factors for heat stress. The spatial variations in risk factors were correlated with spatial variation in heat-related health outcomes in urban Melbourne. The index was weighted using measured health outcomes during heatwave periods. The index was then mapped to produce a spatial representation of risk. The key risk factors were identified as areas with aged care facilities, higher proportions of older people living alone, living in suburban rather than inner city areas, and areas with larger proportions of people who spoke a language other than English at home. The maps of spatial vulnerability provide information to target heat-related health risks by aiding policy advisors, urban planners, healthcare professionals, and ancillary services to develop heatwave preparedness plans at a local scale.

Increased Mortality During the 2010 Heat Wave in Harbin, China

In this study, we investigated the effect on daily mortality of a 2010 heat wave in the city of Harbin in northern China. We calculated mortality rate ratios (RRs) by comparing the number of deaths during the heat wave period (June 7th-11th, 2010) to the number of deaths in the reference period (June 8th-12th, 2009). During the heat wave period, an overall excess of 41% in total mortality occurred in Harbin. The RR of total mortality was 1.41 (95% CI 1.22-1.63). Analysis by categories also found dramatic increases in the number of deaths in different gender, age groups and places of death. The 2010 heat wave was a strong risk factor for mortality in Harbin. Public health efforts should be improved to address the potential adverse health effects of heat waves.

A case-crossover study on the association between heat waves and daily deaths caused by acute myocardial infarction

To explore the effects of heat wave on daily deaths caused by acute myocardial infarction (AMI) in Beijing. A case-crossover design was used to study the impact of 5 heat waves on the daily number of AMI deaths from Jan. 1, 1999 to Jun. 30, 2000. The effect of heat wave on death in different gender or age groups was also compared. The 7th day before and after death occurred was chosen as its own bi-directional self-control. The OR value and its corresponding risk period was used to reflect the impact of heat wave on daily number of AMI deaths, lag days and duration. There were five heat waves during the study period. The first heat wave sustained 9 days and the maximum temperature was 38.8°C with average humidity as 46.7%. The OR value for the AMI death was 1.437 (95%CI: 1.066 - 1.937). The second heat wave lasted 3 days, with the maximum temperature of 36.8°C and average humidity of 61.0%. The OR value for the AMI death was 1.846 (95%CI: 0.671 - 5.076). The third heat wave continued 7 days, with the maximum temperature of 41.5°C with average humidity of 58.5%. The OR value for the daily death counts caused by AMI was 2.427 (95%CI: 1.825 - 3.229). The fourth lasted for 3 days, with the maximum temperature of 39.6°C and average humidity as 31.9%. The OR value for the AMI deaths was 2.857 (95%CI: 1.088 - 7.506). The fifth heat wave lasted for 4 days, with the maximum temperature as 37.4°C, and average humidity as 42.0% during this period. The OR value for daily death counts caused by AMI was 1.500 (95%CI: 0.632 - 3.560). The OR value of the first heat wave for daily death counts of men and women caused by AMI were 1.153 (95%CI: 0.756 - 1.758) and 1.818 (95%CI: 1.185 - 2.790) respectively. The OR value for daily death counts of under 65 age was 1.200 (95%CI: 0.669 - 2.153), with the OR value for the older than 64 age group was 1.534 (95%CI: 1.083 - 2.173). The OR value for daily death counts of older than 64 age women was 1.818 (95%CI: 1.109 - 2.981). The OR values of the third heat wave for daily death counts of men and women caused by AMI were 2.392 (95%CI: 1.649 - 3.470) and 2.514 (95%CI: 1.613 - 3.919) respectively. The OR value for daily death counts of under 65 age group was 2.000 (95%CI: 1.149-3.482) and the OR value for the older than 64 age group was 2.623 (95%CI: 1.880 - 3.660). The OR value for daily death counts of older than 64 age group women was 2.800 (95%CI: 1.676 - 4.678). (1) Significant increase for daily death counts of AMI in Beijing was noticed during the heat wave and usually causing hysteretic effect. The lag phase was 0 - 2 days in general. (2) The increase of maximum temperature was greater at the beginning day when the heat wave occurred in the previous day, with shorter lag time and greater risk of AMI death. (3) The risk of AMI death in women was greater than in men during the heat wave period. (4) The risk of AMI death among those older than 64 age group was greater than the under 65 year olds. (5) The impact of heat wave to the elderly female was greater.

Heat Waves and Cause-specific Mortality at all Ages

Mortality has been shown to increase with extremely hot ambient temperatures. Details on the specific cause of mortality can be useful for improving preventive policies. Infants are often identified as a population that is vulnerable to extreme heat conditions; however, information on heat and infant mortality is scarce, with no studies reporting on cause-specific mortality. The study includes all deaths in the Catalonia region of Spain during the warm seasons of 1983-2006 (503,389 deaths). We used the case-crossover design to evaluate the association between the occurrence of extremely hot days (days with maximum temperature above the 95th percentile) and mortality. Total mortality and infant mortality were stratified into 66 and 8 causes of death, respectively. Three consecutive hot days increased total daily mortality by 19%. We calculated that 1.6% of all deaths were attributable to heat. About 40% of attributable deaths did not occur during heat-wave periods. The causes of death that were increased included cardiovascular and respiratory diseases, mental and nervous system disorders, infectious and digestive system diseases, diabetes, and some external causes such as suicide. In infants, the effect of heat was observed on the same day and was detected only for conditions originating in the perinatal period (relative risk = 1.53 [95% confidence interval = 1.16-2.02]). Within the perinatal causes, cardiovascular, respiratory, digestive system, and hemorrhagic and hematologic disorders were the causes of death with stronger effects. Heat contributes to an increase in mortality from several causes. In infants, the first week of life is the most critical window of vulnerability.