Rural–urban differences in the prevalence of cognitive impairment in independent community-dwelling elderly residents of Ojiya city,Niigata Prefecture,Japan

Background

This study aimed to examine rural–urban differences in the prevalence of cognitive impairment in Japan.

Methods

We targeted 592 residents aged 65 years and older who did not use long-term care insurance services in one rural and two urban areas in Ojiya City, Japan. Of these, 537 (90.7 %) participated in the study. The revised Hasegawa’s dementia scale (HDS-R) was used to assess cognitive function, and cognitive impairment was defined as a HDS-R score ≤20. Lifestyle information was obtained through interviews. The prevalence of cognitive impairment was compared according to the levels of predictor variables by odds ratios (ORs) calculated by a logistic regression analysis.

Results

Mean age of participants was 75.7 years (SD 7.0). The prevalence of cognitive impairment was 20/239 (8.4 %) in the rural area and 6/298 (2.0 %) in the urban areas, for a total of 26/537 (4.8 %) overall. Men tended to have a higher prevalence of cognitive impairment (P = 0.0628), and age was associated with cognitive impairment (P for trend <0.0001). The rural area had a significantly higher prevalence of cognitive impairment (age- and sex-adjusted OR = 4.04, 95 % CI: 1.54–10.62) than urban areas. This difference was significant after adjusting for other lifestyle factors.

Conclusions

The prevalence of cognitive impairment was higher in the rural area relative to urban areas in Ojiya city. This regional difference suggests the existence of potentially modifiable factors other than lifestyle in relation to cognitive impairment.

     

Urban Area Disadvantage and Under-5 Mortality in Nigeria: The Effect of Rapid Urbanization

Background

Living in socioeconomically disadvantaged areas is associated with increased childhood mortality risks. As city living becomes the predominant social context in low- and middle-income countries, the resulting rapid urbanization together with the poor economic circumstances of these countries greatly increases the risks of mortality for children < 5 years of age (under-5 mortality).

Objective

In this study we examined the trends in urban population growth and urban under-5 mortality between 1983 and 2003 in Nigeria. We assessed whether urban area socioeconomic disadvantage has an impact on under-5 mortality.

Methods

Urban under-5 mortality rates were directly estimated from the 1990, 1999, and 2003 Nigeria Demographic and Health Surveys. Multilevel logistic regression analysis was performed on data for 2,118 children nested within data for 1,350 mothers, who were in turn nested within data for 165 communities.

Results

Urban under-5 mortality increased as urban population steadily increased between 1983 and 2003. Urban area disadvantage was significantly associated with under-5 mortality after adjusting for individual child- and mother-level demographic and socioeconomic characteristics.

Conclusions

Significant relative risks of under-5 deaths at both individual and community levels underscore the need for interventions tailored toward community- and individual-level interventions. We stress the need for further studies on community-level determinants of under-5 mortality in disadvantaged urban areas.     

Blood lead,cadmium and mercury among children from urban,industrial and rural areas of Fez Boulemane Region (Morocco): Relevant factors and early renal effects

Objectives

To describe blood lead (Pb-B), cadmium (Cd-B) and mercury (Hg-B) levels in children living in urban, industrial and rural areas in Fez city (north of Morocco) and to identify the determinants and some renal effects of exposure.

Material and Methods

The study was conducted from June 2007 to January 2008 in 209 school children (113 girls, 96 boys), aged 6–12 years, from urban, industrial and rural areas in Fez city. Interview and questionnaires data were obtained. Blood and urinary samples were analyzed.

Results

The mean of blood lead levels (Pb-B) in our population was 55.53 μg/l (range: 7.5–231.1 μg/l). Children from the urban area had higher blood lead levels (BLLs) mean (82.36 μg/l) than children from industrial and rural areas (48.23 and 35.99 μg/l, respectively); with no significant difference between boys and girls. BLLs were associated with traffic intensity, passive smoking and infancy in the urban area. The mean of blood cadmium levels (BCLs) was 0.22 μg/l (range: 0.06–0.68 μg/l), with no difference between various areas. Rural boys had higher BCLs mean than rural girls, but no gender influence was noticed in the other areas. BCLs were associated with the number of cigarettes smoked at children’s homes. The blood mercury levels (BMLs) mean was 0.49 μg/l (range: 0.01–5.31 μg/l). The BMLs mean was higher in urban and industrial areas than in the rural area with no gender-related difference. BMLs were associated with amalgam fillings and infancy in the urban area. About 8% of the children had BLLs ≥ 100 μg/l particularly in the urban area, microalbuminuria and a decrease in height were noticed in girls from the inner city of Fez and that can be related to high BLLs (89.45 μg/l).

Conclusions

There is a need to control and regulate potential sources of contamination by these trace elements in children; particularly for lead.     

The family as a determinant of stunting in children living in conditions of extreme poverty: a case-control study

Background

Malnutrition in children can be a consequence of unfavourable socioeconomic conditions. However, some families maintain adequate nutritional status in their children despite living in poverty. The aim of this study was to ascertain whether family-related factors are determinants of stunting in young Mexican children living in extreme poverty, and whether these factors differ between rural or urban contexts.

Methods

A case-control study was conducted in one rural and one urban extreme poverty level areas in Mexico. Cases comprised stunted children aged between 6 and 23 months. Controls were well-nourished children. Independent variables were defined in five dimensions: family characteristics; family income; household allocation of resources and family organisation; social networks; and child health care. Information was collected from 108 cases and 139 controls in the rural area and from 198 cases and 211 controls in the urban area. Statistical analysis was carried out separately for each area; unconditional multiple logistic regression analyses were performed to obtain the best explanatory model for stunting.

Results

In the rural area, a greater risk of stunting was associated with father's occupation as farmer and the presence of family networks for child care. The greatest protective effect was found in children cared for exclusively by their mothers. In the urban area, risk factors for stunting were father with unstable job, presence of small social networks, low rate of attendance to the Well Child Program activities, breast-feeding longer than six months, and two variables within the family characteristics dimension (longer duration of parents' union and migration from rural to urban area).

Conclusions

This study suggests the influence of the family on the nutritional status of children under two years of age living in extreme poverty areas. Factors associated with stunting were different in rural and urban communities.Therefore, developing and implementing health programs to tackle malnutrition should take into account such differences that are consequence of the social, economic, and cultural contexts in which the family lives.

     

Projected impact of urbanization on cardiovascular disease in china

Objectives

The Coronary Heart Disease (CHD) Policy Model-China, a national scale cardiovascular disease computer simulation model, was used to project future impact of urbanization.

Methods

Populations and cardiovascular disease incidence rates were stratified into four submodels: North-Urban, South-Urban, North-Rural, and South-Rural. 2010 was the base year, and high and low urbanization rate scenarios were used to project 2030 populations.

Results

Rural-to-urban migration, population growth, and aging were projected to more than double cardiovascular disease events in urban areas and increase events by 27.0–45.6?% in rural areas. Urbanization is estimated to raise age-standardized coronary heart disease incidence by 73–81 per 100,000 and stroke incidence only slightly.

Conclusions

Rural-to-urban migration will likely be a major demographic driver of the cardiovascular disease epidemic in China.     

„Primary Health Care“ und Urbanisierung

Background

The world of the twenty-first century will be a predominantly urban world. By the year 2008, for the first time in human history, more people were residing in cities than in rural areas. The process of urbanization was mostly completed in the industrialized countries by the mid-twentieth century. In developing countries, however, both number and proportion of city dwellers are increasing.

Methods

To review the process of urbanization in developing countries, its relevance for the social and health situation of urban populations and the consequences arising thereof for the concept of Primary Health Care (PHC).

Results

A rapid urbanization poses great challenges to city councils, e. g. concerning infrastructure and distribution of societal wealth. Today, the process of urbanization is accompanied by a lack of jobs in the formal sector and a change in lifestyle which is not conducive to health, e.g. high calorie and fatty foods. A disaggregation of the health situation shows strong intra-city differentials between wealthy neighbourhoods and slum areas. Slum dwellers remain exposed to communicable diseases and are in addition at risk for non-communicable, chronic diseases. Many of the most prevalent health problems have social causes. Such health problems will persist as long as their social causes are not mended. Evidence-based interventions for tackling social causes of illness are lacking, however.

Discussion

Urbanization poses new challenges to PHC. The present strategies, e.g. prevention, are often restricted to health symptoms and reach the middle classes rather than the urban poor. Instead, strategies directed towards a more human urbanization are required. They would have to make full use of the primary health care approach.     

Subjective symptoms, sleeping problems, and cognitive performance in subjects living near mobile phone base stations

Background

The erection of mobile telephone base stations in inhabited areas has raised concerns about possible health effects caused by emitted microwaves.

Methods

In a cross‐sectional study of randomly selected inhabitants living in urban and rural areas for more than one year near to 10 selected base stations, 365 subjects were investigated. Several cognitive tests were performed, and wellbeing and sleep quality were assessed. Field strength of high‐frequency electromagnetic fields (HF‐EMF) was measured in the bedrooms of 336 households.

Results

Total HF‐EMF and exposure related to mobile telecommunication were far below recommended levels (max. 4.1 mW/m²). Distance from antennae was 24–600 m in the rural area and 20–250 m in the urban area. Average power density was slightly higher in the rural area (0.05 mW/m²) than in the urban area (0.02 mW/m²). Despite the influence of confounding variables, including fear of adverse effects from exposure to HF‐EMF from the base station, there was a significant relation of some symptoms to measured power density; this was highest for headaches. Perceptual speed increased, while accuracy decreased insignificantly with increasing exposure levels. There was no significant effect on sleep quality.

Conclusion

Despite very low exposure to HF‐EMF, effects on wellbeing and performance cannot be ruled out, as shown by recently obtained experimental results; however, mechanisms of action at these low levels are unknown.     

Evaluation of the Quality of Life in Adult Cancer Survivors (QLACS) scale for long-term cancer survivors in a sample of breast cancer survivors

Background

The objective was to study whether a Kiswahili version of the OIDP (Oral Impacts on Daily Performance) inventory was valid and reliable for use in a population of older adults in urban and rural areas of Tanzania; and to assess the area specific prevalence, intensity and perceived causes of OIDP.

Method

A cross-sectional survey was conducted in Pwani region and in Dar es Salaam in 2004/2005. A two-stage stratified cluster sample design was utilized. Information became available for 511 urban and 520 rural subjects (mean age 62.9 years) who were interviewed and participated in a full mouth clinical examination in their own homes.

Results

The Kiswahili version of the weighted OIDP inventory preserved the overall concept of the original English version. Cronbach's alpha was 0.83 and 0.90 in urban and rural areas, respectively, and the OIDP inventory varied systematically in the expected direction with self-reported oral health measures. The respective prevalence of oral impacts was 51.2% and 62.1% in urban and rural areas. Problems with eating was the performance reported most frequently (42.5% in urban, 55.1% in rural) followed by cleaning teeth (18.2% in urban, 30.6% in rural). More than half of the urban and rural residents with impacts had very little, little and moderate impact intensity. The most frequently reported causes of impacts were toothache and loose teeth.

Conclusion

The Kiswahili OIDP inventory had acceptable psychometric properties among non-institutionalized adults 50 years and above in Tanzania. The impacts affecting their performances were relatively common but not very severe.     

Urban tree leaves’ chlorophyll-<Emphasis Type="Italic">a</Emphasis> content as a proxy of urbanization

We tested the effect of urbanization on air pollution based on the chlorophyll-a content of Celtis occidentalis leaves along an urbanization gradient (urban, suburban and rural areas) in Debrecen, Hungary. Chlorophyll-a content of Celtis occidentalis, Acer campestre, and Corylus avellana were compared to test which species is the most useful to study the effects of urbanization. Furthermore, the effects of washing solutions (distilled water, tap water, and rainwater) on chlorophyll-a content of tree leaves were also tested during sample preparation. Chlorophyll-a was extracted from leaf samples with acetone, and it was measured using a spectrophotometer. Along the urbanization gradient, chlorophyll-a content of C. occidentalis leaves was the lowest in the urban area; thus, this species proved to be an effective indicator of anthropogenic emission load. Differences were not significant among species in the suburban and rural areas, where the level of air pollution was moderate. We found that effects of the washing solutions on chlorophyll-a content did not differ significantly from each other. Thus, tap water can be used safely to clean the leaf surface, without significant influence on chlorophyll-a. Our study demonstrated that the chlorophyll-a content of leaves was a useful indicator to assess the level of air pollution.     

Consumo de riesgo de alcohol y factores asociados en adolescentes de 15 a 16 años de la Cataluña Central: diferencias entre ámbito rural y urbano

Objective

To determine the prevalence of risky alcohol consumption and associated risk factors among adolescents living in Central Catalonia (Spain) during the 2011-2012 academic year, depending on their area of residence.

Method

A cross-sectional study was carried out in a sample of 1268 10th grade students (4 th grade of secondary education) in Central Catalonia.

Results

Risky alcohol consumption was higher among adolescents in rural areas than in urban areas (59.6% versus 49.8%). Associated risk factors were drunkenness in siblings and friends, having positive expectations of alcohol consumption, and buying alcohol. Not living with both parents and poorer academic achievement were associated risk factors in rural areas, while higher socioeconomic status was a risk factor in urban areas.

Conclusions

Risky alcohol consumption was much higher among adolescents living in rural areas. The main associated factor was alcohol consumption among family and friends.     

Urban–rural inequalities in suicide mortality: a comparison of urbanicity indicators

Background

Urban–rural disparities in suicide mortality have received considerable attention. Varying conceptualizations of urbanity may contribute to the conflicting findings. This ecological study on Germany assessed how and to what extent urban–rural suicide associations are affected by 14 different urban–rural indicators.

Methods

Indicators were based on continuous or k-means classified population data, land-use data, planning typologies, or represented population-based accessibility indicators. Agreements between indicators were tested with correlation analyses. Spatial Bayesian Poisson regressions were estimated to examine urban–rural suicide associations while adjusting for risk and protective factors.

Results

Urban–rural differences in suicide rates per 100,000 persons were found irrespective of the indicator. Strong and significant correlation was observed between different urban–rural indicators. Although the effect sign consistently referred to a reduced risk in urban areas, statistical significance was not universally confirmed by all regressions. Goodness-of-fit statistics suggested that the population potential score performs best, and that population density is the second best indicator of urbanicity. Numerical indicators are favored over classified ones. Regional planning typologies are not supported.

Conclusions

The strength of suicide urban–rural associations varies with respect to the applied indicator of urbanicity. Future studies that put urban–rural inequalities central are recommended to apply either unclassified population potentials or population density indicators, but sensitivity analyses are advised.

     

Worrying exposure to trace elements in the population of Kinshasa, Democratic Republic of Congo (DRC)

Background and objectives

The particularly high rate of urbanization in Kinshasa (Democratic Republic of Congo) is associated with environmental degradation. Outdoor and indoor air pollution, as well as water pollution and waste accumulation, are issues of major concern. However, little documented information exists on the nature and extent of this pollution. A biomonitoring study was conducted to document exposure to trace elements in a representative sample of the population in Kinshasa.

Methods

Fifteen trace elements were measured by ICP-MS, CV-AAS, or HG-AFS in spot urine samples from 220 individuals (50.5% women) aged 6–70?years living in the urban area and from 50 additional subjects from the rural area of Kinshasa. Data were compiled as geometric means and selected percentiles, expressed without (μg/L) or with creatinine adjustment (μg/g cr).

Results

Overall, living in urban Kinshasa was associated with elevated levels of several parameters in urine as compared to the population living in the rural area (Asi, Ba, Cd, Cr, and V) as well as compared to an urban population of the southeast of Congo (Al, As, Cd, Cr, Cu, Pb, Mn, Ni, Se, V, and Zn). Elevated levels were also found by comparison with the reference values in databases involving American, Canadian, French, or German populations.

Conclusions

This study provides the first biomonitoring database in the population of Kinshasa, revealing elevated levels for most urinary TE as compared to other databases. Toxicologically relevant elements such as Al, As, Cd, Pb, and Hg reach levels of public health concern.     

Rural-urban differentials in pregnancy-related mortality in Zambia: estimates using data collected in a census

Background

The use of census data to measure maternal mortality is a recent phenomenon, implemented in settings with non-functional vital registration systems and driven by needs for trend data. The 2010 round of population and housing censuses recorded a significant increase in the number of countries collecting maternal mortality data. The objective of this study was to estimate rural-urban differentials in pregnancy-related mortality in Zambia using census data.

Methods

We used data from the Zambia 2000 and 2010 censuses. Both censuses recorded the female population by age, the number of children ever born, and live births 12 months prior to the census. The 2010 census further recorded, by age, household, and pregnancy-related deaths 12 months prior to the census. We evaluated and adjusted recorded live births using the cohort Parity Fertility ratio method, and household deaths using deaths distribution methods (General Growth Balance and Synthetic Extinct Generation). Adult female mortality and pregnancy-related mortality for rural and urban areas were estimated for the period October 2009 to October 2010.

Results

Data evaluation showed errors in recorded population age, age-at-death, live births, and deaths, and appropriate adjustments were made. Adjusted adult female mortality was high; an adolescent aged 15 years had a one-in-three chance of dying before her 50th birthday in rural areas and one-in-four chance in urban areas. Pregnancy-related deaths comprised 15.3 % of all deaths among reproductive-age women overall; 17.9 % in rural areas and 9.8 % in urban areas. The pregnancy-related mortality ratio for the period was 789 deaths/100,000 live births overall: 960/100,000 live births in rural areas and 470/100,000 live births in urban areas.

Conclusions

Census-based estimates show very high adult female mortality and particularly high pregnancy-related mortality in both rural and urban areas of Zambia 12 months prior to the 2010 census. Future censuses should pay greater attention to strategies for improving data quality.

     

Economic burden,impoverishment and coping mechanisms associated with out-of-pocket health expenditure: analysis of rural-urban differentials in India

Aim

This article aimed to study the burden, impact and coping mechanisms associated with out-of-pocket (OOP) health expenditure in rural and urban areas in India.

Methods

National Sample Survey Organisation (NSSO) data on ‘Health and Morbidity’ gathered in 2004 and 2014 were employed to measure the catastrophic burden, impoverishment impact and various coping strategies associated with out-of-pocket health in India.

Results

Results revealed that over the study period, considerable rural-urban differentials existed in the economic burden and impact of out-of-pocket health expenditure. As a coping strategy, borrowing and other distress sources were used in higher proportions by the rural population than their urban counterparts. Overall, our results demonstrated an alarming situation regarding health care financing in India.

Conclusion

Substantial investment in public health is needed, especially in rural areas as it is here that people are facing the real brunt of catastrophic OOP health expenditures in the form of impoverishment with more dependence on distress sources including borrowing and sale of assets as coping mechanisms.

     

The geographic distribution of breast cancer incidence in Massachusetts 1988 to 1997, adjusted for covariates

Background

The aims of this study were to determine whether observed geographic variations in breast cancer incidence are random or statistically significant, whether statistically significant excesses are temporary or time-persistent, and whether they can be explained by covariates such as socioeconomic status (SES) or urban/rural status?

Results

A purely spatial analysis found fourteen geographic areas that deviated significantly from randomness: ten with higher incidence rates than expected, four lower than expected. After covariate adjustment, three of the ten high areas remained statistically significant and one new high area emerged. The space-time analysis identified eleven geographic areas as statistically significant, seven high and four low. After covariate adjustment, four of the seven high areas remained statistically significant and a fifth high area also identified in the purely spatial analysis emerged.

Conclusions

These analyses identify geographic areas with invasive breast cancer incidence higher or lower than expected, the times of their excess, and whether or not their status is affected when the model is adjusted for risk factors. These surveillance findings can be a sound starting point for the epidemiologist and has the potential of monitoring time trends for cancer control activities.

     

Unravelling the extent of inequalities in health across urban and rural areas: Evidence from a national sample in England

Studies of inequalities in health between rural and urban settings have produced mixed and sometimes conflicting results, depending on the national setting of the study, the level of geographic detail used to define rural areas and the health indicators studied. By focusing on morbidity data from a national sample of individuals, this study aims to examine the extent of inequalities in health between urban and rural areas, as well as inequalities in health across rural areas of England. Multilevel analyses for poor self-rated health, overweight and obesity, and common mental disorders are reported for a sample of 30,776 individuals aged 18 years and older (obtained from the Health Survey for England years 2000–2003 combined) and distributed across 3645 small areas classed in four categories: two groups of urban areas (Greater London area or ‘other cities’) and two types of rural settings (semi-rural areas or villages). Results show that rural dwellers were significantly less likely than residents of urban areas to report their health as being fair or poor and to report common mental disorders, independent of their socio-demographic characteristics. However, as for urban settlements, there were significant variations in health across semi-rural areas and across villages, indicating the presence of health inequalities within rural settings in England. These inequalities were not fully explained by the individual composition of the areas or by the available measures of area socioeconomic conditions, indicating that in rural contexts more specific factors may have significance for health. Different policies and services for health promotion and care may need to be targeted to different types of rural areas.     

Urban-Rural Differences in Coronary Heart Disease Mortality in the United States: 1999–2009

Objective

Coronary heart disease (CHD) mortality has declined in the past few decades; however, it is unclear whether the reduction in CHD deaths has been similar across urbanization levels and in specific racial groups. We describe the pattern and magnitude of urban-rural variations in CHD mortality in the U.S.

Methods

Using data from the National Center for Health Statistics, we examined trends in death rates from CHD from 1999 to 2009 among people aged 35–84 years, in each geographic region (Northeast, Midwest, West, and South) and in specific racial-urbanization groups, including black and white people in large and medium metropolitan (urban) areas and in non-metropolitan (rural) areas. We also examined deaths from early-onset CHD in females aged <65 years and males aged <55 years.

Results

From 1999 to 2009, there was a 40% decline in age-adjusted CHD mortality. The trend was similar in black and white people but was more pronounced in urban than in rural areas, resulting in a crossover in 2007, when rural areas began showing a higher CHD mortality than urban areas. White people in large metropolitan areas had the largest decline (43%). Throughout the study period, CHD mortality remained higher in black people than in white people, and, in the South, it remained higher in rural than in urban areas. For early-onset CHD, the mortality decline was more modest (30%), but overall trends by urbanization and region were similar.

Conclusion

Favorable national trends in CHD mortality conceal persisting disparities for some regions and population subgroups (e.g., rural areas and black people).Coronary heart disease (CHD) is the leading cause of death for most racial groups in the United States, accounting for approximately 600,000 total deaths annually.¹ CHD remains the leading cause of morbidity and mortality despite the fact that CHD death rates have declined by more than 30% since the 1990s.² This decline has been attributed to a combination of primary and secondary prevention efforts, with a reduction in the level of risk factors, such as blood pressure, smoking, and blood cholesterol, and continuing improvements in diagnosis and treatment.^3–6Although encouraging, the overall decline in CHD mortality rates in the U.S. may conceal less favorable trends in certain regions and demographic groups. Urbanization level is a key characteristic when studying health disparities. One-fifth of the U.S. population resides in rural areas, which rank poorly on 21 of 23 selected population health indicators, behaviors, and risk factors.^7–9 Urban-rural differences provide opportunities for optimizing health-care resources and improving prevention targeting areas of highest need.Few previous studies have described regional differences in CHD mortality in the U.S. and trends over time in recent years.^10–12 There is an ongoing need to monitor the distribution of death rates from specific causes to help reduce preventable diseases and deaths and improve the health of all groups.¹³ This study describes the pattern and magnitude of urban-rural differences in CHD mortality rates by geographic region in the U.S. from 1999 to 2009. The extent to which the decline applies to early CHD mortality is also examined. Deaths from early-onset CHD translate into a large number of years of potential life lost with substantial impact on families and society. Thus, the study of potential determinants of early-onset CHD is important but often neglected.     

Rural and urban differences in the associations between characteristics of the community food environment and fruit and vegetable intake

Objective

To examine the relationship between measures of the household and retail food environments and fruit and vegetable (FV) intake in both urban and rural environmental contexts.

Design

A cross-sectional design was used. Data for FV intake and other characteristics were collected via survey instrument and geocoded to the objective food environment based on a ground-truthed (windshield audit) survey of the retail food environment.

Setting

One urban and 6 contiguous rural counties.

Participants

This study involved 2,556 residents of the Brazos Valley, Texas, who were selected through random-digit dialing.

Main Outcome Measure

Two-item scale of FV intake.

Analysis

Data were analyzed using chi-square analysis, 2-sample t tests, and linear regression.

Results

Distance to supermarket or supercenter was insignificant in the urban model, but significant in the rural model (β = -.014, P < .010, confidence interval = -.024, -.003).

Conclusions and Implications

Retail food environments have different impacts on FV intake in urban and rural settings. Interventions to improve FV intake in these settings should account for the importance of distance to the retail food environment in rural settings.     

Attribution of mortality to the urban heat island during heatwaves in the West Midlands,UK

Background

The Urban Heat Island (UHI) effect describes the phenomenon whereby cities are generally warmer than surrounding rural areas. Traditionally, temperature monitoring sites are placed outside of city centres, which means that point measurements do not always reflect the true air temperature of urban centres, and estimates of health impacts based on such data may under-estimate the impact of heat on public health. Climate change is likely to exacerbate heatwaves in future, but because climate projections do not usually include the UHI, health impacts may be further underestimated. These factors motivate a two-dimensional analysis of population weighted temperature across an urban area, for heat related health impact assessments, since populations are typically densest in urban centres, where ambient temperatures are highest and the UHI is most pronounced. We investigate the sensitivity of health impact estimates to the use of population weighting and the inclusion of urban temperatures in exposure data.

Methods

We quantify the attribution of the UHI to heat related mortality in the West Midlands during the heatwave of August 2003 by comparing health impacts based on two modelled temperature simulations. The first simulation is based on detailed urban land use information and captures the extent of the UHI, whereas in the second simulation, urban land surfaces have been replaced by rural types.

Results and conclusions

The results suggest that the UHI contributed around 50 % of the total heat-related mortality during the 2003 heatwave in the West Midlands. We also find that taking a geographical, rather than population-weighted, mean of temperature across the regions under-estimates the population exposure to temperatures by around 1 °C, roughly equivalent to a 20 % underestimation in mortality. We compare the mortality contribution of the UHI to impacts expected from a range of projected temperatures based on the UKCP09 Climate Projections. For a medium emissions scenario, a typical heatwave in 2080 could be responsible for an increase in mortality of around 3 times the rate in 2003 (278 vs. 90 deaths) when including changes in population, population weighting and the UHI effect in the West Midlands, and assuming no change in population adaptation to heat in future.