Visits to the accident and emergency department in hot season of a city with subtropical climate: association with heat stress and related meteorological variables.

BACKGROUND: Literature reporting the association between heat stress defined by universal thermal climate index (UTCI) and emergency department visits is mainly conducted in Europe. This study aimed to investigate the association between heat stress, as defined by the UTCI, and visits to the accident and emergency department (AED) in Hong Kong, which represents a subtropical climate region. METHODS: A retrospective study involving 13,438,846 AED visits in the public sector from May 2000 to September 2016, excluding 2003 and 2009, was conducted in Hong Kong. Age-sex-specific ANCOVA models of daily AED rates on heat stress and prolonged heat stress, adjusting for air quality, prolonged poor air quality, typhoon, rainstorm, year, day of the week, public holiday, summer vacation, and fee charging, were used. RESULTS: On a day with strong heat stress (32.1 °C ≤ UTCI ≤ 38.0 °C), the AED visit rate (per 100,000) increased by 0.9 (95% CI: 0.5, 1.3) and 1.7 (95% CI: 1.3, 2.1) for females and males aged 19-64 and 4.1 (95% CI: 2.7, 5.4) and 4.1 (95% CI: 2.6, 5.6) for females and males aged ≥ 65, while keeping other variables constant. On a day with very strong heat stress (38.1 °C ≤ UTCI ≤ 46.0 °C), the corresponding rates increased by 0.6 (95% CI: 0.1, 1.2), 2.2 (95% CI: 1.7, 2.7), 4.9 (95% CI: 3.1, 6.7), and 4.7 (95% CI: 2.7, 6.6), respectively. The effect size of heat stress associated with AED visit rates was negligible among those aged ≤ 18. Heat stress showed the greatest effect size for males aged 19-64 among all subgroups. CONCLUSION: Biothermal condition from heat stress was associated with the health of the citizens in a city with a subtropical climate and reflected in the increase of daily AED visit. Public health recommendations have been made accordingly for the prevention of heat-related AED visits.

Longitudinal association of built environment pattern with DXA-derived body fat in elderly Hong Kong Chinese: a latent profile analysis.

BACKGROUND: One major limitation of prior studies regarding the associations between built environment (BE) and obesity has been the use of anthropometric indices (e.g., body mass index [BMI]) for assessing obesity status, and there has been limited evidence of associations between BE and body fat. This study aimed to explore the longitudinal association between BE and body fat in a cohort of elderly Hong Kong Chinese and examine whether the BE-body fat associations differed by BMI categories. METHODS: Between 2001 and 2003, 3944 participants aged 65-98 years were recruited and followed for a mean of 6.4 years. BE characteristics were assessed via Geographic Information System. Body fat (%) at whole body and regional areas (trunk, limbs, android, and gynoid) were assessed by dual energy X-ray absorptiometry at baseline and three follow-ups. Latent profile analysis was used to derive BE class, and linear mixed-effects models were used to investigate the associations of BE class with changes in body fat. Stratified analyses by BMI categories were also conducted. RESULTS: Three BE classes were identified. Participants in Class 2 (characterized by greater open space and proportion of residential land use) had a slower increase in whole body fat (B = -0.403, 95% confidence interval [CI]: -0.780, -0.014) and limbs fat (-0.471, 95% CI: -0.870, -0.071) compared with participants in Class 1 (characterized by high proportion of commercial land use). There were significant interactions of BE class with BMI, and participants in Class 2 had a slower increase in whole body fat and regional fat compared with participants in Class 1 (B ranging from -0.987 [limbs] to -0.523 [gynoid]) among overweight and obese participants only. CONCLUSIONS: We found that those who resided in the areas characterized by greater open space and proportion of residential land use had a slower body fat increase.

Association of urban built environment and socioeconomic factors with suicide mortality in high-density cities: A case study of Hong Kong.

Population ageing, climate change and urbanization have been occurring rapidly globally. Evidence-based healthy city development is required to improve living quality and mitigate the adverse impact of city living on both physical and mental health. We took a high-density city as an example to explore the association of built environment and suicide mortality and preferably to offer some implications for better future city development. Poisson generalized linear models with generalized estimation equations were employed to regress suicide mortality rate on four urban built environment variables (frontal area density (FAD), sky view factor (SVF), ground coverage ratio (GCR), and street coverage ratio (SCR)), as well as socioeconomic factors, population density, and greenery. The association for different causes of death and within different subgroups was also investigated. Generally, higher FAD and GCR were associated with higher suicide mortality while higher SVF and SCR were associated with lower suicide mortality. Age was a significant effect modifier. An interquartile range increase in FAD, SVF, and GCR was associated with 0.81 (95% confidence interval (CI) 0.71-0.92), 1.41 (95% CI 1.04-1.91), and 0.70 (95% CI 0.50-0.98) times the risk of suicide among the people aged over 70, respectively. Higher population density and unmarried status were generally associated with higher suicide rate whereas higher education level was associated with a decreased risk. Unfavorable built environment could increase risks for successful suicide attempts. Better urban development with morphological control mitigating intensifying urban heat island and other micro-environment changes are warranted to promote not only physical but psychological health.

Longitudinal Association of Built Environment Pattern with Physical Activity in a Community-Based Cohort of Elderly Hong Kong Chinese: A Latent Profile Analysis.

A large number of studies have focused on the associations between single built environment (BE) characteristics and physical activity (PA). Combinations of BE characteristics offer a more comprehensive approach to identify the BE-PA associations. We aimed to examine the BE-PA associations in a cohort of elderly Hong Kong Chinese. Between 2001 and 2003, 3944 participants (65-98 years of age) were recruited and followed for a mean of 7.8 years. BE characteristics were assessed via geographic information system. PA levels were obtained using the Physical Activity Scale for the Elderly questionnaire at baseline and three follow-ups. Latent profile analysis was first conducted to classify the BE characteristics, and linear mixed-effects models were then used to explore the longitudinal associations between the BE classes and changes in the PA levels. Three classes of BE were identified. Class 3 (characterized by greater green space and sky view factor) demonstrated a significant decline in household PA (ß = -1.26, 95% confidence interval: -2.20, -0.33) during the study period, and a slower decline in walking PA (1.19 (0.42, 1.95)) compared with Class 2 (characterized by a greater proportion of residential land use). Our results indicate that BE patterns characterized by high green space and a sky view factor may help promote the walking PA level.

Right tree, right place (urban canyon): Tree species selection approach for optimum urban heat mitigation - development and evaluation.

The re-integration of trees into the urban landscape is a veritable strategy for urban climate mitigation and adaptation. However, dysfunctional trees in terms of urban heat mitigation are dominant in many sub-tropical cities' landscapes due to the lack of scientific basis of tree selection. Therefore, this study proposes and evaluates a methodological framework as an approach for "right tree, right place" for urban heat mitigation through parametric ENVI-met simulations that involve the combination of 54 generic tree forms and 10 characteristic urban morphology - Sky-View Factor (SVF). Results show variable temperature regulation by tree forms (species) with varying magnitude in different urban morphology. Daytime and nighttime temperature regulation effects were between 0.3 °C - 1.0 °C and 0.0 °C - 2.0 °C, respectively depending on tree forms and SVF value. Furthermore, the Heat Reduction Potential (HRP) of trees forms were determined in terms of their human thermal comfort improvement. In general, we found a range of +5% and - 20% depending on SVF, negative and positive values imply heat reduction and increment, respectively. With the competing shading effect of buildings, the HRP of trees reduces from high to low SVF area with variable magnitude among tree forms (species). Hence, the proposed morphology-based tree selection approach was evaluated by comparison with two uninformed selection approaches in a realistic urban neighborhood in Hong Kong. Results clearly indicate the proposed approach's capability in improving human thermal comfort by up two times more than either of the other approaches. Finally, evidence-based recommendations were given for the reference of policy-makers when they make urban green development plan.

Designing Urban Green Spaces for Older Adults in Asian Cities.

Elderly populations in Asian countries are expected to increase rapidly in the next few decades. Older adults, particularly in high-density cities, spend a considerable amount of time in urban green spaces (UGSs). The World Health Organization noted that UGSs are key to improving the age-friendliness of neighborhoods. Thus, it is necessary to design UGSs for the promotion of healthy ageing to enhance preventive healthcare and relieve medical burdens. This study conducted interviews using a questionnaire with a sample size of 326 participants in the cities of Hong Kong (China) and Tainan (Taiwan region). The inter-relationships among the design of UGSs (e.g., spatial distribution and accessibility, characteristics of plants and UGSs), older adults' perceptions on safety and aesthetics quality of UGSs, and their self-reported health conditions (assessed by the self-reported SF-12v2 Health Survey) were investigated with bivariate Spearman rank correlation tests. The results indicate that the duration of visits to UGSs was positively associated with mental health and social functioning, two subscales evaluating health-related quality of life in SF 12v2. The statistical model (moderation analysis) showed that such a correlation was especially significant in women and those with low social support and social capital. A positive relationship was found between the physical health subscale and perceived safety in UGSs. This relationship was stronger among older adults living alone (moderation analysis). Furthermore, the color of plants and maintenance condition of UGSs were significant aspects affecting the subjective assessment of aesthetic quality. This study provides useful information regarding how to plan and design urban green spaces with certain characteristics that could improve the accessibility and aesthetic quality, which are preferred by older adults.

The impact of extremely hot weather events on all-cause mortality in a highly urbanized and densely populated subtropical city: A 10-year time-series study (2006-2015).

BACKGROUND: The impact of heatwaves on public health has led to an urgent need to describe extremely hot weather events (EHWEs) and evaluate their health impacts. METHODS: In Hong Kong, a very hot day (VHD) can be defined when the daily maximum temperature ≥ 33 °C, and a hot night (HN) can be identified if the daily minimum temperature ≥ 28 °C. Three lengths of time, nine combinations of VHD and HN, and four categories of occurrence intervals between two EHWEs were considered over 2006-2015. The daily relative risk (RR) of all-cause mortality was estimated using Poisson generalized additive regression models, controlling for both short-term and long-term trends in temperature as well as four air pollutants. Lagged effects of the representative EHWEs were further examined for their association with mortality. Subgroup analysis was conducted for different sex and age groups. RESULTS: Significant associations with raised mortality risks were observed for a single HN, while stronger associations with mortality were observed as significant for five or more consecutive VHDs/HNs. More HNs between the consecutive VHDs also significantly amplified the impact on mortality, with the strongest association observed for EHWEs characterized as 2D3N, and the effect significantly lagged for five days. Therefore, with identifiable health impacts, three thresholds (5VHDs, 5HNs, & 2D3N) were determined to be representative of identical types of EHWEs in Hong Kong. Furthermore, by taking 2 (3) consecutive VHDs (HNs) as one daytime (nighttime) EHWE event, those occurring consecutively without non-hot days (nights) in between were found to be significantly associated with excess mortality risks. Moreover, females and older adults were determined to be relatively more vulnerable to all defined EHWEs. CONCLUSIONS: Among all the observed significant heat-mortality associations in highly urbanized cities, EHWEs that occurred during the nighttime, with extended length, consecutively without any break in between, or in the pattern of 2D3N might require the meteorological administration, healthcare providers, and urban planners to work interactively.

Dynamic response of pedestrian thermal comfort under outdoor transient conditions.

Outdoor thermal comfort studies have proved that urban design has a great influence on pedestrians' thermal comfort and that its assessment helps one to understand the quality and usage of the pedestrian environment. However, the majority of outdoor thermal comfort studies perceive pedestrian thermal comfort as "static". The dynamic multiple uses of urban spaces and the highly inhomogeneous urban morphology in high-density cities of the tropics are seldom considered, which leads to a lack of understanding about how pedestrians respond to the changes of the outdoor environment. This study contributes to the understanding of the dynamic thermal comfort using a longitudinal survey that was conducted to obtain information about how thermal sensation changes throughout the walking route and how it is affected by micro-meteorological conditions and the urban geometry. The large variations in micro-meteorological conditions throughout the walking routes are predominantly influenced by the urban geometry. Additionally, the spatial pattern of thermal sensation varies based on the weather conditions, emphasizing the need to account for such variations in the assessment of pedestrian thermal comfort. The results also show that thermal sensation was associated with participants' short-term thermal experience (2-3 min) and that the urban geometry plays an important role in the time-lag effect of meteorological variables on thermal sensation. The findings of this study contribute to improving urban geometry design in order to mitigate the thermal discomfort and create a better pedestrian environment in high-density cities.

Assessing spatial variability of extreme hot weather conditions in Hong Kong: A land use regression approach.

The number of extreme hot weather events have considerably increased in Hong Kong in the recent decades. The complex urban context of Hong Kong leads to a significant intra-urban spatial variability in climate. Under such circumstance, a spatial understanding of extreme hot weather condition is urgently needed for heat risk prevention and public health actions. In this study, the extreme hot weather events of Hong Kong were quantified and measured using two indicators - very hot day hours (VHDHs) and hot night hours (HNHs) which were counted based on the summertime hourly-resolved air temperature data from a total of 40 weather stations (WSs) from 2011 to 2015. Using the VHDHs and HNHs at the locations of the 40 WSs as the outcome variables, land use regression (LUR) models are developed to achieve a spatial understanding of the extreme hot weather conditions in Hong Kong. Land surface morphology was quantified as the predictor variables in LUR modelling. A total of 167 predictor variables were considered in the model development process based on a stepwise multiple linear regression (MLR). The performance of resultant LUR models was evaluated via cross validation. VHDHs and HNHs were mapped at the community level for Hong Kong. The mapping results illustrate a significant spatial variation in the extreme hot weather conditions of Hong Kong in both the daytime and nighttime, which indicates that the spatial variation of land use configurations must be considered in the risk assessment and corresponding public health management associated with the extreme hot weather.

Effect of long-term acclimatization on summer thermal comfort in outdoor spaces: a comparative study between Melbourne and Hong Kong.

The Universal Thermal Climate Index (UTCI) is an index for assessing outdoor thermal environment which aims to be applicable universally to different climates. However, the scale of UTCI thermal stress classification can be interpreted depending on the context. Previous studies validated the UTCI in individual cities, but comparative studies between different cities are scarce. This study examines the differences in thermal perception and clothing choices between residents from two climate zones over similar UTCI ranges in summer. We compared summer thermal comfort survey data from Melbourne (n = 2162, January-February 2014) and Hong Kong (n = 414, July-August 2007). We calculated the UTCI from outdoor weather station data and used t tests to compare the differences in thermal sensation and clothing between Hong Kong and Melbourne residents. When the UTCI was between 23.0 and 45.9 °C, Melbourne residents wore significantly more clothing (0.1 clo) than Hong Kong residents. Hong Kong residents reported neutral to warm sensation at a higher UTCI range compared with the dynamic thermal sensation (DTS) model. Moreover, Melbourne residents reported warm and hot sensation at a higher UTCI range than the DTS model. Respondents in Melbourne also exhibited different responses to the mean radiant temperature under shaded and sunny conditions, while such a trend was not observed in Hong Kong. It would be advisable to define different thermal sensation thresholds for the UTCI scale according to different climate zones for better prediction of the outdoor thermal comfort of different urban populations.

Spatial Variability of Geriatric Depression Risk in a High-Density City: A Data-Driven Socio-Environmental Vulnerability Mapping Approach.

Previous studies found a relationship between geriatric depression and social deprivation. However, most studies did not include environmental factors in the statistical models, introducing a bias to estimate geriatric depression risk because the urban environment was found to have significant associations with mental health. We developed a cross-sectional study with a binomial logistic regression to examine the geriatric depression risk of a high-density city based on five social vulnerability factors and four environmental measures. We constructed a socio-environmental vulnerability index by including the significant variables to map the geriatric depression risk in Hong Kong, a high-density city characterized by compact urban environment and high-rise buildings. Crude and adjusted odds ratios (ORs) of the variables were significantly different, indicating that both social and environmental variables should be included as confounding factors. For the comprehensive model controlled by all confounding factors, older adults who were of lower education had the highest geriatric depression risks (OR: 1.60 (1.21, 2.12)). Higher percentage of residential area and greater variation in building height within the neighborhood also contributed to geriatric depression risk in Hong Kong, while average building height had negative association with geriatric depression risk. In addition, the socio-environmental vulnerability index showed that higher scores were associated with higher geriatric depression risk at neighborhood scale. The results of mapping and cross-section model suggested that geriatric depression risk was associated with a compact living environment with low socio-economic conditions in historical urban areas in Hong Kong. In conclusion, our study found a significant difference in geriatric depression risk between unadjusted and adjusted models, suggesting the importance of including environmental factors in estimating geriatric depression risk. We also developed a framework to map geriatric depression risk across a city, which can be used for identifying neighborhoods with higher risk for public health surveillance and sustainable urban planning.

Neighbouring green space and mortality in community-dwelling elderly Hong Kong Chinese: a cohort study.

OBJECTIVE: Green space has been shown to be beneficial for human wellness through multiple pathways. This study aimed to explore the contributions of neighbouring green space to cause-specific mortality. METHODS: Data from 3544 Chinese men and women (aged ≥65 years at baseline) in a community-based cohort study were analysed. Outcome measures, identified from the death registry, were death from all-cause, respiratory system disease, circulatory system disease. The quantity of green space (%) within a 300 m radius buffer was calculated for each subject from a map created based on the Normalised Difference Vegetation Index. Cox proportional hazard models adjusted for demographics, socioeconomics, lifestyle, health conditions and housing type were used to estimate the HRs and 95% CIs. RESULTS: During a mean of 10.3 years of follow-up, 795 deaths were identified. Our findings showed that a 10% increase in coverage of green space was significantly associated with a reduction in all-cause mortality (HR 0.963, 95% CI 0.930 to 0.998), circulatory system-caused mortality (HR 0.887, 95% CI 0.817 to 0.963) and stroke-caused mortality (HR 0.661, 95% CI 0.524 to 0.835), independent of age, sex, marital status, years lived in Hong Kong, education level, socioeconomic ladder, smoking, alcohol intake, diet quality, self-rated health and housing type. The inverse associations between coverage of green space with all-cause mortality (HR 0.964, 95% CI 0.931 to 0.999) and circulatory system disease-caused mortality (HR 0.888, 95% CI 0.817 to 0.964) were attenuated when the models were further adjusted for physical activity and cognitive function. The effects of green space on all-cause and circulatory system-caused mortality tended to be stronger in females than in males. CONCLUSION: Higher coverage of green space was associated with reduced risks of all-cause mortality, circulatory system-caused mortality and stroke-caused mortality in Chinese older people living in a highly urbanised city.

Characterizing prolonged heat effects on mortality in a sub-tropical high-density city, Hong Kong.

Extreme hot weather events are likely to increase under future climate change, and it is exacerbated in urban areas due to the complex urban settings. It causes excess mortality due to prolonged exposure to such extreme heat. However, there is lack of universal definition of prolonged heat or heat wave, which leads to inadequacies of associated risk preparedness. Previous studies focused on estimating temperature-mortality relationship based on temperature thresholds for assessing heat-related health risks but only several studies investigated the association between types of prolonged heat and excess mortality. However, most studies focused on one or a few isolated heat waves, which cannot demonstrate typical scenarios that population has experienced. In addition, there are limited studies on the difference between daytime and nighttime temperature, resulting in insufficiency to conclude the effect of prolonged heat. In sub-tropical high-density cities where prolonged heat is common in summer, it is important to obtain a comprehensive understanding of prolonged heat for a complete assessment of heat-related health risks. In this study, six types of prolonged heat were examined by using a time-stratified analysis. We found that more consecutive hot nights contribute to higher mortality risk while the number of consecutive hot days does not have significant association with excess mortality. For a day after five consecutive hot nights, there were 7.99% [7.64%, 8.35%], 7.74% [6.93%, 8.55%], and 8.14% [7.38%, 8.88%] increases in all-cause, cardiovascular, and respiratory mortality, respectively. Non-consecutive hot days or nights are also found to contribute to short-term mortality risk. For a 7-day-period with at least five non-consecutive hot days and nights, there was 15.61% [14.52%, 16.70%] increase in all-cause mortality at lag 0-1, but only -2.00% [-2.83%, -1.17%] at lag 2-3. Differences in the temperature-mortality relationship caused by hot days and hot nights imply the need to categorize prolonged heat for public health surveillance. Findings also contribute to potential improvement to existing heat-health warning system.

Incorporating wind availability into land use regression modelling of air quality in mountainous high-density urban environment.

Urban air quality serves as an important function of the quality of urban life. Land use regression (LUR) modelling of air quality is essential for conducting health impacts assessment but more challenging in mountainous high-density urban scenario due to the complexities of the urban environment. In this study, a total of 21 LUR models are developed for seven kinds of air pollutants (gaseous air pollutants CO, NO2, NOx, O3, SO2 and particulate air pollutants PM2.5, PM10) with reference to three different time periods (summertime, wintertime and annual average of 5-year long-term hourly monitoring data from local air quality monitoring network) in Hong Kong. Under the mountainous high-density urban scenario, we improved the traditional LUR modelling method by incorporating wind availability information into LUR modelling based on surface geomorphometrical analysis. As a result, 269 independent variables were examined to develop the LUR models by using the "ADDRESS" independent variable selection method and stepwise multiple linear regression (MLR). Cross validation has been performed for each resultant model. The results show that wind-related variables are included in most of the resultant models as statistically significant independent variables. Compared with the traditional method, a maximum increase of 20% was achieved in the prediction performance of annual averaged NO2 concentration level by incorporating wind-related variables into LUR model development.

Present and projected future mean radiant temperature for three European cities.

Present-day and projected future changes in mean radiant temperature, T mrt in one northern, one mid-, and one southern European city (represented by Gothenburg, Frankfurt, and Porto), are presented, and the concept of hot spots is adopted. Air temperature, T a , increased in all cities by 2100, but changes in solar radiation due to changes in cloudiness counterbalanced or exacerbated the effects on T mrt. The number of days with high T mrt in Gothenburg was relatively unchanged at the end of the century (+1 day), whereas it more than doubled in Frankfurt and tripled in Porto. The use of street trees to reduce daytime radiant heat load was analyzed using hot spots to identify where trees could be most beneficial. Hot spots, although varying in intensity and frequency, were generally confined to near sunlit southeast-southwest facing walls, in northeast corner of courtyards, and in open spaces in all three cities. By adding trees in these spaces, the radiant heat load can be reduced, especially in spaces with no or few trees. A set of design principles for reducing the radiant heat load is outlined based on these findings and existing literature.

Developing Street-Level PM2.5 and PM10 Land Use Regression Models in High-Density Hong Kong with Urban Morphological Factors.

Monitoring street-level particulates is essential to air quality management but challenging in high-density Hong Kong due to limitations in local monitoring network and the complexities of street environment. By employing vehicle-based mobile measurements, land use regression (LUR) models were developed to estimate the spatial variation of PM2.5 and PM10 in the downtown area of Hong Kong. Sampling runs were conducted along routes measuring a total of 30 km during a selected measurement period of total 14 days. In total, 321 independent variables were examined to develop LUR models by using stepwise regression with PM2.5 and PM10 as dependent variables. Approximately, 10% increases in the model adjusted R(2) were achieved by integrating urban/building morphology as independent variables into the LUR models. Resultant LUR models show that the most decisive factors on street-level air quality in Hong Kong are frontal area index, an urban/building morphological parameter, and road network line density and traffic volume, two parameters of road traffic. The adjusted R(2) of the final LUR models of PM2.5 and PM10 are 0.633 and 0.707, respectively. These results indicate that urban morphology is more decisive to the street-level air quality in high-density cities than other cities. Air pollution hotspots were also identified based on the LUR mapping.

The effect of urban geometry on mean radiant temperature under future climate change: a study of three European cities.

Future anthropogenic climate change is likely to increase the air temperature (T(a)) across Europe and increase the frequency, duration and magnitude of severe heat stress events. Heat stress events are generally associated with clear-sky conditions and high T(a), which give rise to high radiant heat load, i.e. mean radiant temperature (T(mrt)). In urban environments, T mrt is strongly influenced by urban geometry. The present study examines the effect of urban geometry on daytime heat stress in three European cities (Gothenburg in Sweden, Frankfurt in Germany and Porto in Portugal) under present and future climates, using T(mrt) as an indicator of heat stress. It is found that severe heat stress occurs in all three cities. Similar maximum daytime T(mrt) is found in open areas in all three cities despite of the latitudinal differences in average daytime T(mrt). In contrast, dense urban structures like narrow street canyons are able to mitigate heat stress in the summer, without causing substantial changes in T(mrt) in the winter. Although the T(mrt) averages are similar for the north-south and east-west street canyons in each city, the number of hours when T(mrt) exceeds the threshold values of 55.5 and 59.4 °C-used as indicators of moderate and severe heat stress-in the north-south canyons is much higher than that in the east-west canyons. Using statistically downscaled data from a regional climate model, it is found that the study sites were generally warmer in the future scenario, especially Porto, which would further exacerbate heat stress in urban areas. However, a decrease in solar radiation in Gothenburg and Frankfurt reduces T(mrt) in the spring, while the reduction in T(mrt) is somewhat offset by increasing T(a) in other seasons. It suggests that changes in the T(mrt) under the future scenario are dominated by variations in T(a). Nonetheless, the intra-urban differences remain relatively stable in the future. These findings suggest that dense urban structure can reduce daytime heat stress since it reduces the number of hours of high T(mrt) in the summer and does not cause substantial changes in average and minimum T(mrt) in the winter. In dense urban settings, a more diverse urban thermal environment is also preferred to compensate for reduced solar access in the winter. The extent to which the urban geometry can be optimized for the future climate is also influenced by local urban characteristics.