Search

Urban heat islands (UHIs) are negatively impacting the quality of the urban environment and outdoor thermal comfort (OTC) levels, which have raised concerns regarding their impact on urban health and well-being. Understanding of OTC level is crucial, particularly in tropical cities with year-round high temperatures and humidity. A study was conducted in Kuala Lumpur (KL), Malaysia, to determine the OTC level in a selected urban area through microclimate measurements and questionnaire surveys with 1157 respondents. Over half of the urban dwellers reported thermal discomfort, with a high perceived OTC level, indicating strong thermal adaptive behaviours among the urban dwellers despite the physiological stress. Confounding factors such as urban morphology, land cover and human activity patterns also influence the OTC level in the tropical city. The findings emphasize the need for interventions to improve the urban environment and promote better outdoor thermal comfort for city dwellers through measures such as green infrastructure, UHI mitigation and increasing public awareness. [ABSTRACT FROM AUTHOR]

Abstract Despite its notable role in the exacerbation of urban climate, Urban Heat Island (UHI) was poorly addressed, communicated and integrated into local urban policies of many developing countries. Such scenario often queried the level of UHI understanding amongst the key players who were involved in urban policy formulation. Hence, a qualitative study using Focus Group Discussions (FGD) was designed to investigate the awareness and knowledge level of stakeholders such as policy makers and practitioners in Greater Kuala Lumpur (GKL), an expanding socio-economic hub of a developing tropical country. The findings demonstrated a variable lack of awareness and knowledge about the concept of UHI, its status in GKL as well as organizational engagement in adaptation and mitigation initiatives among the study participants. Essentially, policy makers illustrated a facile awareness and knowledge towards UHI issues whereas practitioners displayed a more robust portfolio of factual understanding regarding the corresponding issues. In line with National Urbanization Policy's (NUP) aspiration to optimize urban developments that provide high quality of life, this study sheds some light on the exigency for UHI awareness creation and capacity building among the policy makers. This study also provides impactful prepositions for the articulation of necessary actions towards evidence-based urban policy formulation in future. Highlights • UHI is poorly addressed, communicated and integrated into local urban policies. • Results demonstrated a variable lack of awareness and knowledge towards UHI amongst the stakeholders. • Impactful insights and recommendations for awareness creation and evidence-based urban policy formulation are provided. [ABSTRACT FROM AUTHOR]

Highlights • Findings revealed positive thermal contrasts between urban and sub-urban stations with maximum UHII during dry period associated with southwest monsoon season. • The results demonstrated that UHI events occurred more frequently at nights in urban stations in the magnitude range of 0–2 °C. • Relative humidity and wind speed display inconsistent association with UHII in urban stations. • Documentation of temporal variations of UHI is essential to understand the influence of urbanization on the deterioration of the thermal regime of well-developed city. Abstract A very few studies have evaluated and understood the temporal dynamics of UHI in many expanding tropical cities. Hence, this study investigated the temporal variations of canopy-level UHI in selected urban stations, namely Petaling Jaya (PJ) and Subang (SUB), of Greater Kuala Lumpur (GKL) using 2016's hourly data set obtained from meteorological observatories. The association between meteorological factors and UHI Intensity (UHII) is evaluated using linear regression models and Pearson correlation analysis. The findings revealed positive thermal contrasts between urban and sub-urban stations with maximum UHII during dry, southwest monsoon season in PJ (June: 1.68 °C) and SUB (August: 1.29 °C) stations respectively. PJ station exhibited a distinct diurnal cycle with the maximum nocturnal UHII of 1.71 °C at about 8 p.m. after sunset under ideal meteorological conditions. The results also demonstrated that UHI events occurred more frequently at nights in urban stations in the magnitude range of 0–2 °C. Cooling at all urban sites starts around 2–3 p.m. with the highest rate of 0.73 °C/h and 0.96 °C/h in PJ and SUB stations. Meanwhile, relative humidity displayed a low positive correlation (r = 0.37, p ≥ 0.05) and a high negative correlation (r = −0.79, p < 0.05) with UHII in PJ and SUB stations respectively. The influence of wind speed on UHII is weak (r = −0.44, p < 0.05) in PJ station and strong (r = 0.83, p < 0.05) in SUB station. Overall, this study can be regarded as one of the comprehensive observational investigations of canopy-level UHI in a tropical city that provide vital inputs to enrich the tropical urban climate literacy. [ABSTRACT FROM AUTHOR]

Urban Heat Island (UHI) phenomenon has become a regional issue for Greater Kuala Lumpur (GKL) as a number of studies reported an elevated air temperature in highly dense urban areas compared to the rural peripheries. An initial literature survey of UHI studies in GKL revealed an insufficiency and paucity of field measurements for more than one decade (since 1991) before gaining its momentum again after 2004. Despite a very limited number of studies in GKL, many studies used a vague set of site classification, operational definitions of Urban Heat Island Intensity (UHII) derived from such vague classification, uncontrolled and old set of data, limited coverage of weather station network and limited number of weather parameters in data collection. Therefore, this paper attempts to provide an overview of UHI studies in GKL by highlighting the major methodological shortcomings that hamper the reliability of previous measurements and by providing vital suggestions for an improved UHI quantification in future. The findings of most of the studies disclose an increasing trend in the UHII which is associated to the reduction in vegetation cover and land use changes. Eventually, this open up new opportunities for the upcoming studies to investigate the sensitivity of UHI to other unexplored factors in the local context. Besides focusing on the role of vegetation on urban temperature reduction, future studies need to focus more on examining the feasibility of other remediation technologies. This paper also suggests that rigorous attention should be given to a systematic site characterization, controlled and synchronous measurements, broader weather station network as well as incorporation of real-time data to elucidate the current UHII status. In addition, local studies could significantly benefit from the utilization of advanced modelling and simulation technologies as a basis for a more informed decision-making in line with the aspiration of GKL to achieve a world class sustainable metropolis by 2020 (GKL Initiative under the National Key Economic Area). Lastly, the incorporation of UHI phenomena in local policies is also essential to mitigate its deleterious impacts via more urban climate-friendly practices by various stakeholders. [ABSTRACT FROM AUTHOR]

• The acceptable range of environmental temperatures was between 25.9 °C and 32.3 °C PET. • 84.7 % of participants were having warm PET, indicates heat stress in outdoor spaces between 1000 and 1700 h. • 57.1 % of participants manifested moderate-to-high severity of somatic symptoms. • Those with warmer PET had 2.44 times higher odds to have a higher severity of somatic symptoms. Rapid urbanization has induced the urban heat island phenomenon which threatens the urban environment and the well-being of communities within it. The prevalence of physical and mental problems associated with hot weather has shown an upward trend recently. However, literature revealed a scarcity of urban health statistics, especially in hot-humid tropical cities. Thus, through this study, we aim to: (1) assess the outdoor thermal comfort of participants in terms of neutral, acceptable and preferred temperatures and (2) examine the association of outdoor thermal sensation and severity of the somatic symptom. A cross-sectional study was conducted by adopting random clustered sampling in a tropical university campus involving 392 healthy individuals aged 18 years and above within 5 m radius from the deployed weather station. Data collection was conducted from April to June 2019 from 1000 to 1700 h. Respondents were required to answer questionnaires that comprise sociodemographic profiles, thermal perception votes, and Patient Health Questionnaire–15 to screen for somatic symptoms. Meteorological data recorded from the weather station was used to evaluate Physiological Equivalent Temperature (PET) using RayMan model. Findings revealed the neutral, acceptable range and preferred temperature to be 25.6 °C PET, 25.9–32.3 °C PET, and 22.1 °C PET, respectively. About 57.1 % of the participants showed moderate–to–high severity of somatic symptoms. After controlling for gender and ethnicity, participants with warm thermal sensation reported 2.44 times higher odds of having moderate–to–high severity of somatic symptoms than those who had neutral physiological thermal sensation (OR = 2.44, 95 % CI: 1.34, 4.43). Gender and ethnicity were the confounders to somatic symptoms. [ABSTRACT FROM AUTHOR]

Highlights • The methodological caveats of OTC studies are addressed. • A holistic approach for future OTC assessment is proposed. • OTC levels are indicators to measure the sustainable liveability of contemporary cities. • Multifactorial studies on ethnic disparities, adaptive thermal behaviour and health implications related to OTC in tropical SEA are needed. Abstract Global climate change, rapid urbanization and population explosion in major cities of Southeast Asia (SEA) are negatively impacting the well-being and liveability of the public in terms of deteriorating outdoor thermal comfort (OTC) levels. However, the available scholarly studies on OTC in the tropical region are insufficient. There is great potential for OTC studies to be used as indicators to measure the sustainable liveability of contemporary cities. As such, there is an immense need for more studies to be conducted in the tropical regions. However, the assessment approaches undertaken in the last decades clearly indicate that there is a need for improvisation. By considering this, this paper provides an overview of published studies that evaluated thermal comfort conditions in the outdoor setting in the tropical context of SEA. Methodological discrepancies and shortcomings are highlighted and discussed to propose a holistic approach for future OTC studies in SEA. The implementation of the proposed holistic approach in the upcoming studies will be beneficial for the improved reliability and integration of findings from studies conducted in various outdoor settings and localities within SEA. [ABSTRACT FROM AUTHOR]