Physical, Psychological, and Social Health Impact of Temperature Rise Due to Urban Heat Island Phenomenon and Its Associated Factors

The Urban Heat Island Effect (UHI) has now become a commonly observed phenomenon worldwide. Indeed, it has become a significant environmental effect of urbanisation. In Malaysia, research results showed that UHI effects are very evident in several cities such as Kuala Lumpur and Putrajaya^{[1, 2]}. UHI effect has long been observed to cause temperature of cities. Temperature rise associated to UHI phenomenon may have a profound impact on the health and welfare of urban residents. Physical health impacts of temperature rise in urban cities have been the subject of numerous studies worldwide and have been reported more frequently in recent years in both Western and Asian regions^[3]. Among the most important effects of temperature rise on physical health is the exacerbation of pre-existing chronic diseases, particularly cardiovascular, and respiratory disorders, respiratory illnesses as well as outright heat exhaustion and heat stroke^[4]. Climate change and ongoing trend of increase temperature also has tremendous impact of manifestations of vector borne diseases such as malaria and dengue^[5].

Temperature rise also impacts psychological health. Increased temperature is associated with depression and anxiety, emotional disturbance and aggression; there is evidence that it may exacerbate psychotic or depressive illnesses. High temperature has also been linked to increased mortality from mental and behavioural disorders and psychoactive substance use^[6]. Rising temperatures in the cities also bear a profound effect on people's social health. Research indicates that higher temperatures affect social interactions, connectivity, social networks, influence occupational performance as well^{[6, 7]}.

The health impact of temperature rise, particularly psychological, and social health, on the city community in Kuala Lumpur city has never been extensively studied. Physical illnesses related to air pollution and poor air quality in Kuala Lumpur have been reported^[1], but not investigated in detail. We conducted a study that assessed the knowledge, attitudes, prevention practices, and health impact of temperature rise associated to UHI in Greater Kuala Lumpur, Malaysia. The detail findings on knowledge, attitudes, and prevention practices were reported comprehensively elsewhere. This paper is the first to report on the impact of temperature rise associated to UHI on psychological and social health in Malaysia. Most importantly, the paper first describes the extent to which temperature rise affects the physical, psychological, and social health of the residents of Greater Kuala Lumpur. Secondly, factors that associate with temperature rise on health will also be illustrated.

The sample was drawn from Greater Kuala Lumpur. In this study, three areas in Greater Kuala Lumpur were randomly selected. These were (1) Mont Kiara, (2) Jalan Raja Chulan, and (3) Setia Alam. Interviews were conducted using computer-assisted telephone interviewing between October 2016 and May 2017. Sampling was drawn by random digit-dialling of landline phone numbers from all the three study areas. The selection of respondents within contacted households was accomplished by randomly requesting to speak to adults (18 years of age or older) residing in the household.

The questionnaire was developed by the researcher based on a literature review, and adjusted to fit the study objectives. Subsequently, face and content validation testing of the questionnaire was conducted panel of experts. The expert panel members were requested to evaluate the content relevance of the questionnaire. The content validity was determined by computing a content validity index (CVI) based on the experts' ratings of item relevance. The range of CVI was 0.8 to 1.0. The questionnaire was revised and the final draft version of the questionnaire was pilot tested.

The questionnaire consisted of three sections. In the first section, demographic data were collected. In the second section, respondents were asked about their living environment, which included questions on building types, how the building is cooled, and the number of people living in the household. The third section queried respondents about UHI and temperature rise (its causes, consequences, and health impacts). Knowledge of health impacts included physical, psychological, and social health impacts. The total number of knowledge item questions was 29 items. Response options were either 'yes', 'no', or 'don't know'. Knowledge questions were scored as follows: one point was given for each correct answer and a 0 was given for wrong answers or don't know responses. The total knowledge scores ranged from 0-29, with higher scores indicating a higher level of knowledge of UHI. The internal consistency, as measured by Cronbach's alpha coefficients was 0.955 (range 0.596 to 0.704).

In the fourth section, respondents were queried about any health impact they have experienced (physical, psychological and social) that are related to temperature rise associated to UHI. Physical health impact consisted of seven items; physiological health consisted of four items, and social health consisted of three items. Internal consistency was 0.941 (range 0.690 to 0.900). Response options were either 'yes' or 'no'. Health impact questions were scored by giving one point for 'yes' response and zero points for 'no'. The total health impact scores ranged from 0-14, with higher scores indicating a higher level of health impact from urban heat.

The fifth section addressed health belief questions (total of five questions). The study used the Health Belief Model (HBM)^[8] as a framework to understand how the public's perceptions of benefits, threats, cues to action, and self-efficacy affect the likelihood of them becoming involved in practicing control measures to reduce UHI effect. The HBM constructs have been used to explain the adoption of preventative behaviours and healthy lifestyles, as well as illness prevention practices^[9].

The sixth section consists of questions on practices to reduce temperature rise associated to UHI. The practices section consists of four subsections that queried respondents on practices to mitigate UHI impact on personal physical health, environmentally responsible practices, green infrastructure, and transportation-related practices. The total number of questions was 16. Response options were either 'yes' or 'no'. These questions were scored by giving one point for 'yes' responses and zero points for 'no'. The total practices scores ranged from 0-16, with higher scores indicating a higher level of control practices against the effect of UHI. Cronbach's alpha coefficient for practices items was 0.935 (range 0.344 to 0.861).

Informed consent was obtained verbally. The study was approved by the University of Malaya Medical Ethics Committee (MECID NO: 2016928-4295). Due to word limitation, this manuscript reports finding of health impact associated to UHI phenomenon. The detailed findings of knowledge, attitudes, and mitigation practices of this study have been submitted elsewhere.

Data were statistically analysed with SPSS statistics version 19.0 (SPSS Inc., Chicago, USA). All mean total scores were subjected to normality tests to explore their normality distributions. As all the mean total scores were not normally distributed, K-means clustering was performed to cluster the scores with similar patterns into two^[10]. To evaluate the factors associated with mean total health impact score, the Chi-square test was used to examine the univariate associations between each of the factors (the independent variables) and the clusters for total scores for health impact. Multivariable logistic analysis was subsequently carried out if there were two or more significant associations (P < 0.05) in the univariate analysis. All significant variables in the univariate analysis were entered into the multivariable logistic regression analysis using a simultaneous forced entry model (enter method).

A total of 558 participants completed the survey (response rate was 40%). As shown in Table 1, a high proportion of participants reported experiencing the health impacts queried in this study. On average, the proportion of respondents that experienced physical and social health impacts associated with temperature rise was higher than the proportion that experienced psychological impacts. Heat exhaustion (89.4%) and respiratory problems (87.3%) were the most commonly reported physical health impact. As for psychological health impact, the highest reported was anxiety (79%), followed by depression and aggressive behaviour. Reduced outdoor activities (90.0%) were the most commonly reported social health impact associated with temperature rise. The health (physical, psychological, and social) impact items were totalled, and the mean total health impact score was 11.17 ± 4.17. The total health impact score reported by study participants ranged from 0 to 14.

Table 2 shows the correlation between total mitigation practices score and total health impact score. High correlation coefficients were found in all the associations. In particular, the highest correlation was found between total mitigation practices score and total social health impact score (r = 0.809). The univariate analysis in Table 3 shows that the middle age group, professional and managerial and manual workers, and higher household income group (MYR 4500) have higher total health impact scores. Higher knowledge and mitigation practices scores were also significantly associated with higher total health impact scores. Higher perceived susceptibility, perceived severity, perceived benefit of carrying out prevention measures, and perceived barriers to prevent UHI were associated with higher total health impact scores.

In the multivariable regression analysis, only total knowledge and mitigation practices scores were significantly associated with total health impact scores. Respondents with total knowledge scores of 20-29 had higher odds of having higher total health impact scores [Odds Ratio (OR) = 10.465; 95% Confidence Interval (CI) 4.309-25.415]. Respondents with total mitigation practice scores of 12-16 reported higher odds of having higher total health impact score (OR = 26.671; 95% CI 1.490-61.909).

This study indicates that a high rate of study participants experienced various adverse health impacts. This high prevalence of adverse health impacts reflects the severe effect temperature rise associated to UHI has on the city residents in Malaysia. The three most prominent physical health effects found in this study, namely heat exhaustion, respiratory problem and heat stroke, replicate previous research findings^[4]. These findings have implications for decision makers and researchers who want to estimate the effect of urban heat on the health of the city community in Malaysia. Because heat exhaustion and heat stroke were commonly reported by study participants, decision makers should implement prevention measures, such as educating city residents so that they can more readily identify symptoms and obtain the medical help they need.

The current study also found a profound increase in vector-borne diseases. Vector-borne diseases, principally dengue, remain a major public health challenge in Malaysia. Vector-borne diseases are among the most well studied of the diseases associated with climate change and temperature rise, owing to their large disease burden, widespread occurrence, and high sensitivity to climatic factors^[5]. These results suggest the need for strengthened surveillance for vector-borne infections and for increased capacity to rapidly respond to vectorborne disease outbreaks in Kuala Lumpur, Malaysia.

A more groundbreaking finding was the high prevalence of psychological health impacts on our city communities. Likewise found in other study, temperature rise exacerbates psychological and mental health disorders has been widely reported^[6]. More attention should be given to the variety of psychological health impacts caused by urban heat. Further, climate change was also found to intensify substance abuse such as alcoholism and drug addiction^[6]. The impact of climate change on substance abuse was not investigated in this study, but it should be a focus for future study. Because climate change is likely to affect mental health in many ways, health professionals should assist in creating adaptation and mitigation measures that will help individuals adapt to the changing environment and will help reduce emotional and psychology impacts.

Another important finding was the significant association between mitigation practices and all three components of the health impacts investigated in this study. The association remains significant in the multivariable analysis; higher mitigation practices were reported among participants who had higher health impacts. In this study, it was also found that higher knowledge also associated with higher health impacts. This result suggests the importance of promoting environmental health literacy to city residents. Health literacy has been linked to preventive behaviours. Because health literacy is an outcome of health promotion, health promotion in the urban community is a necessary step in building resilience to climate changes such as UHI.

The study also found that a person's positive beliefs about UHI influence health impact of temperature rise. Although the associations found in our multivariable analyses were not significant, findings in the univariate analysis may suggest that having higher perception of susceptibility, higher perception of severity, and higher perceived benefit from prevention behaviour could attenuate the health impacts. Findings of this study suggest the use of HBM in promoting behavioural change in future health promotion intervention.

This study has several limitations. The cross-sectional design of the study may diminish the ability to infer direction of causality. A longitudinal design would better enable the determination of causality. The second limitation was that the study may lack representativeness, as households with no landline telephone are not represented. Another potential limitation of the telephone interview includes interviewer biases and response biases. Further, this study did not assess important factors such as seasonal, diurnal and climatic factors that also has an important influence on heat-related morbidity. The last limitation is that the health impact data was gather using self-reported questionnaire rather than actual hospital records. Self-report methods possess limitations in terms of their reliability and validity. Future study should be conducted using data recoded in hospitals to increase validity.

Pronounced physical, psychological, and social health impacts associated with urban heat were evident. Study found high rate of psychological distresses namely anxiety, depression, and aggressive behaviours. Level of socialization were reduced and prominent physical health impact such as heat exhaustion, respiratory problems and heat stroke. The results of this study highlight the importance of health impacts of increased temperature on the city community in Greater Kuala Lumpur, Malaysia. More interventions should be developed to impart knowledge and encourage the city community to engage in measures to counter the effects of urban heat and maintain optimal well-being. The findings of this study also suggest that the use of HBM in promoting behavioural change in future health promotion intervention. The factors influencing health impacts found in this study can and should inform policy and public health responses to mitigate the effects of urban heat.