Physiological Equivalent Temperature Index Research Articles

Implementing policies to mitigate urban heat islands: Analyzing urban development factors with an innovative machine learning approach

Taiwan is located in a hot and humid subtropical climate. Urban development, building heat emissions, and human activities lead to the urban heat island (UHI) effect in which urban air temperatures are significantly higher than those in the surrounding suburban areas. In this study, the factors contributing to the UHI effect were investigated in a case study of Taichung City, Taiwan by using high-resolution geographic climate data. Geographic Information System tools were used for grid-based spatial data analysis, and a physiological equivalent temperature index map was calculated and overlaid to identify heat zones. The results revealed that environmental factors have complex, nonlinear effects on temperatures in in urban areas; hence, the analysis was challenging. The decision tree algorithm was used to identified key environmental factors contributing to urban heat in areas with different levels of development; a weighting analysis was then performed to select effective urban cooling strategies. Finally, backpropagation neural network models tailored to different development levels were used for simulations to validate the proposed cooling policies. The results of this study were incorporated into the urban planning policies of Taichung City, Taiwan to mitigate the UHI effect and create a more suitable urban living environment.

Street Design Strategies Based on Spatial Configurations and Building External Envelopes in Relation to Outdoor Thermal Comfort in Arid Climates

Climate change patterns and expected extreme weather conditions drive urban design practices toward more effective adaptation strategies for the built environment. Biskra City, one of the largest urban areas in the Algerian Sahara territory, has suffered from unprecedented extreme weather patterns, specifically during the summer. This paper examined outdoor thermal comfort in the arid climates of Biskra, Algeria, during summer extreme conditions by investigating the impact of the height-to-width (H/W) ratio aspect and the north–south (N-S) and east–west (E-W) street orientations on pedestrian thermal comfort with the parameterization of external building envelopes using brick, concrete, adobe, and limestone materials. This study was conducted with ENVI-met 5.1.1 software, based on 24 parametric scenarios, to identify the most effective composition for outdoor thermal stress mitigation using the physiological equivalent temperature (PET) thermal index. Across all scenarios, the PET index values fluctuated between PETmin = 32.2 °C and PETmax = 60.6 °C at different hours. The coupling between the H/W ratio and street orientation as geometry factors and building envelope characteristics reveals six distinct categories of building materials, each with an impact on outdoor thermal comfort: (1) high cooling (60–100%), (2) medium cooling (40–60%), (3) low cooling (<40%), (4) high heating (60–100%), (5) medium heating (40–60%), and (6) low heating material (<40%). Therefore, in the N-S orientation, limestone walls can provide a cooling efficiency range from 85% to 100% throughout deep and shallow canyons. Contrary to this, brick walls can cause a heat retention range varying from 70% to 93% within the same canyons. When considering extreme summer conditions in arid climates, the results show that the most effective bioclimatic passive strategy that could be achieved is the E-W orientation, within H/W < 1, characterized by a high albedo building material.

The effect of facade materials and coatings on urban heat island mitigation and outdoor thermal comfort in hot semi-arid climate

High urban temperature is generally associated with negative effects on building energy consumption, outdoor thermal comfort, air quality, and human health. Then it is necessary to find strategies to reduce urban heat island and improve outdoor thermal comfort. This research investigates and classifies facade coatings and materials with regards to urban heat island effect in hot semi-arid climate of Shiraz. The surface temperature of 20 common and modern building facade materials during two periods for five days and their effect on outdoor air temperature is investigated through field measurement. Additionally, to study the effect of each material on urban heat island and thermal comfort index, Physiological Equivalent Temperature (PET) of a neighborhood in Shiraz was simulated with ENVI-met software on June 22. The results show that during the day under direct sunlight, the living wall has the lowest surface and air temperatures, and as the nearby air temperature increases during the night, it lowers the temperature fluctuations both during the day and night. Materials with high albedo increase the Mean Radiant Temperature and PET index despite their lower surface temperature. Materials with high thermal mass and low emissivity have lower temperature. The living wall has the lowest PET index, indoor and outdoor surface temperature during the day. It can also result in 2 °C reduction of air temperature.

Towards local sustainability: A case study to evaluate outdoor urban spaces in Baghdad using physiological equivalent temperature index

Improving environmental quality to promote outdoor activities, which also aims at providing social benefits, is an extensively researched field of study. In this study, a sustainable urban solution is evaluated as a prototype using the physiological equivalent temperature (PET) index. The literature demonstrated the local deficit of increasing social qualities through the development of a prototype that performs as a mitigation strategy to improve the urban thermal environment. To fill this gap, the aim of this experimental study is to create a neutral outdoor thermal comfort area that is suitable for social gatherings while minimizing local heat stress. We investigated six selected sites using ENVI-met 4.4 software, and we validated them with the observed data by two types of validation metrics. The sites were located near the Tigris River in Baghdad. The conditions at the sites were analyzed between 8:00 and 24:00. The simulation findings revealed the possibility of achieving thermal comfort during most of the working hours. A reduction in thermal stress by ∼18.4 °C was observed with a drop of 36.4% of PET results. The urban solution contributed to a decrease in the temperature by four degrees from the existing situation, which promotes a sustainable outdoor urban area. In hot climates, any outdoor activity between 12:00–16:00 is generally discouraged, whereas (8:00–10:00 & 18:00–00:00) hours are suitable for social interaction. However, multistoried buildings with sufficient orientation and shading could be ideal for achieving local sustainability, whereas the river's presence and its low albedo significantly raise the mean radiant temperature (MRT) by ∼7–8 °C, which proves its importance in heat reduction. The hybrid fabric altered the traditional courtyard's climatic characteristics, exacerbating its heat stress. The largest dip in PET in the courtyard area occurred at 17:00, with a drop of 13.6 °C, which was smaller than the rest of the areas. The additional sustainable prototype had a significant impact on influencing the microclimate and played a decisive role in determining thermal comfort. The prototype's high- albedo materials and dense, selective local trees have a direct effect on reducing the local air temperature and MRT. This, together with the physical characteristics of the surrounding area, helped to minimize PET outcomes and improve the local thermal environment. The findings of this study serve urban designers by verifying the success of the modelled design prototype spatially and environmentally.

Investigating the impact of using modified cool materials by titanium dioxide (TiO2)-based photocatalytic self-cleaning nanoparticles in urban facades on urban microclimate parameters

PurposeOn the one hand, one of the most important global strategies to improve thermal comfort in urban spaces is using cool materials (high albedo materials) in urban facades. On the other hand, using cool materials in urban facades is a big challenge. Over time, the albedo of cool materials that modified by titanium dioxide (TiO2)-based photocatalytic self-cleaning materials (PSTiO2) does not decrease. In fact, its self-cleaning property prevents the loss of the initial albedo of the material. The self-cleaning performance of these materials was investigated in previous researches. However, their thermal performance in urban space has not been investigated yet. This paper studied the performance of these materials on the urban square facade. Design/methodology/approachThe thermal performance of PSTiO2 on the thermal comfort of the urban square was evaluated by ENVI-met(v4). The results simulated by ENVI-met software with field measurements in the urban Square were compared. Field measurements of air temperature were conducted on 22 July and 30 March. FindingsThe results showed that these materials, despite their self-cleaning properties, have significant thermal impact in the urban environment. Using plaster modified by PSTiO2 (albedo 0.6) improved slightly by nearly 0.2 °C the thermal comfort of the urban square. Whereas, white paint modified by PSTiO2 (albedo 0.9) reduced the physiologically equivalent temperature (PET) by 0.5 °C, because reflection of solar radiation increased between the buildings facades. The simulation results showed that due to the space is more enclosed in the square entrance, the mean radiant temperature (Tmrt) increased. As a result, PET index rose too. Originality/valueThis study shows that employing cool and self-cleaning materials in the urban facades of Jolfa Square, in addition to have self-cleaning property, is effective in the amount of thermal comfort of the square. In the parts of the square where the enclosure is less, an improvement in thermal comfort was observed. The performance of the cool and self-cleaning materials in the facade in terms of thermal comfort is completely dependent on the physical parameters of the urban space.

Spatial Distribution and Future Projections of Thermal Comfort Conditions during the Hot Period of the Year in Diyarbakır City, Southeastern Turkey

Cities are highly vulnerable areas affected by climate change. For sustainable urbanization, it is of great importance to determine the thermal conditions in cities and to make predictions for the future. Therefore, in this study, the spatial distribution of the thermal comfort conditions in the city of Diyarbakır, located in the southeastern Turkey, during the hot period of the year is explained and predictions for the future are made. In the study, measurement data from meteorological stations and the data of the SSP-2 and SSP-5 scenarios were used. Thermal comfort conditions were determined according to the PET (physiological equivalent temperature) index using RayMan software. The ArcGIS 10.5 program was used for defining the spatial distribution of thermal comfort conditions. As a result of the study, it is seen that the areas with dense construction and a low amount of green area in the old urbanized area, which is the central business district (CBD), have uncomfortable conditions. It is predicted that uncomfortable areas will increase in the near and distant future and threaten human health. For climate-resilient, healthy, and comfortable cities that can adapt to adverse effects of climate change, urban design and planning should be carried out with a holistic perspective.

Analysis of Spatial Distribution of Climatic Comfort Conditions in Diyarbakır City

Cities have more adverse thermal comfort conditions than the rural and semi-rural areas around them. In this study, it is aimed to examine the spatial distribution of thermal comfort conditions in Diyarbakir, a historical city in the Southeastern Anatolia Region of Turkey. Thermal comfort can be defined as the state of people feeling comfortable or happy in their environment or thermal environment. Uncomfortable conditions lead to social, economic and physical negativities, especially to human health. Thermal comfort conditions were calculated with the Physiological Equivalent Temperature index obtained from the RayMan model using hourly measurement data for the 2015 – 2021 (7 years) period of four meteorological stations in the field. In the study, while 'cold' and 'cool' stresses are experienced in the winter season in Diyarbakır, 'warm', 'hot' and 'very hot' stresses were determined in the 5-month hot period of the year (May-September). In the evaluations, it has been revealed that densely built urban areas in the city center have more unfavorable thermal conditions than the lower density urban areas and rural areas around them. It is a vital necessity to design and plan with a contemporary smart geographical perspective to reduce the negative thermal conditions of cities and for sustainable healthy cities.

The Influence of Residential Block Form on Summer Thermal Comfort of Street Canyons in the Warm Temperate Zone of China

The residential block is the cognitive unit for residents to constitute urban imagery. As one of the most frequently used urban outdoor public spaces by residents, the thermal comfort of street canyons is an essential indicator for assessing sustainable and livable cities. The problem of the uncomfortable summer climate in the warm temperate zone of China has not been adequately studied. The study aims to analyze the influence of the building layout form of residential block units and block configuration on the outdoor summer thermal comfort of street canyons. Outdoor air temperature (Ta), mean radiant temperature (Tmrt), wind speed (Va), and physiological equivalent temperature (PET) were simulated using ENVI-met. A new index, PETws, was introduced based on a statistical analysis of the PET index to assess the overall street canyon thermal comfort of the block. The results indicate that the number of rows of buildings in the building row layout has a more significant effect on the summer thermal comfort PET of street canyons than the number of columns in the warm temperate zone, especially on N–S-oriented streets. Reducing the number of rows can increase the overall thermal comfort PETws of street canyons by a maximum of 2.2%. The best choice for the number of building columns is two columns. Adopting different block configurations can increase the thermal comfort PETws of street canyons by up to 2.5%. An optimal block form has been created to improve the overall street canyon summer thermal comfort of the block.

A decision-making framework for promoting the optimum design and planning of Nature-based Solutions at local scale

Urbanization is a key driver of land use/land cover changes climate change. It produces a reduction in natural capital with alteration to the energy budget of land, air ventilation and land surface temperature. The urban morphology derived from the combination of natural capital and human-derived capital is important in urban ecosystem services (UESs) provisioning to mitigate the Urban Heat Island (UHI) effect. Here we report a decision-making framework starting from an applicative case study to assess UESs and promote the best design and planning of Nature-based Solutions (NbS) at local scale. The human thermal comfort has been chosen here as a surrogate to estimate climate regulation as a priority UES in mitigating UHI. The analysis of human thermal comfort in different urban neighbourhood planning scenarios of a city located in Southern Italy has been carried out using the microclimate model ENVI-met. The analysis has been developed to highlight the variation in human thermal comfort in terms of Physiological Equivalent Temperature index (PET) between past agricultural scenarios (no longer more present), current state and several proposed urban scenarios. Such new scenarios have been developed by considering different building arrangements according to municipal planning rules of the city and choosing different types of NbS composition and structure. The analysis has allowed to identify the best scenario characterized by the presence of a community garden with olive groves and estimate the capacity of NbS to reduce the human thermal comfort by about 3.5ºC and improve the PET in selected locations within the current state. In accordance with the aim and topics of the Special Issue, this study shows how such a framework can be useful to support decision-making processes in choosing the best strategy in terms of urban plans and thus making the urban transformation process more sustainable, contributing to assessing the global targets of the 2030 Agenda at local scale.

The Effect Of Urban Areas On Human Bioclimatic Comfort Conditions; Sample Of Amasya City

Urban settlements, one of the most important developments in the history of humanity, expanded due to the migration movements from rural to urban areas and turned into dense and high-built settlements. This situation has caused urban areas to have different climatic conditions from the suburban and rural areas around them. Bioclimatic comfort is the state of people to feel comfortable, happy and fit in the atmospheric environment they are in. Uncomfortable conditions cause much negativity such as decrease in people's work efficiency, health conditions and increase in energy consumption. Amasya is a small Anatolian city in the Central Black Sea Region of the Black Sea Region, where industrialization has not developed. In this study, hourly data of the year 2021 of two meteorology stations, which are considered as urban and suburban, were used in order to examine the effects of urban areas on bioclimatic comfort conditions in Amasya. As a method, the PET (Physiological Equivalent Temperature) index obtained from the RayMan model, which calculates many factors together, was used. As a result of the study, suburban is 2.1 ˚C cooler than urban at the general PET average; 3.4˚C cooler at the maximum average and 2.8˚C cooler at the minimum average. The urban area is exposed to heat stress by 8.1% more throughout the year than the suburban area. In order to reduce the negative bioclimatic comfort conditions of cities and for sustainable urbanization, it is necessary to make urban design and planning that takes into account human, ecological and physical conditions.

Evaluation of the relationship between thermal comfort conditions and respiratory diseases in Amasya City, Turkey.

Studies examining the relationship between thermal comfort conditions-the state of feeling insulated against atmospheric factors in the environment-and diseases have been very limited. In Turkey, which is in the transition zone of air masses in middle latitudes, thermal comfort conditions change frequently due to sudden weather changes. This study was conducted to examine the relationship between thermal comfort conditions and respiratory diseases in Amasya, an exemplary Turkish city in the Black Sea Region of Turkey. To determine the thermal comfort conditions in the study between 2017 and 2019, the PET (physiologically equivalent temperature) index obtained from the RayMan model was used for data including hourly air temperature (°C), relative humidity (%), wind velocity (m/s), and cloud cover (octa). Daily air temperature data were also obtained. The relationship between PET values and air temperature and respiratory disease hospital admissions was analyzed by Pearson correlation analysis and linear regression analysis. The results revealed a very high negative correlation between both thermal comfort conditions (PET) and air temperature and respiratory diseases (p < 0.000). The results show that with an increase of 1 °C in thermal comfort conditions (PET), hospital admissions due to respiratory diseases will decrease by approximately 64 to 67 patients. It is predicted that the number of patients will decrease by approximately 89 to 94 with an increase of 1 °C in air temperature. These findings can be informative and serve as guidance for decision-makers in efforts to protect public health, for preventive medicine studies, and for studies on the effects of climate change on human health.

The relationship between thermal sensation and cardiovascular patients’ admission rates in Tabriz, Iran

Atmospheric conditions in any place can affect people's health. In recent years, researchers have focused on heat stress and its effect on the exacerbation of some diseases. The main objective of this study is to identify the bioclimatic conditions and its relationship with the admission rate of cardiovascular patients in of Tabriz city. In addition to meteorological variables, daily cardiovascular patient admission rates were obtained from Shahid Madani Heart Hospital in Tabriz during the statistical period of March 27th, 2007 to February 17th, 2017. To do so, the bioclimatic conditions of Tabriz were identified on a daily scale based on bioclimatic indices including Perceived Temperature (PT), Physiological Equivalent Temperature (PET) and Predicted Mean Vote (PMV). Then, the relationship between each bioclimatic condition and the number of cardiovascular patients' referrals in Tabriz was investigated using Kruskal-Wallis test. Findings illustrated that the impact of cold stress in the rate of cardiovascular patients was more than that of the warm stress, which was obtained for all study indicators in a similar way. On the other hand, the results showed that based on PET and PMV indices, there is a significant difference between various bioclimatic classes in the rate of cardiovascular patients' admission. The results of Kruskal-Wallis test include Sig = 0.040 and Sig = 0.049 for PET and PMV, respectively. However, Sig values for and PT indice showed no significant difference between bioclimatic classes in the rate of admission of cardiovascular patients. Generally, it was found that there is a significant difference (Sig = 0.000) between the three classes of bioclimatic cold, warm and comfort with the number of hospital admissions of cardiovascular patients.

Calibration of the Physiological Equivalent Temperature (PET) index range for outside spaces in a tropical climate city

This study aimed to calibrate the physiological equivalent temperature (PET) index range for Cuiabá-MT, a city with a tropical climate, for which PET calibration was not previously conducted. The air temperature, relative humidity, globe temperature, wind speed, and direction were measured in three scenarios: arboreal shading (S1), artificial shading with parasol (S2), and sun exposure (S3). Questionnaires were administered to a group of 30 people to verify the preferences, perceptions, and levels of thermal comfort of respondents with data processing, using RayMan software. The values with the greatest differences were between S1 (wooded) and S3 (sun exposure). Five categories of the PET index were adapted: slightly cold, comfortable, slightly hot, hot, and very hot. The comfortable range was found to be between 23.01 and 34.64 °C. When performing the correlation of the users' responses regarding their thermal perceptions and preferences in the different scenarios, it was found that in S1, the percentage of thermal comfort was the highest and in S3, the percentage of thermal discomfort was the highest, reinforcing the significance of afforestation in thermal comfort. The findings of this study contribute to the clarification of issues related to thermal perception and comfort in open spaces in tropical climate.

Predicting climate change impact on hospitalizations of cardiovascular patients in Tabriz

Atmospheric conditions in any place can affect people's health. In this regard, this study aimed to investigate the climatic conditions of Tabriz (in northwestern Iran) and their relationship with the admission rate of cardiovascular patients in this city. We sought to predict thermal stresses on the hospital admissions rate of cardiovascular patients for the 2030s to 2059. The results of two climate models of CanESM2 and GFDL and three scenarios of RCP2.6, RCP4.5, and RCP8.5 were used to predict climate changes in the coming decades. In the present study, the physiological equivalent temperature (PET) index was applied to monitor and predict thermal stresses. The findings revealed that the colder the PET class, the higher the average of admissions. Based on all climate models and scenarios, it was found that the increase in hospital admissions for the middle classes of the PET index will be more than that of the extreme classes. On the other hand, the effect of global warming will cause an increase in the number of cardiovascular patients at an average rate of 147 people per year.

Influence of Vegetation on Outdoor Thermal Comfort in a High-Altitude Tropical Megacity: Climate Change and Variability Scenarios

The objective of this paper is to show a study on the influence of vegetation on the outdoor thermal comfort (OTC) of a high-altitude tropical megacity. The OTC is evaluated by the PET (Physiological Equivalent Temperature) index and by establishing three simulation scenarios: (i) Current OTC, (ii) OTC under RCPs 4.5 and 8.5 (Representative Concentration Pathway), and (iii) OTC under RCPs and ENSO (El Niño–Southern Oscillation). The results show that the hourly variation range of the current OTC in urban areas with vegetation is greater (+3.15 °C) compared to impermeable areas. Outdoor thermal stress due to cold in vegetated areas is 1.29 °C lower compared to impervious areas. The effect of vegetated coverage on the improvement of urban OTC increases as the phenomenon of global warming intensifies. On average, in the current, RCP4.5, and RCP8.5 scenarios for each 10% increase in urban vegetation coverage, an increase of 0.22, 0.24, and 0.28 °C in OTC is obtained, respectively. The hourly variation range of the PET index increases during the ENSO scenario (vegetated areas: +16.7%; impervious areas: +22.7%). In the context of climate change and variability, this study provides a reference point for decision-makers to assess possible planning options for improving OTC in megacities.

The effect of height and orientation of buildings on thermal comfort

The purpose of this study is to investigate the climatic and natural capabilities to optimize open spaces. Two physical indicators, the ratio of the height of buildings to their distance from each other (H/W) and the orientation of buildings towards the street, were examined as the most critical factors affecting outdoor comfort conditions. Regarding the aspect of H/W, ratios of 0.5, 1, 1.5, and 2 were selected, which represent buildings with 3 to 13 floors at a distance of 20 m from each other. Also, about the orientation factor, angles of 135° to 200° clockwise from the north were examined. This study was conducted in Tabriz with a dry climate, cold winters, and relatively hot summers. For simulating different scenarios, Envi-met and Rayman were used. Three factors of air temperature (Ta), mean radiant temperature (Tmrt), and physiological equivalent temperature index (PET) were examined as essential factors of thermal comfort. For validation, local and field data on a simulated day were compared with the data extracted from the software. The results show that considering summer and winter, the ratio of H/W = 1.5 and the angle of 135° from the north are the most suitable.

Architectural Simulations on Spatio-Temporal Changes of Settlement Outdoor Thermal Environment in Guanzhong Area, China

This paper aims to provide data support for rural sustainable development through analyzing the spatio-temporal characteristics of the interactions of the outdoor thermal environment. The ordinary and representative rural settlements in the Guanzhong area were selected to analyze the dynamic process of the rural thermal environment through field measurements and numerical simulations. RMSE (root mean square error) and MAPE (mean absolute percentage) were used to verify the numerical simulation model, and physiological equivalent temperature (PET) was used to evaluate the outdoor thermal environment. Results show that the ENVI-met model reliably predicts the thermal environment of a rural settlement, as the air temperature and relative humidity values range of the RMSE and MAPE were 0.85–1.79 and 2.04–5.11%, respectively. Moreover, the air temperature rose by 3.08% and relative humidity dropped by 4.42% from 2003 to 2018 as the amount of artificial surfaces increased by 35.4% and the PET index gradually increased by 27.43% at daytime and 34.03% at nighttime. Furthermore, trees could improve the outdoor thermal environment significantly, mainly because the average air temperature decreased by 3.6% and relative humidity increased by 8%, and the PET index decreased by 12.4% and 13.1%, respectively, for daytime and nighttime. This case study is representative of rural settlements in the Guanzhong plain, and thus is an appeal to rural planners to pay attention to the thermal environment issues caused by increased artificial underlay surfaces and to focus on trees in rural areas.

Crowd Gathering and Thermal Comfort Research in Different Park Shading Spaces

The thermal comfort of different shaded spaces in parks varies noticeably, and it is also a key factor influencing crowd gathering. Longzi Lake Beach Park in Zhengzhou was used as a study area in this research. For analysis, a thermal comfort index for three different space types (unshaded, semi-shaded, and fully-shaded) and a crowd aggregation index were used. The results show that during autumn, visitors are sensitive to the thermal comfort in different shaded spaces, and that the location of the playing field differs significantly. Air temperature and solar radiation are the two factors that influence tourists’ thermal comfort the most. For the first time, a regression relationship between physiological equivalent temperature (PET) and mean thermal sensation vote (MTSV) is established in different shading spaces. It clarified the thermal comfort of tourists in different shaded spaces. PET and crowd aggregation index show a clear correlation. The correlation between the MTSV and crowd aggregation density increased with the increase in shade area. For the first time, the relationship between thermal comfort and crowd gathering in different shaded spaces in parks was analysed. The research is beneficial to improving the scientificity of the construction of the park’s thermal environment, and providing people with more comfortable outdoor space from the perspective of shading.

Evolution of Heat Index (HI) and Physiological Equivalent Temperature (PET) Index at Mumbai and Pune Cities, India

In the present study, trends in heat stress during summer and monsoon season months were assessed for two cities, Pune and Mumbai, for the period of 47 years from 1969 to2015 with the application of empirically derived Heat Index (HI) and rational heat balance based Physiological Equivalent Temperature (PET) index. A stepwise multiple regression analysis was applied to determine contributing meteorological parameters responsible for changes in heat stress incidences. The study reveals a considerable increase in heat stress during the summer months over Mumbai compared to Pune city. Similarly, during the end months of monsoon season, thermal discomfort conditions aggravate over both the cities, with statistically significant rising trends. The actual identification and categorization of thermally discomfortable days during the study period in accordance with the Heat Index were moderate. They remained consistent in Pune during summer, however, in monsoon, heat stress incidences were meager. While at Mumbai days with 'High' and 'Very High,' heat stress have increased towards recent years. Categorization according to PET index depicted conspicuous presence of 'Strong' and 'Extreme heat stress' at Pune, while at Mumbai, 'Warm' and 'Hot' days portrayeda slight increase. The assessment of meteorological parameters depicted that increased humidity and temperature were the main concern for the increase in heat stress over Mumbai. In contrast, mean radiant temperature, ambient air temperature with restricted wind speed leading to high sensible heat may be responsible for the significant increasing trend in PET. The study infers that both the cities are vulnerable to escalating heat stress and may have adverse implications on the health of city dwellers.

Short-Term Particulate Matter, Ultrafine Particles, and Blood Pressure among Children of the CorPuScula Study in Munich, Germany

BACKGROUND AND AIM: Short-term changes in particulate matter (PM) have been linked to blood pressure, but limited evidence exists on effects among children and for ultrafine particle (UFP) exposures. METHODS: We used data from 50 children (ages 6-10) in the German CorPuScula study, in which children attended up to 30 school health examinations in 2001 and 2002. Systolic and diastolic blood pressure (SBP and DBP, respectively; mmHg) were collected at each examination after children had rested for at least 5 minutes. PM10 (diameter ≤10 µm; µg/m3) and PM2.5 (diameter ≤2.5 µm; µg/m3) levels were measured at school using a low volume sampler for the entire study period, and UFPs (n/mL) were measured for six months using a particle counter. All exposures were evaluated for same-day working-hours (9:00-21:00) as well as one- and two-day lags, with UFPs also assessed for the 1-, 3-, 12-, and 24-hours prior to examination. Associations between air pollutants and blood pressure were evaluated using mixed linear regression models with a random participant intercept and adjusted for weekday as well as study day and physiological equivalent temperature index using natural cubic splines. Multipollutant models were conducted adjusting for centrally-monitored NO2. RESULTS:For the PM data (nobs=1,079; average 22 observations/child), median daily PM2.5 levels were 12.7 µg/m3. In the UFP data (nobs=420; average 8 observations/child), median daily UFP exposures were 21,544 particles/mL. We observed positive associations between PM and SBP that attenuated slightly upon adjustment for NO2, with strongest associations for 2-day lags (e.g., 1.45 mmHg [95% Confidence Interval: 0.78, 2.11] increase in SBP per 13.4 µg/m3 increase in PM2.5). PM10 was weakly inversely associated with DBP. No associations between UFP exposures and either outcome were apparent. CONCLUSIONS:While positive associations were observed between PM and SBP, we observed no evidence that UFP exposure influences blood pressure in children. KEYWORDS: Children's environmental health, Short-term exposure, Air pollution, Cardiovascular diseases, Multi-pollutant