Spatiotemporal patterns of urban heat in indoor and outdoor microclimates

Given the possible role of spectral composition of light and myopia, this study aimed at investigating the variation in the spectral composition of ambient light in different (a) outdoor/indoor locations, (b) time of a day and (c) seasons. The spectral power distribution (SPD), categorised into short (380-500 nm), middle (505-565 nm) and long wavelengths (625-780 nm), was recorded using a handheld spectrometer at three outdoor locations ('open playground', 'under shade of tree' and 'canopy') and three indoor locations ('room with multiple windows', 'closed room' and 'closed corridor'). Readings were taken at five different time points (3-h intervals between 6:30 and 18:00 hours) on two days, each during the summer and monsoon seasons. The overall median SPD (IQR [25th-75th percentile] W/nm/m2 ) across the three outdoor locations (0.11 [0.09, 0.12]) was 157 times higher than that of the indoor locations (0.0007 [0.0001, 0.001]). Considerable locational, diurnal and seasonal variation was observed in the distribution of the median SPD value, with the highest value being recorded in the 'open playground' (0.27 [0.21, 0.28]) followed by 'under shade of tree' (0.083 [0.074, 0.09]), 'canopy' (0.014 [0.012, 0.015]) and 'room with multiple windows' (0.023 [0.015, 0.028]). The relative percentage composition of short, middle and long wavelengths was similar in both the outdoor and indoor locations, with the proportion of middle wavelengths significantly higher (p< 0.01) than short and long wavelengths in all the locations, except 'canopy'. Irrespective of variation in SPD values with location, time, day and season, outdoor locations always exhibited significantly higher spectral power than indoor locations. The relative percentage composition of short, middle and long wavelengths of light was similar across all locations. These findings establish a foundation for future research to understand the relationship between spectral power and the development of myopia.

PurposeConsidering that time spent outdoors is protective for myopia, we investigated how ambient light levels reaching the eye varies across 9 outdoor and 4 indoor locations in 5 different environmental conditions.MethodsIlluminance (lux) was recorded using a lux meter under conditions of weather (sunny/cloudy), time of a day (7:00,10:00,13:00, and 16:00 hours), seasons (summer/winter), and sun protection (hat and cap) in outdoor and indoor locations. Nine outdoor locations were “open playground”, “under a translucent artificial-shade”, “under a porch facing east”, “under a porch facing south”, “under a big tree”, “between three buildings”, “within 4 buildings”, and “canopy”. As a ninth outdoor location, “Under a glass bowl” in the outdoor location was used as a simulation for “glass classroom model” and measurement was taken at the floor level only to determine in overall the illuminance conditions with glass covered on all sides. The 4 indoor locations included “room with multiple large windows”, “room with combination light source”, “room with multiple artificial lights”, and “room with single artificial light”.ResultsThe overall median illuminance level (median; Q1-Q3) recorded in 9 outdoor locations was 8 times higher than that of all indoor locations (1175;197–5400 lux vs. 179;50–333 lux). Highest illuminance in outdoor locations was recorded in “open playground” (9300;4100–16825 lux), followed by “under a translucent artificial shade (8180;4200–13300 lux) and the lowest in “within 4 buildings” (11;6–20 lux). Illuminance under ‘Canopy’, ‘between three buildings’ and ‘within four buildings’ was similar to that of indoor locations (<1000 lux). Time of the day, weather, season, sensor position and using sun protection did not alter illuminance to change from high to low level (>1000 to <1000 lux). Among indoor locations, illuminance in “room with multiple large windows” crossed 1000 lux at a specific time points on both sunny and cloudy days.ConclusionsIlluminance levels in outdoors and indoors varied with location type, but not with other conditions. Given the variation in illuminance in different locations, and the impact it may have on myopia control, appropriate detailed recommendations seems necessary while suggesting time outdoors as an anti-myopia strategy to ensure desired outcomes.

A cross sectional study on mosquito fauna of Anambra East Local Government Area was carried out between June 2017 and August 2018. Pyrethrum knockdown and Human Landing Catch Collection methods were used to collect adult mosquitoes from indoor and outdoor locations respectively, in four randomly selected towns in the LGA. The mosquitoes were identified using standard taxonomic keys. A total of 681 adult mosquitoes were collected: 182 (26.7%) in Aguleri, 135 (19.8%) in Umuleri, 273 (40.1%) in Igbariam and 91 (13.4%) in Nando. Out of these, 551 (80.9%) mosquitoes were collected from indoor location and 130 (19.1%) mosquitoes from outdoor location (P < 0.05). Six (6) Genera of mosquito collected were: Anopheles (39.4%), Aedes (3.7%), Culex (37.9%), Mansonia (18.4%), Eretmapodite (0.6%), and Coquilletidia (0.15%) (P < 0.05). Only Culex mosquitoes showed significant difference in indoor abundance, 43.6% and outdoor abundance 13.8% (P < 0.05). Sixteen species of mosquitoes were identified. The most abundant species of mosquito was Cx. quinquefasciatus, with 35.9% abundance and the least were Coquellettidia species and Cx. annuloris, 0.15% abundance each (P < 0.05). The most abundant Species of mosquito in indoor location was Anopheles gambiae s. l, with 42.3% abundance and the least were Ae. albopictus and Cx. annuloris, with 0.2% abundance each (P < 0.05). The most abundant species of mosquito in the outdoor locations was Mansonia uniformis, with 34.6% abundance and the least were An. funestus and Coquellettidia, with 0.80% abundance (P < 0.05). The presence of the different mosquito species found in this study area is of great medical importance. Most of the species are already known vectors of disease pathogens. Therefore, personal protection, provision of adequate mosquito management options, regular surveillance, and public health sensitizations are hereby recommended.

Given the agonistic nature of near work to promote axial elongation and the antagonistic nature of time outdoors to prevent myopia, we aimed to investigate the following: (a) how the short-term effect of near work performed outdoors (Experiment 1) influences axial length and (b) how near work performed in two different dioptric profiles (uncluttered and cluttered) alters the changes in central axial length (Experiment 2). Forty-six adults (age range: 19-32 years) participated in the study. In Experiment 1, 22 participants completed a 15-min distance task and a reading task in both the outdoor (~30,000 lux) and indoor (~70 lux) locations. In Experiment 2, 24participants performed the same reading task at a study desk in uncluttered and cluttered reading environments. Pre- and post-task ocular biometry measurements were performed for each session using a non-contact biometer. In Experiment 1, a significant increase in axial length from baseline was found after performing reading tasks in both outdoor (mean ± SEM: +12.3± 3.4μm, p= 0.001) and indoor locations (+11.9± 3.1μm, p= 0.001). In Experiment 2, axial length increased significantly from baseline to post reading task, in both uncluttered (+17.9± 3.5μm, p< 0.001) and cluttered reading environments (+19.2± 2.9μm, p< 0.001). No significant changes in axial length were observed either between outdoor and indoor locations (p= 0.92) or between the uncluttered and cluttered reading environment (p= 0.75). Independent of light intensity (outdoor or indoor location) and dioptric profile of the near-work environment (uncluttered or cluttered), a 15-min reading task led to a significant increase in axial length. While the long-term effects of these findings need to be evaluated, practitioners should emphasise how near work can reduce the beneficial effects of time outdoors, while providing recommendations related to time outdoors for myopia control.

Bangladesh is one of the highest tobacco-consuming countries in the world, with a large number of adult users of a variety of smoked and/or smokeless tobacco products. Bangladesh tobacco control act prohibits smoking in public places and requires the owners of public places to display 'no smoking' signages. The objective of this study was to assess the level of compliance with the tobacco control act (smoke-free laws) in public places in a northeast city of Bangladesh. This cross-sectional study was conducted between June 1 and August 25, 2020, across 673 public places in Sylhet city, Bangladesh. The data was collected using a structured observational checklist that included variables such as the presence of active smoking, the presence of designated smoking areas, the display of 'no smoking' signages, evidence of recent smoking such as ashes, butts/bidi ends, and the presence of smoking aids. Among 673 public places, a total of 635 indoor locations and 313 outdoor locations were observed. Only 70 (11%) indoor locations were found to be in good compliance, and 388 (61.1%) indoor locations were found to be in moderate compliance with smoke-free laws. On the other hand, only 5 (1.6%) outdoor locations were in good compliance, and 63 (20.1%) outdoor locations were in moderate compliance with smoke-free laws. The overall compliance with smoke-free laws at indoor locations was 52.7%, and at outdoor locations was 26.5%. The highest compliance was observed at healthcare facilities (58.6%) and the least at transit points (35.7%) for indoor locations. In outdoor locations, the highest compliance was observed at offices and workplaces (37.1%) and the least at transit points (2.2%). Higher active smoking was observed in public places where there was an absence of 'no smoking' signage and the presence of points of sale (POSs) (p-value <0.05). Further, higher active smoking was observed in places where any smoking aids, cigarette butts, bidi ends, or ashes were present (p-value <0.05). This study found moderate compliance at indoor locations and very low compliance at outdoor locations. The government should focus more on implementing smoke-free laws in all kinds of public places, particularly at most frequently visited places and transit sites. 'No smoking' signages should be displayed per legislation across all public places. Policymakers should consider the prohibition of POS in/around a public place as it has a positive effect on smoking.

BackgroundBangladesh is one of the highest tobacco-consuming countries in the world, with a large number of adult users of a variety of smoked and/or smokeless tobacco products. Bangladesh tobacco control act prohibits smoking in public places and requires the owners of public places to display ‘no smoking’ signages.ObjectivesThe objective of this study was to assess the level of compliance with the tobacco control act (smoke-free laws) in public places in a northeast city of Bangladesh.MethodsThis cross-sectional study was conducted between June 1 and August 25, 2020, across 673 public places in Sylhet city, Bangladesh. The data was collected using a structured observational checklist that included variables such as the presence of active smoking, the presence of designated smoking areas, the display of ’no smoking’ signages, evidence of recent smoking such as ashes, butts/bidi ends, and the presence of smoking aids.ResultsAmong 673 public places, a total of 635 indoor locations and 313 outdoor locations were observed. Only 70 (11%) indoor locations were found to be in good compliance, and 388 (61.1%) indoor locations were found to be in moderate compliance with smoke-free laws. On the other hand, only 5 (1.6%) outdoor locations were in good compliance, and 63 (20.1%) outdoor locations were in moderate compliance with smoke-free laws. The overall compliance with smoke-free laws at indoor locations was 52.7%, and at outdoor locations was 26.5%. The highest compliance was observed at healthcare facilities (58.6%) and the least at transit points (35.7%) for indoor locations. In outdoor locations, the highest compliance was observed at offices and workplaces (37.1%) and the least at transit points (2.2%). Higher active smoking was observed in public places where there was an absence of ‘no smoking’ signage and the presence of points of sale (POSs) (p-value <0.05). Further, higher active smoking was observed in places where any smoking aids, cigarette butts, bidi ends, or ashes were present (p-value <0.05).ConclusionThis study found moderate compliance at indoor locations and very low compliance at outdoor locations. The government should focus more on implementing smoke-free laws in all kinds of public places, particularly at most frequently visited places and transit sites. ‘No smoking’ signages should be displayed per legislation across all public places. Policymakers should consider the prohibition of POS in/around a public place as it has a positive effect on smoking.

Editor's evaluation: Disentangling the rhythms of human activity in the built environment for airborne transmission risk: An analysis of large-scale mobility data

Decision letter: Disentangling the rhythms of human activity in the built environment for airborne transmission risk: An analysis of large-scale mobility data

7 - Future research for tropical UHI

We made static and personal PM2.5 measurements with a miniature monitor (RTI MicroPEM) to characterise the exposure of women cooking with wood and charcoal in indoor and outdoor locations in rural Malawi, together with measurements of blood pressure and peak expiratory flow rate (PEFR). Mean PM2.5 concentrations of 1338 and 31 µg/m3 were observed 1 m from cookstove locations during cooking with wood and charcoal, respectively. Similarly, mean personal PM2.5 exposures of 706 and 94 µg/m3 were observed during cooking with wood and charcoal, respectively. Personal exposures to PM2.5 in indoor locations were 3.3 and 1.7 times greater than exposures observed in equivalent outdoor locations for wood and charcoal, respectively. Prior to the measured exposure, six out of eight participants had PEFR observations below 80% of their expected (age and height) standardised PEFR. We observed reductions in PEFR for participants cooking with wood in indoor locations. Five out of eight participants reported breathing difficulties, coughing, and eye irritation when cooking with wood but reported that symptoms were less severe when cooking with charcoal. In conclusion, we observed that exposure to PM2.5 was substantially reduced by cooking outdoor with charcoal. As both wood and charcoal fuels are associated with negative environmental and health impacts, the adoption of high-efficiency cookstoves and less polluting sources of energy will be highly beneficial. Cooking outside whenever possible, and minimising the time spent in close proximity to stoves, may be simple interventions that could reduce the risks of exacerbation and progression of respiratory and cardiovascular diseases in Malawi.

<h3>Abstract</h3> Urban heat islands, where temperatures are elevated relative to non-urban surrounds, are near-ubiquitous in cities globally. Yet, the magnitude and form of urban heat islands in the tropics, where heat has a large morbidity and mortality burden, is less well understood, especially for socioeconomically diverse communities such as those living in urban informal settlements. We utilised 29 years of Landsat satellite-derived surface temperature, corroborated by <i>in situ</i> measurements, to provide a detailed spatial and temporal assessment of urban heat islands in Makassar, Indonesia, a city that is representative of rapidly growing urban settlements across the tropics. We did so with explicit consideration of vulnerable communities living informally. Our analysis identified surface urban heat islands of up to 9.2 °C in long-urbanised parts of the city and 6.3 °C in informal settlements, the seasonal patterns of which were driven by change in non-urban areas rather than in urban areas themselves. In recently urbanised areas, the majority of urban heat island increase occurred before areas became 50% urbanised. As tropical cities continue to expand we expect that urban heat islands will develop quickly as land is urbanised, whereas the established heat island in long-urbanised areas will remain stable in response to city expansion. Green and blue space protect some informal settlements from the worst urban heat islands and maintenance of such space will be essential to mitigate the growing heat burden from urban expansion and anthropogenic climate change. We advocate for green space to be prioritised in urban planning, redevelopment and informal settlement upgrading programs, with consideration of the unique environmental and socioeconomic context of tropical cities. <h3>Highlights</h3> Long-term, fine-scale data are essential to understand the dynamics of urban heat Surface heat islands reached 9.2 °C in the urban core, 6.3 °C in informal settlements <i>In situ</i> data support the use of remote sensing for heat island characterisation The majority of heat island growth occurred before land was 50% urbanised Green and blue space can mitigate heat in informal settlements

Chapter 4 - Spatial considerations

During the initial days that followed the explosion and collapse of the World Trade Center (WTC) on September 11, 2001, fourteen bulk samples of settled dusts were collected at locations surrounding the epicenter of the disaster, and analyzed for persistent organic pollutants, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and select organo-chlorine pesticides. The PCBs comprised less than 0.001% by mass in three outdoor samples analyzed, indicating that PCBs were of limited significance in the total settled dust across lower Manhattan. Likewise, organo-chlorine pesticides, were found at low concentrations in the bulk samples. Conversely, the PAHs comprised up to nearly 0.04% by mass of the settled outdoor dust in the six samples. Further size segregation indicated that the PAHs were found in higher concentrations on relatively large particles (10-53 μm). Significant concentrations were also found on fine particles (<2.5 μm), often accounting for ∼0.005 % by mass. Twelve bulk samples of the settled dust were also collected at indoor locations surrounding the epicenter of the disaster. Concentrations of PCBs comprised less than one ppm by mass in the two indoor dust samples. The organochlorine pesticides were found at even lower concentrations in the indoor samples. The PAHs comprised up to 0.04% by mass of the indoor dust in the eleven WTC impacted indoor samples. Comparison of PAH concentration patterns shows that the dusts that settled indoors are chemically similar to dusts found at outdoor locations. Analysis of one sample of indoor dusts collected from a vacuum cleaner of a rehabilitated home shows markedly lower PAH concentrations (< 0.0005 mass %), as well as differing relative contributions for individual compounds. These PAH analyses may be used in identifying dusts of WTC origin at indoor locations, along with ascertaining further needs for cleaning.

Chapter 4 - Spatial Considerations

This paper investigated urban growth and green land cover decrease impacts on Bucharest metropolitan climate. Time series of Landsat TM/ETM/OLI, MODIS Terra/Aqua and NOAA AVHRR thermal infrared data as well as in-situ meteorological data have been used to assess urban land cover– air and land surface temperature interactions over 2000- 2018 period. The air (Ta) and land surface temperature (Ts), key parameters for urban climate study were analyzed in relation with the Normalized Difference Vegetation Index (NDVI) and surface latent heat flux (SLHF) at city level. Based on these parameters, the urban growth, Urban Heat Island (UHI) effect and the relationships of Ts to other biogeophysical parameters have been investigated. Correlation analysis revealed that, at the pixel-scale, Ta and Ts possessed a strong positive correlation with percent impervious surfaces and negative correlation with vegetation abundances at the regional scale, respectively. Was also analyzed UHI phenomenon during extreme heat waves events. Our results suggest that the most intense UHI occurs in day-time in the summer period during heat waves periods. Satellite data in synergy with insitu data revealed a clear land surface temperature contrast between the central, median and peripheral zones of Bucharest metropolitan zone in Romania. The analysis shows that different urban/periurban zones and landscapes bring diurnally and seasonally different contributions to the local and regional thermal environment. Urban land cover was the most important contributor to increases in regional Ts. Vegetation had a clear cooling effect as the normalized vegetation difference index (NDVI) increased during summer periods.