Colombo Metropolitan Area Research Articles

Assessment of the Spatiotemporal Variability of Urban Heat Island Intensity in Colombo Metropolitan Area


 
 
 During the last few decades, the Colombo Metropolitan Area (CMA) has experienced rapid population growth and unplanned urbanization, resulting in the replacement of natural landcover with more impervious surfaces. The primary approach of current study was to determine the gradients of air temperature and assess the spatiotemporal variation of atmospheric urban heat island (AUHI) intensity in the CMA considering a range of rural sites extending in different radial directions from the urban center. A total of sixteen rural observation sites that extend from an urban center in four directions were selected within the CMA, with four sites 3.5 km apart from each other in any direction. The air temperatures at each site were measured using HOBO UX-100-003 temperature data loggers for an 8-day period from 21st to 28th, of February 2022. The normalized difference vegetation index (NDVI) and normalized difference building index (NDBI) were used to determine the influence of land use/land cover on air temperatures. The results revealed that air temperature had a strong positive correlation with NDBI. Thus, the current study suggests that the impervious surface/s is a significant predictor of air temperature over the study area. The higher air temperatures were observed at the urban center in relation to the selected suburban and rural observation sites. Hence, the current study confirms that AUHI exists within the selected study area over the CMA. It was found that AUHI tends to be present throughout the day in the CMA. However, it becomes strong between 12.00 A.M. and 6.00 A.M and mostly weakens in the late afternoon hours. Furthermore, this study found that the timing and magnitudes of AUHI vary from direction to direction across the study area depending on the site-specific characteristics of the rural observation sites. The current study emphasizes that site-specific land use/land cover characteristics can have a significant impact on the interpretation of UHI study results even within a single metropolitan area. Therefore, taking only one rural site might not be effective in determining the UHI intensity and a range of sites need to be considered (to select from) for in-depth analysis of UHI in any given area. The findings of the current study will provide firsthand knowledge for urban planners to identify future trends in UHI in the CMA and will promote further UHI research in this area.
 Keywords: Rural observation site, Atmospheric urban heat island, Normalized Difference Vegetation Index
 
 

Development of a Driving Cycle to Characterize the Driving Behaviour of Two-wheelers and Threewheelers in Colombo Metropolitan Area

"ENGINEER", established in 1973 by The Institution of Engineers, is a Journal for dissemination of Engineering knowledge, published quarterly.If you are interested in contributing an Original Technical Paper based on research by the author(s) (intended for Section I) or an Original Article of Professional or Technical interest related to Engineering. (Section II) to this journal please go through the publication checklist which can be downloaded from here.Cover DescriptionCover images show a few views of the Maduru Oya reservoir and construction of right bank canal. The Institution of Engineers, Sri Lanka, acknowledges Eng. L.D. Amila Sanjeewa of the Department of Irrigation for providing images and related information of the project.

Status of the Fishery in Mount Lavinia, Colombo, Sri Lanka

Mount Lavina has become popular due to its unique ecological and recreational qualities which is a limited resource within the Colombo Metropolitan Area. But it also consists of a small fisher community. However the scale of this community is still unknown. Therefore this project was initiated to analyze and review the status of the fisher community in the area. The study was conducted for a 4 month period in weekly intervals. Sociological survey was conducted to assess the status of fishery while separate study conducted to identify the Bycatch species of beach seine fishery. According to the results, there were a total 160 fishermen and 60 boats. Four different mesh sizes were used and almost half of the fishermen used 6 mm size. The main targeted species were squids, Caranx spp., Tuna spp., rock fishes and lobsters which depend on the season and the type of the net. According to statistics, the daily salary ranged between Rs.500-15,000. Crew members were paid by the boat owner and it deepened on the amount of catch and fuel prices. For the non-working days crew members rely on other part time jobs. There were three traditional beach seines operated in the area only in specific seasons (September-January). Study identified 52 species caught in the beach seine fishery. Among them, 27 were Bycatch species. Most Bycatch species were puffers, sharks and rays by weight. Most of them were discarded while others were sold to dry fish markets. Moreover turtles and jellyfishes were recorded as non-fish Bycatch. The study is being continued as a long-term by-catch study to evaluate the intensity of the Bycatch in traditional fishery
 Keywords: Bycatch, Caranx species, Beach seine, Sociology survey, Sri Lanka

URBAN RECREATIONAL WATERFRONT DEVELOPMENT PROJECTS: SUSTAINABILITY ASSESSMENT

A waterfront development is a worldwide well-established phenomenon, and Sri Lanka has recently been involved in waterfront development projects, notably recreational waterfront development projects. Therefore, the primary aim of this study is to evaluate the sustainability of urban recreational waterfront development projects in the Colombo metropolitan area. The qualitative research methodology is used, and primary data is gathered through observations and interviews. The structured interviews were conducted using the judgmental sampling technique with nine experts involved in Urban Recreational Water front Development projects in Sri Lanka. The content analysis approach was used to analyze qualitative data. The study presented six environmental aspects, three economic aspects, and seven social features that contribute to the long-term viability of urban recreational waterfront development projects in Sri Lanka. Accordingly, the study addresses a vacuum in the literature by outlining the social, economic, and environmental factors specific to urban recreational waterfront development projects in Sri Lanka for which there are no prior evidences.
 Keywords: Urban Recreation, Waterfront Development

Analysis on the Road Traffic Congestion in Colombo Metropolitan Area

The main focus of this study is aimed at understanding the factors causing traffic congestion in Colombo Metropolitan Area. Therefore, the study was carried out to address major research questions as, what factors affecting the current vehicle traffic flow, followed by what are the impacts of traffic congestion and what is the opportunity cost of time and fuel wastage cost of congestion. The main objective of the research was to identify the factors affecting the current vehicle traffic flow in Colombo, while the specific objectives of the research are to identify the impacts of traffic congestion, to estimate the opportunity cost of time and fuel wastage cost and to identify whether the commuters are satisfied with the strategies implemented by the government to mitigate traffic congestion. Accordingly, from the survey conducted for the commuters, the researcher identified factors such as “Growth of population and vehicles”, “Unforeseen circumstances”, “Events and incidents” has an individual effect on the current vehicle traffic flow. In addition to that the researcher identified the main impacts of traffic congestion as “Time”, “Fuel”, “Earnings” and “Productivity”. And also the esearcher identified that majority of the commuters are satisfied with the Bus Priority Lane and Park and Ride, while majority of the commuters neither satisfied nor dissatisfied with the Ferry Service as a strategy implemented to mitigate traffic congestion.

Neighborhood dynamics of urban expansion based on morphological spatial pattern analysis and geospatial techniques: a case study of the Colombo metropolitan area, Sri Lanka

ABSTRACT This study examined neighborhood dynamics of urban expansion based on morphological spatial pattern analysis (MSPA) and geospatial techniques in the Colombo Metropolitan Area (CMA) of Sri Lanka from 1992 to 2014. Traditionally, urban expansion has been detected using absolute land use/cover (LULC) terms and landscape patterns (i.e. urban and non-urban). However, non-traditional characterization of urban expansion with neighborhood rules provides a better understanding of urban transformation which is essential to urban planners and managers. This study therefore used MSPA of Landsat images (1992, 2001 and 2014) to classify and detect the expansion of urban land uses based on neighborhood rules. Urban expansion intensity and topologies (infill, extension, and leapfrog) were also employed for further analysis. The results show that the CMA experienced rapid urban expansion, recording a 288% increase in the total urban footprint from 1992 to 2014. The annual urban expansion intensity was higher during the 2000s (1.45%) than during the 1990s (0.95%). Urban expansion topological analysis revealed that leapfrog was the most dominant pattern throughout the study’s temporal extent. An outward infill expansion from the city center was observed, while urban extension exhibited a ribbon-type development along the main transport corridors and coastal belts. The patterns and intensity of urban expansion in the CMA are directly linked to the economic, demographics, and political changes in Sri Lanka. Overall, the study provides an improved understanding of urban expansion in the CMA and offers directions that could be considered in future urban planning initiatives.

The impact of the public library as a children’s reading resource

Aim: This study was conducted to assess the public library as a reading resource for children in the Colombo Metropolitan Area, Sri Lanka.Method: The Colombo Public Library, Sri Lanka, was selected as the case study, and the survey method was used in this research. The study population was children under 14 years attached to the Colombo Public Library, Sri Lanka. The population was stratified, and a sample selection criteria ere were nonprobability sampling technique. A questionnaire and structural interviews were utilized for data collection in the survey.Findings: The research revealed that children’s library should be positioned at a point where the children would find easy access to it. A large number of students in grades 7 and 9 were patronized this children library. Most of the students in the schools within the Colombo Metropolitan Area same frequency use the children’s library. The services such as interlibrary loans, documentation, government publications, and audiovisual services are not provided in the children’s library. There are imbalances between the Sinhala, Tamil, and English media in the distribution of library books. Although the number of periodicals is limited, the contents of those periodicals are too advanced for children under 14 years of age in terms of information, intellect, and appreciation. The primary significant drawbacks of the collection of newspapers are that this section of the library does not have Tamil and English medium newspapers for the readers. It is an obstacle to developing moral, social, and educational skills among children.Implications/Novel Contribution: This analysis is expected to be useful for the Colombo Public Library to upgrade library services to young users as promoters of children’s reading habits. The data will also be useful for any library to formulate library development programs and plan new children’s library development schemes for juvenile users.

Urban Growth: From pixel to reality

Abstract. Urban growth is a complex process created through the interaction of human and environmental conditions. The spatial configuration and dynamic process of urban growth is an important topic in contemporary geographical studies (Thapa and Murayama, 2010). However, urban growth pattern recognition is a challengeable task and it has become one of the major fields in Cartography. Since classical era of cartography, several methods have been employed in modelling and urban growth pattern recognition. It shows that there is no agreement among cartographer or any other spatial scientists on how to map the diverse patterns of urban growth.Typical urban theories such as von Thünen’s (1826) bid-rent theory, Burgess’s (1925) concentric zone model, Christaller’s (1933) central place theory, and Hoyt’s (1939) sector model explain the urban structure in different manner. Most of them do not contribute to visualize the urban growth pattern spatiotemporally. Recently, by addressing this limitations, several sophisticated methods are used in urban growth visualization. Among them, morphological spatial pattern analysis (MSPA) is one of emerging raster data analysis methods which allows us to integrate neighbourhood interaction rules in urban growth pattern recognition and visualization. Angel et al. (2010) developed urban land classification (urban, suburban, rural, fringe open space, exterior open space, and rural open space) based on built and non-built land categories and detected three major types of urban growth (infill, extension, and leapfrog). However, developing urban land classifications using binary land use type and recognising only three types of urban growth pattern may be insufficient due to the existence of a higher complexity of urban growth. In such context, the present study introduce a geovisualization approach to map spatial patterns of urban growth using multiple land categories and develops three sub-levels of urban growth pattern for each major urban growth pattern.The entire process of urban growth pattern recognition developed in this study can be summarized into three steps (Figure 1): (1) urban land mapping – Landsat imageries representing two time points (2001 and 2017) were classified into two land categories (built and non-built) and developed into multiple classes using ancillary data, (2) recognizing three major patterns of urban growth (infill, extension, and leapfrog) – the raster overlay method based on neighbourhood interaction rules, (3) development of sublevels of urban growth – major three patterns were further developed and visualized nine urban growth patterns, namely low infill (LI), moderate infill (MI), high infill (HI), low extension (LE), moderate extension (ME), high extension (HE), low leapfrog (LL), moderate leapfrog (ML), and high leapfrog (HL). The developed procedure of this study in urban growth pattern recognition was tested using a case study of Colombo metropolitan area, Sri Lanka.

Urbanization and Its Impacts on Land Surface Temperature in Colombo Metropolitan Area, Sri Lanka, from 1988 to 2016

Urbanization has become one of the most important human activities modifying the Earth’s land surfaces; and its impacts on tropical and subtropical cities (e.g., in South/Southeast Asia) are not fully understood. Colombo; the capital of Sri Lanka; has been urbanized for about 2000 years; due to its strategic position on the east–west sea trade routes. This study aims to investigate the characteristics of urban expansion and its impacts on land surface temperature in Colombo from 1988 to 2016; using a time-series of Landsat images. Urban land cover changes (ULCC) were derived from time-series satellite images with the assistance of machine learning methods. Urban density was selected as a measure of urbanization; derived from both the multi-buffer ring method and a gravity model; which were comparatively adopted to evaluate the impacts of ULCC on the changes in land surface temperature (LST) over the study period. The experimental results indicate that: (1) the urban land cover classification during the study period was conducted with satisfactory accuracy; with more than 80% for the overall accuracy and over 0.73 for the Kappa coefficient; (2) the Colombo Metropolitan Area exhibits a diffusion pattern of urban growth; especially along the west coastal line; from both the multi-buffer ring approach and the gravity model; (3) urban density was identified as having a positive relationship with LST through time; (4) there was a noticeable increase in the mean LST; of 5.24 °C for water surfaces; 5.92 °C for vegetation; 8.62 °C for bare land; and 8.94 °C for urban areas. The results provide a scientific reference for policy makers and urban planners working towards a healthy and sustainable Colombo Metropolitan Area.

The impact of urban green infrastructure as a sustainable approach towards tropical micro-climatic changes and human thermal comfort

Green infrastructures such as living walls are technological solutions to replace the declined greenery at urbanized environment and also reliable applications for thermal regulation in buildings through insulation effect and escalates the energy use efficiency. Thermal comfort and local climate are spatiotemporally variable. The existing research gap should be addressed by evaluating the performance of vertical green walls in tropical condition. In this study, thermal performance, relative humidity (RH) and CO2 concentration were quantified for basic three types of green infrastructures; such as (T1) living walls, (T2) indirect green façades and (T3) direct green façades located in Colombo metropolitan in Sri Lanka. An in-situ experimental study was conducted considering temperatures at 1 m and 0.1 m distance in front of the green walls, inside the foliage, air gap and external wall surface comparatively to adjacent bare wall control. Three case studies per green infrastructure within Colombo metropolitan area were purposively selected. Simultaneously, RH and CO2 concentration at 0.1 m in front of the green and bare walls were measured for the performance quantification. The internal thermal comfort simulation and occupants’ satisfaction questionnaire survey was executed to assess the green infrastructure performances. The study revealed that vertical greenery systems were highly effective on external wall surface temperature reductions at 1100 h–1500 h time zones. T1 and T2 accounted for superior temperature reduction in the range of 1.61 °C–1.72 °C through the façade relative to the distance than T3. Maximum temperature reduction compared to the bare wall control was obtained for the T1 (0.28 °C–8.0 °C) followed by T2 (1.34 °C–7.86 °C) and T3 (1.34 °C–6.64 °C). Averaged RH increment (1.6%–1.81%) and CO2 reduction (0.63%) occurred near green walls at day time compared to control. An average 28 °C simulated indoor temperature circumstantiate the indoor thermal comfort. 58% and 89.5% occupants’ were satisfied with thermal and visual comfort respectively, thus emphasizing façade greening as a sustainable approach on micro climatic changes and human thermal comfort.

An Urban Heat Island Study of the Colombo Metropolitan Area, Sri Lanka, Based on Landsat Data (1997–2017)

One of the major impacts associated with unplanned rapid urban growth is the decrease of urban vegetation, which is often replaced with impervious surfaces such as buildings, parking lots, roads, and pavements. Consequently, as the percentage of impervious surfaces continues to increase at the expense of vegetation cover, surface urban heat island (SUHI) forms and becomes more intense. The Colombo Metropolitan Area (CMA), Sri Lanka, is one of the rapidly urbanizing metropolitan regions in South Asia. In this study, we examined the spatiotemporal variations of land surface temperature (LST) in the CMA in the context of the SUHI phenomenon using Landsat data. More specifically, we examined the relationship of LST with the normalized difference vegetation index (NDVI) and the normalized difference built-up index (NDBI) at three time points (1997, 2007 and 2017). In addition, we also identified environmentally critical areas based on LST and NDVI. We found significant correlations of LST with NDVI (negative) and NDBI (positive) (p < 0.001) across all three time points. Most of the environmentally critical areas are located in the central business district (CBD), near the harbor, across the coastal belt, and along the main transportation network. We recommend that those identified environmentally critical areas be considered in the future urban planning and landscape development of the city. Green spaces can help improve the environmental sustainability of the CMA.

Spatiotemporal Analysis of Urban Growth Using GIS and Remote Sensing: A Case Study of the Colombo Metropolitan Area, Sri Lanka

Understanding urban growth spatiotemporally is important for landscape and urban development planning. In this study, we examined the spatiotemporal pattern of urban growth of the Colombo Metropolitan Area (CMA)—Sri Lanka’s only metropolitan area—from 1992 to 2014 using remote sensing data and GIS techniques. First, we classified three land-use/cover maps of the CMA (i.e., for 1992, 2001, and 2014) using Landsat data. Second, we examined the temporal pattern of urban land changes (ULCs; i.e., land changes from non-built-up to built-up) across two time intervals (1992–2001 and 2001–2014). Third, we examined the spatial pattern of ULCs along the gradients of various driver variables (e.g., distance to roads) and by using spatial metrics. Finally, we predicted the future urban growth of the CMA (2014–2050). Our results revealed that the CMA’s built-up land has increased by 24,711 ha (221%) over the past 22 years (11,165 ha in 1992 to 35,876 ha in 2014), at a rate of 1123 ha per year. The analysis revealed that ULC was more intense or faster during the 2000s (1268 ha per year) than in the 1990s (914 ha per year), coinciding with the trends of population and economic growth. The results also revealed that most of the ULCs in both time intervals occurred in close proximity to roads and schools, while also showing some indications of landscape fragmentation and infill urban development patterns. The ULC modeling revealed that by 2030 and 2050, the CMA’s built-up land will increase to 42,500 ha and 56,000 ha, respectively. Most of these projected gains of built-up land will be along the transport corridors and in proximity to the growth nodes. These findings are important in the context of landscape and urban development planning for the CMA. Overall, this study provides valuable information on the landscape transformation of the CMA, also highlighting some important challenges facing its future sustainable urban development.

APPRAISING THE STRONGLY ASSOCIATED IMPACTS TO CHOOSE THE MODE OF PUBLIC TRANSPORT: A CASE STUDY OF COLOMBO METROPOLITAN AREA IN SRI LANKA

This study examines a model to evaluate the probability of choosing the mode of public transport with finding most significant aspects related to the characteristic of the journey, characteristic of the traveler and the personal behavior of the traveler. The study area was focused on eleven Divisional Secretariat Divisions of the Colombo Metropolitan Area in the Western Province of Sri Lanka. This area has the most economically advanced functions as the commercial capital of Sri Lanka. The current transportation sector in the focusing area has impact of increasing vehicle ownership and serious inadequacies in the road network such as traffic congestions, shortfall of road capacity and low speed level on road. Hence this study attempts to encourage people for the public transport by focusing about their perception related to the mode choice as a solution for the above issues. The results showed that “Number of Earning Members”, “Vehicle Ownership”, ”Education”, “Age”, “Gender”, “Occupation”, “Trip Distance.”, “Trip Time”, “Total Cost” and “Safety” of the mode were the most significant factors for affecting to choose the public transport. The obtained logistic model with the significant variables had the 78.4% of accuracy for the prediction of probability in using public transport.

Laboratory-Enhanced Dengue Sentinel Surveillance in Colombo District, Sri Lanka: 2012-2014

IntroductionDengue has emerged as a significant public health problem in Sri Lanka. Historically surveillance was passive, with mandatory dengue notifications based on clinical diagnosis with only limited laboratory confirmation. To obtain more accurate data on the disease burden of dengue, we set up a laboratory-based enhanced sentinel surveillance system in Colombo District. Here we describe the study design and report our findings of enhanced surveillance in the years 2012–2014.MethodsThree outpatient clinics and three government hospitals in Colombo District that covered most of the Colombo metropolitan area were selected for the sentinel surveillance system. Up to 60 patients per week presenting with an undifferentiated fever were enrolled. Acute blood samples from each patient were tested by dengue specific PCR, NS1 ELISA and IgM ELISA. A sub-set of samples was sent to Duke-NUS Singapore for quality assurance, virus isolation and serotyping. Trained medical research assistants used a standardized case report form to record clinical and epidemiological data. Clinical diagnoses by the clinicians-in-charge were recorded for hospitalized cases.ResultsOf 3,127 febrile cases, 43.6% were PCR and/or NS1 positive for dengue. A high proportion of lab confirmed dengue was observed from inpatients (IPD) (53.9%) compared to outpatient (clinics in hospitals and general practice) (7.6%). Dengue hemorrhagic fever (DHF) was diagnosed in 11% of patients at the time of first contact, and the median day of illness at time of presentation to the sentinel sites was 4. Dengue serotype 1 was responsible for 85% of the cases and serotype 4 for 15%. The sensitivity and specificity of the clinicians’ presumptive diagnosis of dengue was 84% and 34%, respectively.ConclusionDENV-1, and to a lesser degree DENV-4, infection were responsible for a high proportion of febrile illnesses in Colombo in the years 2012 to 2014. Clinicians’ diagnoses were associated with high sensitivity, but laboratory confirmation is required to enhance specificity.

Analysis of Relationship between Land Surface Temperature and Land Use in Colombo Municipal Area in Sri Lanka, Using Geographical Information System and Remote Sensing

The recent climatological studies try to find out the relationship between land surface temperature and land use type. Specially urban and industrial area was selected for that study, as well as this study was done in Colombo Municipal Council (CMC). The CMC area was central industrial and economical area in Sri Lanka. The majority of people travel to the Colombo Metropolitan area daily for their needs. In the present, both developed and developing countries face to global warming. As the developing country in Sri Lanka, industrial and vehicle usage was very high in the city center in Colombo. In that case land surface temperature (LST) increased day by day. The main objective of this study to analyse the LST using Landsat TM, ETM+ and Landsat 8 images. In addition find out the relationship between LST and land use in CMC area. Arc GIS 10.1 and ERDAS 2014 software were used for this study. It was found out the LST range from 22° C to 33° C. Some of the high temperature zones are shown in Fort and Maradana. Generally there was a high building density (commercial and industrial) and traffic density in while the day. In 1987 high temperature was also recorded close to the Fort and Maradana. However, it has gradually increased to the other areas. It was seen that the impact of that LST distributes to the southern part of the CMC. In addition, all the LST of all areas of CMC passed minimum 30° C during the day time. Keywords: Land surface temperature, Remote sensing, Land use, Colombo

Calibrating Metronamica Land Use Simulation Model for Colombo, Sri Lanka

Cellular Automata (CA) urban simulation models are widely used to explore the complexities associated with urban systems due to their simplicity, flexibility and intuitiveness, and particularly because of its ability to incorporate the spatial and temporal dimensions of the processes. This study is placed in a context where the current planning practices in Sri Lanka are in need of such robust methods and versatile techniques to comprehend land uses in rapidly growing urban areas. Metronamica is a broadly used cellular automata based modeling application that is capable of explore such land use dynamics. This paper present the findings of calibrating Metronamica urban simulation model for Colombo Metropolitan area in Sri Lanka. 1987 is taken as the base year of the calibration and 1987-2007 is considered as the calibration period. Eleven cell states are defined in the study while 100m x 100m is taken as the cell size of the model. Calibration results are analyzed through the visual comparison, contingency table and kappa statistics.

EXPLAINING TRAFFIC FLOW PATTERNS USING CENTRALITY MEASURES

This study examines the capability of centrality parameters of the road network to explain and predict traffic flow by types of vehicles. The case study was conducted in Colombo Metropolitan Area, Sri Lanka. Study used four centrality parameters i.e. connectivity, global integration, local integration and choice; and three analysis methods i.e. topological, metric and angular which introduced by space syntax analysis method to compute network centrality of the road network. Findings of this study stress that, (1) human beings perceive the space mostly from geometrical distance (topological and angular distance) in comparison to metric distance. Further to this, it was found that angular distance is more powerful in global level whereas topological distance is more powerful in local level; (2) it is more appropriate to consider the multiple influences from multiple centrality parameters rather being confined to a single best parameter and influence of each parameter varies based on type of vehicles.

Measuring Area-Wide Road Travel Speeds in Urban Areas in Developing Countries - A Case Study in the Colombo Metropolitan Area

Many urban areas in developing countries are experiencing serious traffic congestion. There are several obstacles to overcome in order to implement a travel speed survey (TSS) in these areas such as budget and time, lack of information on road segments, flexible operation of traffic control and relatively high deviation of travel speeds. Taking these obstacles into consideration, the methodology of an affordable and precise TSS with simple procedure can be developed. The methodology is tested with the field observation of the eight month TSS in the Colombo Metropolitan Area. Based on this, guidelines on the sample size of TSS as well as an appropriate method are proposed and discussed. It is understood that the development in methodology and findings can contribute to the practice of transportation planning in urban areas in developing countries.

A relational analysis of acute wheezing and air pollution

Objective To correlate hospital attendance for wheezing treated with nebulizer therapy with pollutant levels recorded in ambient air in Colombo. Setting Emergency treatment unit (ETU) of the Lady Ridgeway Hospital, Colombo. Design A prospective observational case control study. Method Attendance at the ETU for nebulizer therapy was recorded daily for 12 months. ETU attendance for conditions other than wheezing served as controls. The case and control attendance rates were correlated with daily maximum and minimum one hour average levels of sulfur dioxide and oxides of nitrogen in ambient air as measured by the continuous pollution monitor situated in the Fort, Colombo. Results 30,932 children needed nebulizer therapy in the ETU (median daily attendance 85) during the period of 12 months. The control population was 10,100 children (median daily attendance 28). The pattern of pollutant levels and attendance rates for wheezing showed a correlation on a time series. Conclusion Air pollution levels in Colombo correlated significantly with hospital attendance rates for wheezing needing emergency treatment. The highest recorded levels of sulfur dioxide and oxides of nitrogen in ambient air showed a significant correlation with the highest hospital attendance rates, and the lowest pollutant levels with the lowest hospital attendance rates. We conclude that vehicle related pollutants in ambient air in Colombo are affecting the respiratory health of children. _________________________________________ Senior Lecturer in Paediatrics, Faculty of Medicine, Colombo, 2 Scientist, Environmental Division, National Building Research Organization, Colombo, 3 Medical Officer, Lady Ridgeway Hospital, Colombo, 4 Project Assistant, Environmental Division, National Building Research Organisation, Colombo. Introduction Epidemiological data shows a significant increase in childhood asthma throughout the world, in the past three decades 1,2,3,4 . This sharp rise in incidence and prevalence of acute wheezing is believed to be environmental and not genetic in aetiology 5 . Air pollution has been documented to contribute to respiratory disease and wheezing in children and is a public health concern in many cities 6,7,8,9,10,11 . Automotive emissions are considered the major source of air pollution in urban areas 11 . In Sri Lanka, respiratory diseases are the leading cause of hospitalisation in children and the second commonest cause at all ages 12 . The numbers of children needing bronchodilator therapy at the Lady Ridgeway Hospital, Colombo is increasing each year. There has been a steep incline in the vehicle population in Sri Lanka over the last 25 years. The traffic in Colombo grows by 5% each year and it is estimated that 50% or more of the total vehicle fleet of Sri Lanka plies in the Colombo metropolitan area 13 . The exposure of the city dwelling child to automotive air pollution needs attention. We investigated for an association between hospital attendance for episodes of severe wheezing and air pollutant levels in the city.

City Profile: Colombo

Rooted in a history that dates back 1500 years, the concentration of economic activity and infrastructure in Colombo represents an extreme case of urban primacy within the national context of Sri Lanka. Located on the West Coast of the country, the Colombo metropolitan area accommodates a quarter of the country’s 18.6 million population, and is the economic and political core of the country. However, Colombo is a city of extremes. Its modern and well-serviced core stands in stark contrast to the circumstances of more than half of its population, who live in poorly serviced shack and shanty settlements. The proportion of the population living in these areas continues to expand, notwithstanding a history of innovative and participatory approaches to development planning and management. Complicating these development challenges, the potential of the city is undermined by a civil war that has been under way since the early 1980s, taking an immense toll in loss of life, political polarization, and economic opportunity costs. This paper traces Colombo’s historical development, provides a description of contemporary characteristics and challenges faced by the city, and examines the evolution of plans and programmes designed to improve the conditions of low-income settlements in the city.