Upon conclusion of the 30 years of civil conflict, Sri Lanka has entered into a new era of development. The beautification project of Colombo, Sri Lanka's commercial capital, can be considered as one of the most important projects among urban planning and restoration endeavours implemented throughout the island. In such urban development endeavour, green spaces planning play a crucial role in improving the environmental quality and standard of living of the residents. The objective of this study is to analyse the environmental quality in Colombo city based on green spaces and to provide appropriate recommendations to raise the environmental quality to international standards.

In this study, green space areas were extracted from Thailand Earth Observation System (THEOS) satellite imagery using Normalized Difference Vegetation Index (NDVI). Extracted green space areas were further analysed quantitatively with air quality indicators and population density utilizing deductive indexing method at Grama Niladhari (GN) administrative division level to identify correlations of these factors. An environmental criticality map based on population density and percentage green spaces has been constructed to identify the areas with high criticality. The study revealed that 24% of the entire Colombo Municipal Council (CMC) area consists of green spaces. This study also revealed that 34 GN divisions out of 55 lack the minimum per capita green space recommended by World Health Organization for healthy living. Recommendations are presented regarding regions where new green spaces should be established to enhance the environmental standard of living up to international standards.