Housing is the conjunction of the dwelling, the home, the immediate environment and the community. Between 1960 and 1980, the urban population in developing countries more than doubled and is expected to reach 56% of the total population by the year 2025. In many cities, the development of squatter settlements and shanty towns had grown rapidly causing the destruction of green areas. The number of people living in urban slums and shanty towns is an indicator of conditions in the cities and the United Nations had estimated that about one-third of urban dwellers in developing countries live in such settlements. Poverty is highly prevalent among the residents of these areas. Outdoor environmental degradation, together with the social degradation affects the health of the urban population especially the poor causing a burden of ill-health, disability, poor indoor housing, and high maternal and infant mortality. The aim of the present study is to evaluate the indoor and outdoor environment using a simple method and to assess its reliability and validity. The scoring system, which was developed for the assessment of the indoor and outdoor environmental levels included 36 items (18 for the indoor and 18 for the outdoor) using a questionnaire. Results revealed that the proposed scoring system was able to reveal significance difference between served (water, electricity, and sewerage system were available) and unserved areas when using t-test, z-test, and chi-square testing. The proposed scoring system was reliable and valid especially in indoor assessment. Outdoor scores might need more modifications to improve its reliability.