Effect of the creation of a comfortable urban environment for the accumulation of population - Osaka city as a case study

Basic Resources of the Global Environment

Since ancient times, the global environment has been comprised of four elements; the three elements of air, water and soil, plus sunlight from outer space. Based on these four elements, living organisms capable of photosynthesis were generated, and advanced their phyletic speciation over centuries, before the global environment reached its present state comprised of diverse organisms. Humans are one such living organism and nothing more, however, what largely separates us from other animals and plants is the fact that we acquired an intellectual activity, the source of great thinking. As a result, humans have systematically advanced science and technology through creation of the tools necessary for their living and production [1, 2]. Furthermore, during the course of the dramatic development of science and technology, humankind has raised agrarian, industrial and communications revolutions, while extending them from villages to cities, thereby building today's civilized society.

However, although we have greatly benefited from the resulting convenience of civilization, we have at the same time lost or are about to lose the irreplaceable and diverse blessings of nature. This is what we call the global or urban environmental issues, which are indeed in a critical situation. Among them are the examples which most significantly demonstrate the deprivation of nature in cities that have undergone artificial changes and reform. Despite this, a large number of people reside and work in cities where various sophisticated urban functions are concentrated [3]. The main reasons lie not only in the convenience but also the fact that comfort of the living environment has been enhanced with an improved natural environment in cities. As a result, such greater convenience in the urban environment now not only controls the population outflow from cities but also encourages migration from suburban areas to city centers.

This study, selecting Osaka city, which suffered from the bitter experience of pollution, aimed to empiri-

Проблемы экологии, формирования экологической культуры, науки о земле cally clarify that the city's population, once in decline turned to an increasing trend again, as its natural environment began to show a quantitative and qualitative improvement while recovering its aim to be a Human Environmental City.

Representation of a Comfortable Urban Environment by Environmental Indicators

In cities built following changes and reforms of their natural environment, many people have resided and worked in them while benefitting from the convenience of living and various activities, despite fewer natural elements. However, as society became more mature, citizens' values changed and their focus has shifted from material sufficiency to emotional satisfaction. Against the background of such changes in human consciousness, it is now required to provide a diverse and abundant natural environment in cities, not only convenient transportation and communication systems, and highly advanced urban functions in the areas of commerce and human interchanges. That is to say, a comfortable urban environment is necessary for today's cities. In response, quantitative and qualitative expansion and improvement of natural environmental elements remaining in cities, represented by air, water and greenery are carried out while focusing on the creation of a comfortable living and working space.

In order to create a comfortable urban environment, a substantial amount of investment is required, while at the same time one has to demonstrate its benefit. The use of environmental indicators is one of the methods to verify such return on investment [4, 5]. Originating from the social indicator, the environmental indicator is now utilized to understand and predict the present and future status of the environment including nature and living. Today the concept of indicators has spread throughout various fields such as medicine and welfare, in addition to the environmental field, where effective indicators have been developed [6, 7].

Therefore this study also attempted to apply environmental indicators to the creation of a comfortable urban environment.

Application of Environmental Indicators for Creation of a ComfortableUrban Environment

As environmental indicators were applied, this study selected Osaka City as a case study and verified the effectiveness of such indicators, while clarifying accumulation of the urban population resulting from the creation of a comfortable urban environment.

As mentioned above, natural elements remaining in cities are air, water and greenery, and the environmental indicators which represent these elements were considered as follows. As for air, focusing on its quality, carbon dioxide was chosen as a major environmental indicator, which is generated from domestic and production activities, and the combustion of automotive fuel. As for water, again focusing on its quality, biological oxygen demand (BOD) was chosen as a major environmental indicator which measures the natural purifying power of sewage, likewise resulting from the use by domestic and production activities. Regarding water, the presence of which mitigates human mental stress and river water surfaces as its extension were also chosen as an environmental indicator. As for greenery, parks and other green spaces were chosen as a representative environmental indicator, focusing on green spaces in consideration that such urban spaces provide relaxation and peace.

Table 1 shows the results of application based on these concepts and the introduction of representative environmental indicators to Osaka City. In order to clear-

Table 1. Representative environmental indicators for a comfortable urban environment in Osaka City

Note 1: Prepared by the author based on Osaka City Statistics Report.

Note 2: Air and water quality measurements are the average of all measured points.

Note 3: ppm: parts per million.

ly show changes in the urban environment, each indicator was selected at three periods with intervals of ten years and compared with the base year. The table revealed the following:

In Osaka City, air quality has improved significantly with the pollution level being reduced by half in 2016, compared with that of 1996, a period of just 20 years. As for water quality, it has improved dramatically with the pollution level being reduced to one third over the same 20 years. The water area has increased slightly, despite the constraint on urban space resulting from development. On the contrary however, the green spaces have decreased slightly, which is likely due to the exploitation of urban space.

Viewing changes in the urban environment in the case of Osaka City from the perspective of the movement of environmental indicators, the city's effort to create a comfortable urban environment aiming to restore humanity appears to be gradually bearing fruit.

Effect of the Creation of a Comfortable Urban Environment for the Accumulation of Population

It was demonstrated that the outcome of the creation of a comfortable urban environment, although not necessarily sufficient, can be represented by the use of representative environmental indicators. Now, it is necessary to establish the effectiveness of the creation of a comfortable urban environment. This section demonstrates the effect as seen in the accumulation of population in the city. To this end, the population change in Osaka City was examined at three periods with intervals of ten years as in the case of environmental indicators, the results of which are as shown in Table 2. It shows that the total population of Osaka City has increased slightly in 2016 compared with 1996, a period of just 20 years. However, when looking at the central three wards; Kita-ku, Chuo-ku and Nishi-ku, the population increased greatly by 1.25 times in 2006 and 1.60 times in 2016 compared with 1996. This is due to the effect of the creation of a comfortable urban environment in its entirety as demonstrated by the before mentioned movements of environmental indicators, in addition to the improved convenience in urban living and