Ruang Terbuka Hijau (Green Open Space) and Air Pollution Control: Ecological Perspective

By: Harisman
Student of Postgraduate Program of State University of Jakarta, 2010
Department: Population and Environmental Education
Current regulations and enforcement may be far from reaching the requirements for urban clean air management. For instance Government Regulation No. 41/1999 concerning Air Pollution Control imposed several standards: ambient air quality standard, emission standards for industrial activities and motorcycles, and Pollutant Standard Index (PSI) is not strictly enforced. However, to understand the air pollution problem of a country requires an examination of three key tasks that link changes in vehicles, vehicle and transport activity, or vehicle fuel use to total fuel consumption (ADB Sustainable Development Working Paper Series No. 9, December 2009).
Conservatively, the most potential factor affected to the increasing of air pollution from transport sector include: numbers of vehicles, distances, fuel economy, and modal shares (Lee Schipper, Herbert Fabian, and James Leather, 2009). In addition, number of vehicles, specifically in Indonesia is growing rapidly. In 1990, the total number of registered vehicles was 6 million, in 2007 this was 57 million, and in 2030 this is expected to reach 93 million. Two-wheelers are growing fastest and are the largest in number. Passenger cars (14.4%), buses (3.1%), trucks (7.7%) and motorcycles (74.8%) are the main types of transportation in Indonesia. (Indonesia: Air Quality Profile: 2010 Edition).
It is not surprisingly that most transport modes consume fuel to produce energy. Based on the latest data from International Energy Agency (IEA), transport sector contribute 23% of the total carbon dioxide (CO2) emission in the world. (Greenhouse Gases and their Contribution to Global Warming, Pengembangan Environmental Personality Based Leadership: Sebuah Pemikiran, I Made Putrawan, Munas HIPA-PKLHI, 26 Mei, 2010). One study in Jakarta concludes that transportation is the main source of hydrocarbon (HC), carbon monoxide (CO) and nitrogen oxide (NOX).  Accordingly, transport sector contribute significantly to the air pollution problem of a country. If the transport sector is not managed well, the quality of urban air will become worst and then threats the human ecosystem. To cope with the air pollution problem, Ruang Terbuka Hijau (RTH/Green Open Space) can be an alternative.
Simply, ruang terbuka hijau (RTH/Green Open Space) is defined as a tree-planted public places in a city. It has an important role to air pollution control, noise pollution control, slope stabilization and erosion control and enhancement of water infiltration into soil (Lee at all, 2004 cited in Azhari et al, 2010). It is shown that the function of RTH to absorb carbon from transportation contribute significantly to the urban clean air.
Theoretically, the green open space is categorized as an ecosystem, comprising both living (people, shrubs, herbs, animals, microorganisms), and nonliving parts or physical environment (light, moisture, soil, rocks), energy flow from the sun and water and nutrient cycles. (Odum, 1971 and Mary et all cited in Azhari et al, 2010).
In this paper, the writer will examine the theoretical and empirical data for the role of green open space to cope with the urban air pollution based on several ecological-related concepts.
Ecological-related Concepts
Thermodynamics. Energy is defined as the ability to do work. Transportation requires energy to move people or goods from one place to another. The behavior of energy is describe by the following laws: the First law of thermodynamics, or the law of conservation of energy, states that energy may be transformed from one form into another but is neither created nor destroyed. And the second law states that useful energy decreases at each conversion. Simply, there is no efficient system of energy conversion. (Odum, 1971).
In an ecosystem, material in form of carbon (CO2) from fuel-used transportation will be used by the plant for photosynthesis. Higher efficiencies of plant photosynthesis utilizes the fixed energy of their biochemicals, including the second law of thermodynamics “useful energy decreases at each conversion.” (Eblen, 1994). However, the excess of carbon, specifically under the second law of thermodynamics, is evidence that there is no efficient ways to change energy. It is therefore, since the green open space can’t absorb all carbon from the transport, the release of carbon from the change of energy will pollute the urban air, consequently. Under this discussion, at least, the existence of green open space will support the environment to control the condition of air.

Limiting factors. In some ecosystem one essential elements can become important is limiting factors (Manson, 1992). According to Liebig’s Law essential material available in amounts most closely approaching the critical minimum needed would tend to be limiting one. In addition, there are several factors (limiting factors) that limit vegetative ecosystem growth, including temperature, precipitation, sunlight, soil configuration and soil nutrients. In this article, the excess of carbon from transportation will increase the air temperature. Consequently, the temperature will affect the growth of plant in green open space.
Based on the above short definition, it is clear that the green open space has its limiting factor when the amount of carbon from transport approach the final capacity of the space to absorb the carbon. As a result, the growth of plant in green open space will be destructed or slowly grow. However, the green open space still run its function to control air pollution. In addition, the excess of carbon in the air will affect the air temperature and consequently will affect the growth of plant. Simply, the role of green open space will be limited due to its peak capacity to control air pollution. As a result, the excess release of carbon will also pollute the urban air.
Biogeochemical cycle (nitrogen cycle). Simply, the nitrogen cycle is the set of biogeochemical process by which nitrogen undergoes chemical reaction, changes form, and moves through difference reservoirs on earth, including organisms. Further, there are five processes in nitrogen cycle, namely fixation, uptake, mineralization, nitrification and denitrification. (Harrison, 2010).
Nitrogen fixation is the process wherein N2 is converted to ammonium. It is essential because it is the only way that organisms can attain nitrogen directly from the atmosphere. Certain bacteria and family of plants (e.g. beans, peas and clover) are organisms that fix nitrogen through metabolic processes. Moreover, nitrogen uptake occurs by support from bacteria and another soil organism. According to Harrison we are using nitrogen that has been fixed initially by nitrogen fixing bacteria. In relation to the role of RTH, the process in nitrogen cycle is uptake (plant uptake – see Figure 1) Carbon absorbed by the plant will change the form of nitrogen. The resulted nitrogen is then used by other organisms (Harrison, 2010).




Figure 1: The nitrogen cycle. Yellow arrows indicate human sources of nitrogen to the environment. Red arrows indicate microbial transformations of nitrogen. Blue arrows indicate physical forces acting on nitrogen. And green arrows indicate natural, non-microbial processes affecting the form and fate of nitrogen.

From the picture, it is shown that the nitrogen from fossil fuel combustion is absorbed by the plant (nitrogen uptake). It is therefore, the role of plant in green open spaces contribute to the change of nitrogen gasses from the combustion of fuel-driven transportation.
To sum up, it is clear that the green open space is required for air pollution control. However, if the carbon from the transport sector is too much to be absorbed by the plant in the space, the excess of which will still pollute the air. Accordingly, the role of green open space is limited only to the capacity of the plant to absorb the carbon for photosynthesis purposes.
Azhari, Ayu Wazira, Abdul Haqi Ibrahim, Ragunathan Santiagoo, Saiful Azhar Saad, 2010          “Application of Ecological Principles in Protecting the Environment” retrieved from  
Eblen, 1994, “Ecological Pyramid” retrieved from
Harisson, John Arthur, 2010 “The Nitrogen Cycle of Microbes and Men” retrieved from   
Lee Schipper, Herbert Fabian, and James Leather, “Transport and Carbon Dioxide Emissions:       Forecast, Options Analysis, and Evaluation, ADB Sustainable Development Working             Paper Series No. 9 December 2009
Odum, Eugene. Fundamentals of Ecology. Philadelphia: Saunders, 1971.
Clean Air Initiative for Asian Cities (CAI-Asia) Center: Indonesia: Air Quality Profile: 2010        Edition, October, 2010.
Lab. Perencanaan Lanskap Departemen Arsitektur Lanskap Fakultas Pertanian – IPB: Ruang        Terbuka Hijau (RTH) Wilayah Perkotaan, retrieved from