Document Type : Research Paper
Authors
1 Associate Professor of Economics, Allameh Tabataba’i University, Tehran , Iran.
2 Professor of Economics, Allameh Tabataba’i University, Tehran , Iran.
3 MA in Environmental Economics, Allameh Tabataba’i University, Tehran , Iran.
Abstract
As societies grow and develop, pollution has emerged as a fundamental management challenge in the contemporary world. This issue holds particular significance in developing countries where economic growth and environmental quality often clash in policy-making. Urban solid waste is a prevalent form of pollution afflicting cities, including Tehran. The pivotal question is whether the production of urban solid waste increases in tandem with citizens' incomes. This article delves into the relationship between the per capita income of Tehran residents and the volume of urban solid waste they generate within the Environmental Kuznets Curve (EKC) framework. Given that household activities directly drive municipal solid waste production, the findings of this study shed light on citizens' environmental preferences. Utilizing panel data from 2007 to 2016 across 22 districts of Tehran, the study confirms that the quadratic model hypothesis of the EKC adequately analyzes this relationship based on Wald's test. Additionally, utilizing the fixed effects method, the study demonstrates the significant impact of per capita income on waste generation. Moreover, the analysis includes population density and household size as control variables, revealing a negative correlation between population density and waste production, while the impact of household size remains statistically insignificant.
Keywords: Solid Urban Waste, EKC, Panel Data, Tehran.
Introduction
The escalating population growth, urbanization expansion, and industrial development witnessed in recent decades have significantly elevated environmental concerns. A paramount issue among these concerns is the discharge of diverse pollutants, posing a pressing challenge for contemporary societies and garnering considerable attention from governmental entities, academia, and researchers. Waste, as a by-product of human endeavors, manifests in various dimensions and necessitates thorough examination. This study delves into the production of municipal solid waste (MSW) and its correlation with citizen income.
The primary focus of this research is to scrutinize the interplay between citizens' income levels and waste generation, particularly waste directly emanating from households. The underlying research hypothesis posits that as citizens' income rises, there is an initial upsurge in consumption and subsequent waste production. However, as per capita income levels advance, it is anticipated that individuals' preferences will undergo a transformation. This evolution is envisaged to manifest as a heightened environmental conscientiousness, leading to a shift towards prioritizing environmental quality and consequently diminishing waste generation.
Literature Review
Within the realm of environmental economics, scholarly attention has been directed towards exploring the intricate relationship between waste generation and per capita income through the lens of the Environmental Kuznets Curve theory. This hypothesis posits an inverted U-shaped association between per capita income and environmental degradation, with a specific focus on urban solid waste within the scope of the present study. Over the recent years, the Environmental Kuznets Curve theory has been employed as a theoretical framework to elucidate the link between per capita income levels and the proliferation of diverse environmental pollutants.
The term "Environmental Kuznets Curve" (EKC) was coined by (Dasgupta and Maler, 1994) owing to the resemblance of this curve to the fundamental Kuznets curve. Subsequently, (Shafik and Bandyopadhyay, 1992) posited, under the assumption of technological stability, consistent consumer preferences, and continued investment in environmental conservation, that escalating economic activities serve as a catalyst for environmental deterioration. Expounding on this notion, (Beckerman, 1992) delineated the presence of evidence showcasing environmental pollution during the early stages of economic advancement. Ultimately, Beckerman advocated for the augmentation of societal income as the paramount and most effective strategy to safeguard and ameliorate the environment.
Methodology
The focal point of this study revolves around the interplay between the income levels of Tehran's residents and the volume of solid waste generated by them. Urban solid waste emanates directly from household sources or urban establishments, indicative of the significant influence citizens possess over the production of this particular form of pollution. This investigation draws upon panel data encompassing 22 districts within Tehran. Specifically, the study incorporates data from the 22 districts under the purview of Tehran Metropolitan Municipality over a temporal span stretching from the year 2006 to 2016, totaling a duration of 10 years. The principal dependent variable under scrutiny pertains to the per capita quantity of waste generated by individuals, with this data sourced from official statistics released by the Municipality of Tehran through the Information and Communication Technology Organization.
Results
To initiate the model estimation process, the F-Limer's test was employed to ascertain the distinct impacts of individual sections. The test results unequivocally rejected the null hypothesis with complete certainty, signifying the inadequacy of assuming uniform origins across all regions. Consequently, the data conveys a nuanced perspective by embracing the notion of unique regional effects as opposed to a homogeneous data distribution. Subsequently, the Hausman test was utilized to discern the most appropriate estimation method between fixed effects and random effects.
Upon a thorough examination of the statistical values within the table and the associated probabilities, it was determined that the random effect estimator should be disregarded with a probability exceeding 95%, thereby endorsing the utilization of the fixed effects method. Subsequently, the quadratic model was estimated employing the fixed effects approach.
The estimated coefficients for the variables exhibit significance, barring the household dimension variable. Remarkably, the coefficient of the squared per capita income variable is not only negative but also statistically significant, underscoring the presence of an inverse U-shaped correlation between per capita income and urban solid waste production. This observation aligns with the Environmental Kuznets Curve (EKC) hypothesis, indicating that as the income of citizens in the 22 districts of Tehran rises, the initial surge in solid waste generation eventually plateaus and diminishes beyond a certain threshold. Moreover, the estimated coefficient for population density displays a negative and statistically significant relationship with urban solid waste production, elucidating that heightened population density inversely correlates with the amount of solid waste yielded by inhabitants.
Discussion
In specific districts within Tehran, the initiation of efforts to diminish urban waste generation has been spurred by income escalations, while in alternate areas; a decline in waste output is projected to transpire once a particular threshold of per capita income is reached. It is imperative to emphasize that these outcomes should not be construed to imply a passive reliance on income augmentation alone to address urban waste management issues, thereby underscoring the continued significance of espousing efficient policies within this domain.
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