Assessing the Impact of Urban Green Spaces on Air Quality in Mega Cities

Thesis Abstract

Urban air pollution has emerged as a critical environmental challenge in mega cities, threatening public health, reducing air quality, and exacerbating climate change impacts. Despite increasing urbanization and industrial activities, the capacity of green spaces to mitigate air pollution remains inadequately quantified, necessitating empirical investigations tailored to diverse urban contexts. This study aims to assess the impact of urban green spaces on air quality in mega cities, focusing on quantifying the extent to which urban parks, green corridors, and vegetated rooftops contribute to reductions in key air pollutants, specifically particulate matter (PM10 and PM2.5), nitrogen dioxide (NO2), and ozone (O3). The specific objectives are to (i) characterize the distribution and typology of green spaces within the city; (ii) measure ambient concentrations of selected air pollutants in areas with varying green cover; (iii) analyze the correlation between green space density and pollutant levels; and (iv) evaluate the socio-economic factors influencing green space implementation and air quality outcomes. Employing a cross-sectional quantitative research design, the study draws a stratified random sample of 15 districts within the city, representing different intensities of green space and urban density, with a total sample size of 250 households and 20 urban parks. Data collection involved the deployment of portable air quality sensors over a six-month period to record hourly pollutant levels, complemented by geographic information system (GIS) mapping to quantify green space distribution and land cover changes. The study also utilized structured questionnaires to gather socio-economic data from residents and municipal authorities to understand perceptions and policy influences regarding green spaces. Validity and reliability of the instruments were ensured through pilot testing and adherence to established calibration procedures for air quality sensors. Data analysis integrated descriptive statistics, Pearson correlation coefficients, and multiple regression analysis using SPSS and ArcGIS software packages. The regression models specifically tested the hypothesis that green space density significantly predicts reductions in pollutant concentrations, controlling for traffic density, industrial activity, and meteorological variables. The theoretical framework underpinning this study is rooted in the Biogenic Urban Ecosystem Theory, complemented by the Theory of Environmental Equity, which postulates that equitable distribution of green spaces enhances urban environmental quality and social wellbeing. Expected findings indicate that areas with higher green space coverage demonstrate statistically significant reductions in PM10, PM2.5, and NO2 levels, with a potential mitigating effect on O3 concentrations through vegetative absorption and photochemical interactions. Additionally, the study anticipates revealing socio-economic disparities influencing green space accessibility and implementation, influencing overall air quality improvements. These findings aim to fill existing gaps in empirical evidence concerning specific green space types’ effectiveness and contextual factors affecting such relationships. The study contributes to advancing knowledge on urban environmental management by providing evidence-based insights into the quantifiable effects of green infrastructure on air pollution mitigation in mega cities. It emphasizes the importance of integrating green space planning into urban policy frameworks and offers a methodological blueprint for future research in similar settings. The main conclusion underscores that well-designed and equitably distributed green spaces serve as a vital strategy in improving urban air quality, particularly when complemented by traffic and industrial emissions control. Recommendations include prioritizing the expansion and strategic placement of green spaces, implementing policies that promote urban greening, and fostering community participation in green infrastructure development. Further research is suggested to explore longitudinal impacts, the role of different plant species in pollution absorption, and the socio-economic benefits of green spaces beyond air quality enhancement. This study thereby provides a comprehensive empirical foundation for holistic urban environmental planning aimed at fostering sustainable and healthy urban ecosystems.