Relationship between urban form and air quality at metropolitan area

Abstract

Air pollution has grown by 8% globally and in India due to air pollution, every year 1.4 million people die a premature death, which accounts for one life after every 23 seconds as per World health organization report 2016. Greenpeace report says that none of the Indian city complied with the WHO air pollution norms. Cities occupies less than 3% of the earth's land surface, yet they produce 78% of anthropogenic pollutants which play a significant role to decline of air quality at local & regional scales (J.Frank,2006). Nagpur is selected as case study area because it is 3rd largest city in Maharashtra which is seen as one of the rapidly developing central India's metro city. It is 13th largest Metropolitan urban area in India with poor air quality but with highest number of monitoring stations and availability of air pollution data for analysis. Seven zones in Nagpur are identified as per the location of monitoring station. While there are many factors that influence the air quality in a settlement, this study is limited only to the assessment of the role of urban form in the declining air quality in a settlement and find out strategies for urban form and land use configuration to improve air quality at local level. For achieving this aim, five prong objectives have been stet as: (a) To Explore means of quantitatively explaining Urban form, (b)To Understand whether any relationship has already been established between form and air quality in urban context, (c) To assess urban form and air quality condition in selected zones of Nagpur, (d) To Evaluate the role of different aspects of urban form influencing air quality. (e) To suggest strategies for urban form changes including land use configuration to improve air quality. Urban form can be studied in different ways but, for the study, concepts of spatial characteristics and land use pattern at neighbourhood level was focused upon. The chosen parameters to quantitatively explain Urban form are: percentages of land use, ground coverage, total floor area, ratio of residential to non-residential floor area, ratio of built area to open area, average land consumption per person, tree cover, traffic volume count and road length. For quantifying air quality, parameters chosen are: ambient Concentration of RSPM, SPM, SO2 and NOx [based on the availability data]. Three locations in Nagpur were selected on the basis of pollutant concentration, ground coverage and open spaces. The area of three locations is 4.3% of total Nagpur area and having cities 3% population. For ascertaining „land use‟, „building use‟, „traffic volume count‟ and „total floor area‟ primary survey was conducted. „Ground coverage‟ and „tree cover‟ was calculated by using satellite data. „Average land consumption per person‟ was calculated based up on population and ground coverage. Traffic volume count was conducted at 12 different locations within study area. Air quality index formula is used for comparative analysis which is given by EPA (Environmental Protection Agency). Analyses reveal strong correlations between „total floor area‟ and „air pollution‟. Study also reveals that parameters, viz. open space, tree cover, mixed land use floor area and ratio of residential to non-residential floor area are negatively correlated; while parameters, viz. land consumption per person, local road length, industrial floor area are positively correlated with pollution. Based on the lessons learnt as above, the study concludes with strategies for future urban development to improve air pollution scenario in terms of desired urban form characteristics and other related possible interventions such as resilient plant identification as part of green infrastructure.