World Development Sustainability 1 (2022) 100015 Contents lists available at ScienceDirect World Development Sustainability journal homepage: www.elsevier.com/locate/wds Effect of transit-oriented development on air quality in neighbourhoods of Delhi Smriti Bhatnagar, Deepty Jain, Kamna Sachdeva TERI School of Advanced Studies, New Delhi, India a r t i c l e i n f o Keywords: Air quality Land use regression Mixed-use planning Transit oriented development index New Delhi a b s t r a c t Air quality index remains an area of concern for India at the national level, provincial (state level) and the municipal level (urban areas). The Indian government is using transit-oriented development TOD based urban design to reduce private vehicle usage [40]. However, there are few studies that explore the nature of the built environment that needs to be developed in line with TOD principles. This study uses two methodologies: the land use regression analysis and the TOD index analysis to ascertain the nature of the built environment in line with TOD policies in the context of New Delhi. Land use regression analysis makes use of urban form indicators for the study neighbourhoods in New Delhi as independent variables. The relationship between these urban form variables and the air quality index is tested. The second methodology creates a composite index by amalgamating the built environment indicators into a single index using the information entropy weighting method. This index proves useful in measuring the ‘TOD-ness’ of the neighbourhoods of New Delhi to ascertain the relationship of TOD with air quality. The results from the study serve as inputs to urban and transport planners. Future urban and regional plans can be developed in line with the results of this study. Introduction The National Government of India and the State government of New Delhi have been trying to tackle the acute problem of air pollution. The government is encouraging the use of public transport in New Delhi [16]. Lately, the Indian Government is altering the built environment in New Delhi, in line with transit-oriented development TOD princi- ples [30]. The National Transit Oriented Development policy of India drafted by the Ministry of Housing and Urban Affairs; Government of India is now an important element of master plans. The policy lays emphasis on developing sustainable urban growth centres and liveable communities. One of the visions of the policy is to curb pollution by making public transport accessible and encouraging people to walk and cycle [30]. It is well established that TOD has the potential to improve air qual- ity by reducing reliance on private vehicles [4,23,24]. Studies conducted in Asian cities have shown the effect of mass transit on the surround- ing environment [23,37,40,41]. However, there are few studies in the Indian context that establish the effect of TOD on air quality [4,16,25]. As per the National Transit Oriented Development policy, the built en- vironment development is being guided by TOD principles. Yet there are few research studies available to ascertain the nature of the built environment in line with TOD. Abbreviations: TOD, Transit-oriented development. E-mail addresses: smritibhatnagar.1987@gmail.com (S. Bhatnagar), archikooldeepty@gmail.com (D. Jain). This study fills in this gap in knowledge and tests two methodolo- gies to measure the extent of TOD and its effect on air quality. The first methodology uses built environment indicators and measures their ef- fect on air quality. Built environment indicators are classified under the following broadheads: lengths of types of roads, areas of types of land uses, of population densities, and distances from amenities. Air qual- ity includes concentrations of air pollutant indicators: nitrogen dioxide (NO2), sulphur dioxide (SO2), particulate matter (PM2.5) and particu- late matter (PM10). Studies of this nature, commonly known as the land use regression studies, have been useful in ascertaining the relationship of the built environment with air quality. Many such studies exist in the Asian context [35,39,42,43]. Results from these studies have been instrumental in guiding built environment development in and around urban areas. The second methodology will create a TOD index from constituent built environment indicators. Index development has been a common methodology in TOD studies [14,17,27,28,31,33]. Using an accumula- tive index for measuring the degree of TOD is more convenient than using more than one distinct built environment indicator. The method- ology of the built environment indicator composition is the information entropy weighting method. The simultaneous usage of these two methods helps in validating the methodology for index creation. There have been studies that have https://doi.org/10.1016/j.wds.2022.100015 Received 25 February 2022; Received in revised form 13 May 2022; Accepted 15 May 2022 2772-655X/© 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)