Four-year assessment of ambient particulate matter and trace gases in the Delhi-NCR region of India

Research output: Contribution to journalArticlepeer-review


  • Sarkawt M.L. Hama
  • Prashant Kumar
  • Mukesh Khare
  • Sumit Mishra
  • Anil Namdeo
  • Ranjeet Sokhi
  • Paul Goodman
  • Chhemendra Sharma

External organisations

  • Trinity College Dublin
  • Indian Institute of Technology Delhi
  • CSIR-National Physical Laboratory
  • Newcastle University
  • University of Hertfordshire
  • King Abdulaziz University
  • University of Surrey


A key challenge in controlling Delhi's air quality is a lack of clear understanding of the impacts of emissions from the surrounding National Capital Region (NCR). Our objectives are to understand the limitations of publicly available data, its utility to determine pollution sources across Delhi-NCR and establish seasonal profiles of chemically active trace gases. We obtained the spatiotemporal characteristics of daily-averaged particulate matter (PM10 and PM2.5) and trace gases (NOX, O3, SO2, and CO) within a network of 12 air quality monitoring stations located over 2000 km2 across Delhi-NCR from January 2014 to December 2017. The highest concentrations of pollutants, except O3, were found at Anand Vihar compared with lowest at Panchkula. A high homogeneity in PM2.5 was observed among Delhi sites as opposed to a high spatial divergence between Delhi and NCR sites. The bivariate polar plots and k-means clustering showed that PM2.5 and PM10 concentrations are dominated by local sources for all monitoring sites across Delhi-NCR. A consequence of the dominance of local source contributions to measured concentrations, except to one site remote from Delhi, is that it is not possible to evaluate the influence of regional pollution transport upon PM concentrations measured at sites within Delhi and the NCR from concentration measurements alone.


Original languageEnglish
Article number102003
Number of pages18
JournalSustainable Cities and Society
Early online date23 Dec 2019
Publication statusPublished - Mar 2020


  • ASAP-Delhi project, Cluster analysis, Local sources, Megacity Delhi, Polar plots