Environmental Monitoring and Assessment

, Volume 115, Issue 1–3, pp 405–417 | Cite as

Assessment of Air Quality After the Implementation of Compressed Natural Gas (CNG) as Fuel in Public Transport in Delhi, India

  • Khaiwal Ravindra
  • Eric Wauters
  • Sushil K. Tyagi
  • Suman Mor
  • René Van Grieken


Public transport in Delhi was amended by the Supreme Court of India to use Compressed Natural Gas (CNG) instead of diesel or petrol. After the implementation of CNG since April 2001, Delhi has the highest fraction of CNG-run public vehicles in the world and most of them were introduced within 20 months. In the present study, the concentrations of various criteria air pollutants (SPM, PM10, CO, SO2 and NOx) and organic pollutants such as benzene, toluene, xylene (BTX) and polycyclic aromatic hydrocarbons (PAHs) were assessed before and after the implementation of CNG. A decreasing trend was found for PAHs, SO2 and CO concentrations, while the NOx level was increased in comparison to those before the implementation of CNG. Further, SPM, PM10, and BTX concentrations showed no significant change after the implementation of CNG. However, the BTX concentration demonstrated a clear relation with the benzene content of gasoline. In addition to the impact of the introduction of CNG the daily variation in PAHs levels was also studied and the PAHs concentrations were observed to be relatively high between 10 pm to 6 am, which gives a proof of a relation with the limited day entry and movement of heavy vehicles in Delhi.


CNG public transport CO NOx SO2 PM10 BTX PAHs principal component analysis 


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  1. Aggarwal, A.: 1999, {Engines of the Devil: Why Dieselisation of Private Automobile Fleet Should be Banned-The Case Study of Delhi}, Centre for Science and Environment, New Delhi. Available at http://www. cseindia.org/campaign/apc/pdf/dieselmo.pdf.
  2. Beer, T., Grant, T., Brown, R., Edwards, J., Nelson, P., Watson, H. and Williams, D.: 2000, ‘Life-cycle Emissions Analysis of Alternative Fuels for Heavy Vehicles’, Report C/0411/1.1/F2, CSIRO Division of Atmospheric Research, Aspendale, Vic., xxi, pp. 125.Google Scholar
  3. Brandon, C. and Homman, K.: 1995, ‘The Cost of Inaction: Valuing the Economic-Wide Cast of Environmental Degradation in India’, Asia Environment Division, World Bank, 17 October 1995.Google Scholar
  4. C.P.C.B.: 1995, ‘Annual Reports 1993/94’, Central Pollution Control Board, Ministry of Environment and Forest, Delhi-32 (www.cpcb.nic.in).
  5. C.P.C.B.: 2002, ‘Parivesh: Benzene in Air and Its Effects on Human Health’, February 2002, Central Pollution Control Board, Ministry of Environment and Forest, Delhi-32, available at www.cpcb.nic.in.
  6. C.P.C.B.: 2003, ‘Parivesh: Polycyclic Aromatic Hydrocarbons (PAHs) in Air and Their Effects on Human Health’, November 2003, Central Pollution Control Board, Ministry of Environment and Forest, Delhi-32, available at http://www.cpcb.delhi.nic.in/ph/ch81103.htm.
  7. C.S.E.: 2001, ‘The Smokescreen of Lies: Myths and Facts about CNG, Right to Clean Air Campaign Team’, Centre for Science and Environment, New Delhi. Available at http://www.cseindia.org/campaign/apc/myths_facts/index_final.htm.
  8. Cotham, W. E. and Bidleman, T. F.: 1995, ‘Polycyclic aromatic hydrocarbons and polychlorinated-biphenyls in air at an urban and rural site near Lake Michigan’, Environ. Sci. Technol. 29, 2782–2789.CrossRefGoogle Scholar
  9. Dursbeck, F., Erlandsson, L. and Weaver, C.: 2001, Status of Implementation of CNG as a Fuel for Urban Buses in Delhi: Findings – Conclusions – Recommendations, Report done for Centre for Science and Environment, New Delhi, May 23. Available at http://www.cseindia.org/campaign/apc/pdf/CNGEXPER.PDF.
  10. Duval, M. M. and Friedlander, S. K.: 1981, ‘{Source Resolution of Polycyclic Aromatic Hydrocarbons in Los Angeles atmosphere – Application of CMB with First Order Decay}’, US EPA Report No EPA-600/2-81-161. Google Scholar
  11. Economic Survey of Delhi: 2003–04, Government of National Capital Territory of Delhi, 6th Level, B-Wing, Delhi Secretariat, I. P. Estate, New Delhi, India. Available at http://delhiplanning.nic.in/.
  12. Fang, G. C., Wu, Y. S., Chen, M. H., Ho, T. T., Huang, S. H. and Rau, J. Y.: 2004, ‘Polycyclic aromatic hydrocarbons study in Taichung, Taiwan, during 2002–2003’, Atmospheric Environ. 38, 3385–3391.CrossRefGoogle Scholar
  13. Fondazione Salvatore Maugeri (F.S.M.).: 2000, Instruction for Volatile Organic (VOCs) Sampling by Radiello and Carbon Disulfide Recovery, Environmental Research Centre, 16-I35127, Padova, SOVchim-UK-398.Google Scholar
  14. Godoi, A. F. L., Ravindra, K., Godoi, R. H. M., Andrade, S. J., Santiago-Silva, M., Van Vaeck, L. and Van Grieken, R.: 2004, ‘Fast Chromatographic determination of polycyclic aromatic hydrocarbon in aerosol samples from sugar cane burning’, Journal of Chromatography A 1027, 49–53.CrossRefGoogle Scholar
  15. Goyal, P. and Sidhartha.: 2003, ‘Present scenario of air quality in Delhi: A case study of CNG implementation’, Atmospheric Environ. 37, 5423–5431.CrossRefGoogle Scholar
  16. Guo, H., Lee, S. C., Ho, K. F., Wang, X. M. and Zou, S. C.: 2003, ‘Particle-associated polycyclic aromatic hydrocarbons in urban air of Hong Kong’, Atmospheric Environ. 37, 5307–5317.CrossRefGoogle Scholar
  17. Gurjar, B. R., van Aardenne, J. A., Lelieveld, J. and Mohan, M.: 2004, ‘Emission estimates and trends (1990–2000) for megacity Delhi and implications’, Atmospheric Environment 38, 5663– 5681.CrossRefGoogle Scholar
  18. Harrison, R. M., Smith, D. J. T. and Luhana, L.: 1996, ‘Source apportionment of atmospheric polycyclic aromatic hydrocarbons collected from an urban location in Birmingham, UK’, Environ. Sci. Technol. 30, 825–832.CrossRefGoogle Scholar
  19. Kavouras, I. G., Koutrakis, P., Tsapakis, M., Lagoudaki, E., Stephanou, E. G., Baer, D. V. and Oyola, P.: 2001, ‘Source apportionment of urban particulate aliphatic and polynuclear aromatic hydrocarbons (PAHs) using multivariate methods’, Environ. Sci. Technol. 35, 2288–2294.CrossRefGoogle Scholar
  20. Khalili, N. R., Scheff, P. A. and Holsen, T. M.: 1995, ‘PAH source fingerprints for coke ovens, diesel and gasoline engines, highway tunnels, and wood combustion emissions’, Atmospheric Environ. 29, 533–542.CrossRefGoogle Scholar
  21. Kumar, P. and Bhattacharya, S.: 1999, ‘When wealth is not health’, Down to Earth 7, 33.Google Scholar
  22. Masclet, P., Mouvier, G. and Nikolaou, K.: 1986, ‘Relative decay index and sources of PAH’, Atmospheric Environ. 20, 439–436.CrossRefGoogle Scholar
  23. NAAQMS series: 1998–2004, {Ambient Air Quality Monitoring Status of Delhi}, Central Pollution Control Board, Delhi-32.Google Scholar
  24. Ravindra, K., Bencs, L., Wauters, E., de Hoog, J., Deutsch, F., Roekens, E., Bleux, N., Bergmans, P. and Van Grieken, R.: 2005, ‘Seasonal and site specific variation in vapor and aerosol phase PAHs over Flanders (Belgium) and their relation with authropogenic activities’, Atmospheric Environment, Doi: 10.1016/j.atmosenv.2005.10.011.Google Scholar
  25. Ravindra, K., Mittal, A. K. and Van Grieken, R.: 2001, ‘Health risk assessment of urban suspended particulate matter with special reference to polycyclic aromatic hydrocarbons: A review’, Rev. Environ. Health 16, 169.Google Scholar
  26. Ravindra, K., Mor, S., Ameena, Kamyotra, J. S. and Kaushik, C. P.: 2003, ‘Variation in spatial pattern of various air pollutants before and during initial rain of monsoon’, Environ. Monit. Assess. 87, 145–153.CrossRefGoogle Scholar
  27. Scientific Review Panel (SRP): 1998, ‘Findings of the Scientific Review Panel on The Report on Diesel Exhaust as Adopted at the Panel's April 22, 1998’, available at www.arb.ca.gov/toxics/dieseltec/de-fnds.htm.
  28. Transport Department: 2004, Government of NCT of Delhi, New Delhi, available at http://transport.delhigovt.nic.in/.

Copyright information

© Springer Science + Business Media, Inc. 2006

Authors and Affiliations

  • Khaiwal Ravindra
    • 1
  • Eric Wauters
    • 2
  • Sushil K. Tyagi
    • 3
  • Suman Mor
    • 4
  • René Van Grieken
    • 1
  1. 1.Micro and Trace Analysis Center, Department of ChemistryUniversity of AntwerpAntwerpBelgium
  2. 2.Flemish Environment Agency (VMM)GentBelgium
  3. 3.Central Pollution Control BoardDelhiIndia
  4. 4.Centre for Energy StudiesIndian Institute of Technology DelhiNew DelhiIndia

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