The levels of NOx during post-CNG period have been observed to be slightly increased with fluctuating trend. The levels of NOx in ambient air depends upon many factors, such as movement of vehicles, operation of generators, thermal power plants, incinerators, etc. These include poor maintenance and performance of catalytic converters and also non-optimized conversion of CNG vehicles leading to higher emissions of NOx from these vehicles, increase in 4-stroke vehicles & private diesel vehicles, gas-based power plants, industrial activities like electroplating and coal-based thermal power plants.
Vehicles being run on fossil fuels would contribute towards NOx emission in smoke due to technical reasons, i.e., burning of fuel in presence of free nitrogen available in ambient air.
As per Supreme Court directives dated May 9, 2002, the four cities that have been identified as equally or more polluted than Delhi were Kolkata, Kanpur, Pune andAhemdabad. The concerned authorities have prepared schemes for switching over to CNG/LPG as automotive fuel in these cities.
The status of CNG vehicles in Delhi is mentioned in table below:
Source: PIB Press Release dated August 24, 2010.
