Explanation: Compressed Natural Gas (CNG) is a cleaner alternative to traditional fossil fuels like diesel and petrol. It is primarily composed of methane and is stored under high pressure. CNG is considered an environmentally friendly fuel because it produces fewer emissions compared to diesel and petrol, making it a preferred choice for reducing air pollution in urban areas.
Delhi, the capital city of India, has been a pioneer in the use of CNG for transport vehicles. The city's initiative to switch to CNG was a significant step in its efforts to combat air pollution. The decision to use CNG was driven by the severe air quality issues that Delhi faced, which were largely attributed to vehicular emissions. By mandating the use of CNG in public transport vehicles such as buses and taxis, the Delhi government aimed to reduce the overall pollution levels in the city.
The implementation of CNG in Delhi's transport system began in the late 1990s and early 2000s. This move was part of a broader strategy to improve air quality and reduce the city's carbon footprint. The use of CNG has been particularly effective in reducing particulate matter and other harmful pollutants that contribute to smog and respiratory issues.
While other major cities in India, such as Mumbai, Kolkata, and Chennai, have also taken steps to reduce pollution, they have not been as prominent in the use of CNG for transport vehicles as Delhi. Mumbai, for instance, has focused more on the introduction of electric buses and the expansion of its metro system. Kolkata has primarily focused on other initiatives to reduce pollution, including the use of electric vehicles and the expansion of its public transport network. Chennai has also not widely adopted CNG in transport vehicles, instead focusing on the promotion of electric vehicles and the improvement of public transport infrastructure.
In conclusion, Delhi stands out as a leader in the use of CNG for transport vehicles, making it the correct answer to the question. The city's initiative to switch to CNG has been a significant part of its environmental policy and has contributed to efforts to improve air quality in the region.