The Delhi government had failed to use more than Rs 1,500 crore in green funds, that it had collected until November 10, despite the capital and other parts of North India battling a severe pollution crisis, PTI reported on Wednesday.

Of these unused funds, Rs 1,003 crore was collected as Environment Compensation Charge, while the rest is mostly made of the cess collected on the sale of diesel. The South Delhi Municipal Corporation collects the Environment Compensation Charge and submits it to the Delhi transport department every Friday, Centre For Science and Environment researcher Usman Nasim was quoted as saying.

Severe smog had enveloped Delhi and several other North Indian cities since November 7. After nearly ten days, Delhi’s air quality improved slightly on Wednesday, a week after it had plummeted to the “severe” category and led to a public health emergency.

The Environment Compensation Charge was imposed by the Supreme Court in 2015 on trucks entering Delhi, while the cess on diesel was announced by the Sheila Dikshit government in December 2007. The funds collected as part of this cess, known as ‘Air Ambience Fund’, is maintained by the Delhi Pollution Control Committee, and currently stands at around Rs 500.

Besides these, the Central Pollution Control Board has also collected Rs 62 crore as 1% cess from the sale of diesel cars with engine capacity of 2,000cc and above in the Delhi and National Capital Region since last August.

It was decided that the funds would be used for “electric mobility”, the news agency quoted a senior transport department official as saying. The funds will be used to subsidise the procurement of electric buses, the official said as they are costly upfront. “Subsequently, running them does not entail much expenditure,” the official said.