With Delhi air quality remaining severe for the fourth consecutive day today, Chief Minister Arvind Kejriwal said the odd-even car rationing scheme may be reintroduced if the need arises. Delhi is facing its worst pollution crisis since Diwali last month. He said that We are taking a number of steps like tree plantation drives and buying 3000 buses etc. We sanctioned one of largest metro phases yesterday. If the need arises, we will implement the Odd-Even scheme. Each individual has to play a role in reducing pollution.