I want to know the answer to the following question:
What method was introduced in December 2015 to reduce New Delhi's air pollution?
All the background I'm provided with is that "In an attempt to curb air pollution in New Delhi, which gets worst during the winter, a temporary alternate-day travel scheme for cars using the odd- and even-numbered license plates system was announced by Delhi government in December 2015.". Is that enough to answer the question?