Delhi Chief Minister Arvind Kejriwal left for Haryana on Wednesday to meet Chief Minister Manohar Lal Khattar and discuss the issue of stubble burning and air pollution.Kejriwal in a tweet said he along with Delhi Environment Minister Imran Hussain, Environment Department Secretary Keshav Chandra was on their way to the neighbouring state "to discuss issues related to pollution" with Kattar and his team.The Delhi Chief Minister had earlier blamed stubble burning by farmers in Punjab and Haryana for the thick smog that has descended over Delhi. He had also written to the Chief Ministers of both states and requested for a joint meeting to "find solution" to the problem that has led to widespread health concerns in the National Capital Region.On Tuesday, Punjab Chief Minister Amarinder Singh rejected Kejriwal's request to meet and instead asked him to refrain from "trying to politicise a serious issue".Singh said that air pollution in NCR was not an inter-state matter and needed the Centre's intervention.Air quality in the National Capital Region saw a marginal improvement from "severe plus" to "severe" on Tuesday.