Amritsar/ Ludhiana (Punjab), New Delhi, Oct 07 (ANI): Defiant farmers in Punjab province said they would continue to burn paddy stubble, challenging a state government ban on burning farm residue aimed at checking air pollution. Farmers burn paddy stubble to clear their fields ahead of the wheat sowing season. They said that they are aware of the consequences but have no other option but to follow the annual ritual of burning the dry straw. Crop stubble burning has caused one-quarter of the air pollution that blanketed Delhi last November, the Ministry of Environment, Forest and Climate Change told parliament in February. The particles from the stubble burning combine with industrial pollution, vehicle exhaust and dust to cover the region every year as winter approaches and wind speeds drop.