The persistent fog conditions in northern regions of the Indian subcontinent, including north India, have broken all records since the beginning of daily monitoring of satellite data in 2014. The thick fog layer sometimes engulfs the entire swathe of over 2,500 km from Lahore in Pakistan to Dhaka in Bangladesh. This winter season, the misty conditions/ low cloud cover has lasted for more than a month at a stretch, making it the longest fog spell in a decade.