Farmers in Punjab and Haryana are burning stubble at night to evade detection by satellite and local officials working overtime to contain farm fires that have poisoned the air in Delhi NCR, it is learnt. According to official data, incidents of farm fires have reduced this year. Between September 15 and November 7 this year, nearly 21,000 farm fires have been reported in Punjab. This is a drop of about 30 per cent when compared to the same period last year. The numbers, however, do not add up when seen against the number of paddy farmers. For example, over 56,000 farmers harvested paddy in Punjab's Ludhiana but less than a 1,000 farm fires were reported. This indicates that many farm fires incidents are going undetected.