Amid rising pollution especially in North India due to stubble burning, 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, as reported by NDTV.

Although this year as per official data, incidents of farm fires have reduced. 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.

This could be happening because the daily farm fires count has to be updated by 8 pm. The farmers, aware of this loophole, are setting fire to the fields after 8 pm.

In Haryana, the Haryana Space Applications Centre is using satellite imaging to detect farm fires. This imaging, however, is not conducted round the clock. Dr Sultan Singh, HARSAC director, has told The Tribune that the satellite imaging was carried out at 12-hour intervals.

Some fires, therefore, may slip through the radar.

According to reports, a section of farmers in Haryana believes that burning crop residue after sunset may help them evade detection by satellite. These farmers argue that satellite imaging uses temperature for detection of farm fires incidents, so the drop in temperature at night may lead to the satellite failing to identify farm fires.

Undetected farm fires lead to mismatch in data. This is critical as government authorities are fine-tuning their strategy based on the data.

AAPwhich rules both Punjab and Delhi, has said there has been a huge drop in the incidents of farm fires in Punjab and blamed vehicle emissions in BJP-ruled Uttar Pradesh and Haryana for Delhi's bad air days.

The BJP has hit back, accusing Delhi Chief Minister Arvind Kejriwal of turning the national capital into a "city of smoke".

But whom is to blame?