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Around 1,000 farm fires were detected in Punjab alone today -- on a day the Supreme Court ripped into the Delhi government over the pollution blanket over north India that went off charts. Hiren Jethva, an aerosol remote sensing scientist at NASA Goddard Space Flight Center, told News Agency this evening that this data was collected by the NASA satellite between noon and 1.30 pm -- a time band that over the last three years has showed a decreasing trend of farm fires.
The farm fires, he reiterated today, are lately lit well after 2 pm, when the NASA satellites have passed over India -- a situation that has raised questions over whether farmers are deliberately attempting to hoodwink the satellite.
"Except today, there has been a clear shift in the burning pattern. Since 2002, most fires took place in the 1 to 2 pm window," which has not been the case over the last three years.
Till lately, he said he was happy to see the downward trend, that his predictions about the number of fires have been way higher than the data on the ground - which only left one fact unexplained - how the pollution levels could be increasing despite the lower numbers. Also, the aerosol content in the air - measured by sensors mounted on satellites - indicate far higher levels of particulate matter associated with pollution.
"Pollution load has increased over the subcontinent - unseen in the last 20 years' data. Aerosol load highest over the last two weeks. Also Look at PM 2.5 data in Delhi was 1000 microgram per metre, that is crazy high, unprecedented," he told News Agency.
Now, thanks to data collected by sensors on a South Korean geo-stationary satellite, it has become clear that the time window for lighting of farm fires may have changed.
In a post on X that showed comparative DATA collected since 2019, he explained the change in trend.
A preliminary quantitative analysis of the GK2A-AMI sensor's 3.8-micron data indicates that fire activity tends to peak in the late afternoon over the past three years @VishnuNews Agency @CBhattacharji @jksmith34 @avoiland @KMA_Skylove_eng pic.twitter.com/oP7zEw17hT
— Hiren Jethva (@hjethva05) November 15, 2024
What the Authorities Say
Prof Adarshpal Vig, the Chairperson of the Punjab Pollution Control Board, however, chose to differ on Mr Jethva's view that farm fires are the "one giant source of pollution in this season".
While he admitted that the data today showed there were 1,251 fires - the largest in the whole season - this does not take into account the seasonal change in weather that tends to trap pollution closer to the ground instead of dissipating it in the atmosphere, as happens in summer.
It also did not do away with the last two year's downward trend, he said. In 2023, there were 33,719 instances of stubble burning, which was 70 per cent down from the previous year, when 48,000-plus farm fires were reported.
Asked why the authorities were not taking into account the fires lit after 2 pm, Prof Vig said, "Nothing like this. I have been telling you the data for previous 3 years and we have been using the same mechanism for past 4 to 5 years. The data comes from the Punjab remote sensing centre located in Ludhiana University Campus and they are taking the data through ISRO and NASA".
"I know that they take thermal images... The heat stays for hours. As Hiren was saying, it will take 375 meters area and there are more than one or two satellites and they do the filtering, since fire from cities may get into the data," he added.
"Fires are on a downtrend in that time band if you look at NASA satellite data, which ISRO also uses since 2022. Fires occurring after that can be seen in the geostationary satellite. The Korean satellite shows a clear increase in the short wave infra-red signal. That data shows there is a clear increase of fires in the late afternoons that we are not counting. But we can see in the aerosol load and the PM 2.5 in Delhi the next day," interjected Mr Jethva.
But the point was hotly debated by Prof Vig. Asked if the overall number of fires are coming down, why not the aerosol loads, he said the authorities are "not measuring the aerosol loads".
"So that is not something I can comment on. We are only looking at the BRSC data. But along with stubble burning, there are other sources of pollution, like vehicular or industrial pollution. So maybe those are not dissipating because of the season change," he added.
Mr Jethva pointed out that those sources constant. "Without stubble burning, no one can explain the rise in pollution," he said.
Prof Vig pointed out that one has to take into account the effects of season change. "Why we are not counting these kind of things?" he said.
In summers, the pollution is the same, but the particulate matter gets dispersed due to the heat and the strong winds.
But in winter, they are "not going out of the atmosphere, making it more visible to everyone and making it more effective to the health issue,' he added.
The Supreme Court's Strictures
Earlier today, the Supreme Court had mentioned the fresh facts brought to light by Mr Jethva, calling it a "very disturbing feature" in its order.
"ISRO is getting data from the NASA satellite which passes over NCR region at around 10.30 am and 1.30 pm daily. Therefore instances of farm fires captured by the satellite are only for those periods. Based on information given by a senior scientist of NASA, learned amicus (senior advocate Aparajita Singh) pointed out that a Korean satellite, which is stationary satellite, has captured the farm fires at 4.20. It is pointed out that there is a difference between data collected by the stationery satellite and data collected by the polar orbiting NASA Satellite," the court said.
"We direct the Union of India and the (CAQM) commission to make immediate arrangements to take data either from the Korean stationary satellite or any other stationary satellite, so that data of farm fires throughout the day can be made available to the state to enable them to take immediate action," the court added in its order.
The judges had pulled up authorities over the delay in implementing tough restrictions under the Graded Response Action Plan (GRAP).
The bench of Justice AS Oka and Justice AG Masih questioned why GRAP 3 was implemented three days after the AQI crossed the 300 mark. When the Centre's counsel replied that they were tracking whether the AQI dips, the court said, "Once it reaches, it has to be invoked... how can the applicability of stage 3 be delayed anyhow... how can you wait for three days?"
"We are making it very clear that you will not go below Stage 4 without our permission now even if AQI goes below 300, that is the order we are proposing," the judges said.
GRAP 4 kicks in when AQI crossed the 450 mark. Commercial vehicles registered outside Delhi are banned from entering the capital unless they are EVs, CNG or they conform to BS-VI norms. Decisions can also be taken on discontinuing physical classes for senior classes too and the odd-even road rationing scheme.