Updated: October 13, 2021 2:18:59 pm
Delhi’s air quality has dipped over the past week, going by data from the Central Pollution Control Board (CPCB). Stubble burning, meanwhile, appears to have begun over parts of Punjab and Haryana, going by fire spots mapped by NASA. However, data from Visible Infrared Imaging Radiometer Suite (VIIRS) show less number of fires this year in Punjab and Haryana compared to the same period over the last five years, indicating a delayed stubble burning season.
The air quality index (AQI), calculated using the data from CPCB’s 37 monitoring stations in Delhi, on October 12 stood at 179, which is in the ‘moderate’ category. An AQI that is ‘moderate,’ ranging from 101 to 200, indicates that it could have possible impacts, including breathing difficulties for people with lung and heart diseases.
Pawan Gupta, senior scientist, Earth Sciences at the Universities Space Research Association, NASA Marshall Space Flight Centre, USA, said: “Initial fires typically start near the Amritsar district in early September. The exact start date changes from year to year and depends on many factors including weather.”
As per VIIRS data, On October 11 this year, the cumulative fire count in Haryana was 442. The corresponding figure was 750 in 2020, 723 in 2019, 619 in 2018, 988 in 2017 and 1,095 in 2016, going by VIIRS data provided by Gupta. In Punjab, the cumulative fire count on October 11 this year was 918, compared to 2,996 in 2020, 869 in 2019, 529 in 2018 and 1,392 in 2017.
The AQI appears to have crossed 125 from October 7 onwards, rising continuously thereafter. The last day when Delhi saw air quality in the ‘satisfactory’ category was October 4, when the AQI stood at 91. The AQI recorded in October is in sharp contrast with the AQI for the last ten days of September. From September 20 to September 26, the AQI was in the ‘satisfactory’ category, remaining well below 100. It rose to 120 on September 28 and fell again to 84 on September 30.
NASA’s Fire Information for Resource Management System (FIRMS) shows a cluster of red dots in the northern part of Punjab and another in the northwestern part of Haryana (around Kurukshetra and Karnal), indicating fire spots mapped by the Visible Infrared Imaging Radiometer Suite (VIIRS – an instrument onboard the Suomi NPP and NOAA-20 satellites) over the last 24 hours.
Data from the past few years indicate that Sangrur, Bathinda, Firozpur, Patiala, and Moga see the highest number of fires in Punjab, while Fatehabad, Kaithal, Karnal, Jind, and Ambala in Haryana see the highest numbers, Gupta said.
On the satellite data, Gupta said: “The fire count from satellites is an indication of the number of satellite pixels which detected the fires. Each satellite fire pixel can represent one single fire or many smaller fires, and similarly, one big fire can be seen as many fire counts in satellite data. It depends on satellite resolution and fire size.”
Compared to fire dots mapped on October 1, the number of dots has increased on October 12, the map shows, showing more intense red clusters in parts of Punjab and Haryana on Tuesday.
In the last week of September, on September 28 for instance, the number of red dots was even fewer with just one cluster in the northern part of Punjab and a few scattered dots across Punjab and Haryana.
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