Summary:
While forest fires always blaze through Uttarakhand around this time of the year, the scale of destruction this time around has been much larger.
Dry conditions because of little post-monsoon rain and no snowfall this winter (Nainital had snowfall six times in the winter of 2019-20) have fed the inferno.
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For days now the forests of Uttarakhand have been on fire, turning the air over the pristine hill state lethal.
Levels of black carbon, or soot, have shot up six times while that of ozone has trebled — both going straight from safe levels to dangerously toxic ones within perhaps a week.
By Friday, black carbon levels had gone from about 1,000-2,000 microgram per cubic metre last month, before the fires started, to 10,000-12,000 microgram per cubic metre of air.
The concentration of ozone, which used to be around 40-45 parts per billion then, has risen to 110-115 parts per billion now.
The safe threshold for black carbon in the air is 3,000-4,000 microgram per cubic metre, while that of ozone is 40-50 parts per billion with an hourly range of 80 and an eight-hour average range of 60.
High black carbon and ozone in the air can cause complications from chest pain to coughing, irritation and, on prolonged exposure, damage the heart and lungs.
“Black carbon is released during incomplete combustion of fuels (like wood from the forests).
Ozone is produced when poisonous gases like carbon monoxide react with sunlight,” Prof Manish Naja, head of the atmospheric science division at the Aryabhatta Research Institute of Observational Sciences (ARIES) at Nainital, which observed the dangerous spike.