Forest fires and emission of air pollutants, which include fumes from vehicles running on diesel and slow burning of coal and charcoal, release isocyanic acid in the troposphere. In 2011, scientists first detected isocyanic acid in the ambient atmosphere at levels that are toxic to human populations; at concentrations exceeding 1 parts-per-billion by volume (ppbv), human beings could experience tissue decay when exposed to the toxin.

via Gas from pollutants, forest fires at potentially toxic levels.

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