New book traces how farm ammonia worsens north India's air pollution

In The Nitrogen Bomb, journalist Jacob Koshy examines how ammonia, largely from agriculture, worsens air quality across the Indo-Gangetic Plain, a 2,500-km intensively farmed belt home to nearly half a billion people. He cites a CREA study finding secondary pollutants such as ammonium sulphate, formed when coal-plant sulphur dioxide meets farm ammonia, cause nearly a third of India's PM2.5.