Farm fires contributed to up to 32 per cent of the tiny PM 2.5 lung-damaging pollutants in Delhi's air - the highest in the past two years during the period of mid-October to early November, according to data from the Ministry of Earth Science. PM 2.5 are fine particles that are 2.5 microns or less in diameter and can travel deep into the respiratory tract, reaching the lungs and entering the bloodstream. "I really feel bad for young children who are going to suffer their lives in this gas chamber," said Dr Ashok Seth, Chairman, Fortis Escorts Heart Institute, Head of Cardiology Council of Fortis Group of Hospitals.