New Delhi, Nov. 9 -- A veil of haze hung over most parts of the city throughout Sunday as Delhi continued to receive a heavy load of pollutants from farm fires raging in Punjab and Haryana, turning the city's air into a toxic cocktail of ultra-fine microscopic particles and gaseous emissions.

For the fourth consecutive day on Sunday, Delhi's air quality index (AQI) was in the severe zone with a value of 416, indicating a health hazard to all those who were exposed to such poor air. Crop fires in the northern states contributed to 29% of Delhi's PM 2.5 load according to estimates by System of Air Quality and Weather Forecasting and Research, Indian Institute of Tropical Meteorology.

The PM 2.5 concentrations touched 250 micrograms per cub...