The air over Pakistan is always polluted, but for several months in winter the quality of air becomes almost unbearable and has been getting steadily worse over the years. It is due mainly to the practice of residue crop burning. Residue crop burning takes place at any time of year, and in many places, but it takes longer to disperse in winter due to various meteorological factors. Residue crop burning occurs when one crop is harvested and the fields prepared for the planting of the next major crop. If the authorities come down heavily on crop burning and the burning of trash, it would impact very positively indeed on the air quality and the health of the nation.

Source: Pakistan Today January 21, 2019 12:22 UTC