The air-quality of the national capital is set to deteriorate further and become "very poor", with the count of pollutants, especially the PM2.5, set to increase drastically.

According to the System of Air Quality and Weather Forecasting and Research (SAFAR), on Monday the PM2.5 concentration was recorded at 117 units, considered "poor" in per the Indian emissions standards. This is, however, projected to increase to 128 units on Tuesday and 122 units on Wednesday, entering the category of "very poor".

The SAFAR officials, however, claimed that the stubble burning in the neighbouring Punjab was not a major contributor to air pollution here.

"These reflections are due to fall in normal temperature and increase in humidity," an official from SAFAR secretariat told .

PM2.5, or the particles in air with diameter less than 2.5mm, is one of the major and common pollutant with direct consequences on life expectancy.

The international permissible limit for PM2.5 is 25 units (micro gram per cubic metre) while for India it is 60 units.

Further, the official said so far the winds were not coming from the states where stubble burning was being reported.

"Major cause of the drop in the air-quality is because of increase in humidity and temperature fall. Stubble burning is a contributor but not a significant pollutant," the official added.

On Monday, the Air Quality Index (AQI) in Delhi was recorded at 277 index value, considered "poor", while in the neighbouring Ghaziabad it was already "very poor" at 302 index value. In Noida, however, the air-quality was found satisfactory, with AQI recorded at 62 index value.

PM2.5 and PM10 were the major pollution contributors in Delhi, as found by 16 monitoring stations, while PM2.5 were the sole reason for bad air quality in Ghaziabad.

The "poor" AQI leads to breathing discomfort to most people on prolonged exposure, while the "very poor" category leads to respiratory illness on prolonged exposure.