Delhi's air quality is expected to deteriorate further in the next week due to unfavourable weather conditions, pollutions during Diwali and crop-residue burning in the neighbouring states. So far, the projections suggest that the national capital's air quality will be in \u2018very poor\u2019 category till Saturday. However, it will become 'severe' between November 4 and 9, according to a report in The Indian Express. While speaking to IE, a senior official at IMD explained the reasons behind the rise in pollution in the next few days. He said that on Sunday, an increase in moisture in the air is expected because of an active western disturbance over Himachal Pradesh. Also Read: Delhi air pollution LIVE Updates "An increase in humidity increases the amount of pollutants that can accumulate in the air. Added to that are the calm winds close to the surface. All these factors are expected to increase the concentration of pollutants, especially particulate matter,\u201d he said. According to the report which cited scientists at the System of Air Quality and Weather Forecasting and Research, the contribution of stubble burning is slowly decreasing. Air quality in Delhi has worsened in the last couple of days. Taking a stock of the situation, Union minister Harsh Vardhan said Thursday said that steps taken by states to control crop-residue burning were far from satisfactory. The Delhi government has taken a slew of measures including banning industry units and construction activities to contain pollution in the national capital. The Uttar Pradesh government has also asked its western districts to suspend all construction works between November 1 and 10 to tacke pollution. It has ordered to shut down all the industries using coal and biomass fuel for a week to check pollution.