The severity of pollution in Delhi and NCR is poor to very poor, falling in the category of unhealthy to hazardous at present. The AQI for most of the places is between 200 and 300. Generally, also, the air quality starts deteriorating during the month of October.
The main factors for increased pollution level are many, mainly fall in minimum temperatures, light and variable winds. Due to low temperature, haze or mist tends to form during morning hours and since the winds are light in nature, the haze persists for longer duration. The particulate matter gets deposited on the water vapors available in mist and haze. Subsequently, leading to increased pollution levels.
However, this time the air quality has not deteriorated to severe as the smoke from stubble burning in Punjab and Haryana is not reaching Delhi and NCR with a severe intensity. This is because the northwesterly winds are not setting for a longer duration which would have carried smoke particles over Delhi and NCR.
There has been a continuous passage of Western Disturbances which induces Cyclonic Circulations over North Rajasthan and sometimes Haryana. These phenomena are responsible for change in wind direction, like at times, winds start going from southwest and gradually it changes to southeast. They then restrict the pollutants from Punjab and Haryana to reach Delhi and NCR.
However, this will not be the case as soon as we slip into the month of November. The moment minimums will further fall, it will lead to formation of mist and shallow fog and Delhi will then witness a significant rise in pollution levels.
Diwali is also around the corner, there will be burning of firecrackers which will contribute to the increased pollution levels. Just in case, the nature of winds is light during that time, then we can expect a spike in pollution levels. The concentrations of ambient air pollutants exceed levels associated with increased risk of acute and chronic health problems.
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