 "Delhi's air quality deteriorates amid cold wave; likely to remain 'poor'")
Delhi's air quality continued to be in the "poor" category on Thursday (12 December), with the Air Quality Index (AQI) recorded at 263 at 9 am. This was a decline from 207 at 8 am on Wednesday and 224 on Tuesday, based on data from the Central Pollution Control Board (CPCB). However, some parts of the city reported "moderate" air quality.
In fact, the air quality began to worsen again on Wednesday evening, registering a ‘poor’ AQI of 203 at 7 pm and 210 at 10 pm, according to real-time data. Despite wind speeds of 8-10 kmph, the AQI fell due to cold wave conditions, with Delhi's minimum temperature dropping to 4.9 degrees Celsius – five degrees below the seasonal norm.
Air quality likely to remain 'poor'
The Air Quality Early Warning System (AQEWS) predicts that Delhi's air quality will remain in the "poor" category until at least Saturday. A bulletin released on Wednesday evening stated: "The air quality is likely to stay 'poor' from Thursday to Saturday, with the outlook for the next six days also indicating 'poor' air quality."
Notably, Delhi has not experienced a "good" or "satisfactory" air day in December since 2015. The lowest AQI for the month was recorded at 140 on 26 December 2015. The CPCB categorises AQI levels as follows:
- 0–50: Good
- 51–100: Satisfactory
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- 101–200: Moderate
- 201–300: Poor
- 301–400: Very Poor
- Over 400: Severe
Relaxation of Grap-IV restrictions
Recently, the Supreme Court permitted the Commission for Air Quality Management (CAQM) to reduce restrictions from Stage IV to Stage II of the Graded Response Action Plan (GRAP) due to an improvement in air quality last week.
However, the court stressed that Stage III restrictions should be reinstated if the AQI exceeds 350, and Stage IV measures reimposed if it surpasses 400.
Understanding AQI and health impacts
The AQI measures air pollution and its effects on health:
- 0–50 (Good): Clean air with minimal health risks.
- 51–100 (Satisfactory): Generally acceptable but may affect a small number of sensitive individuals.
- 101–200 (Moderate): Mild health discomfort for sensitive groups.
- 201–300 (Poor): Increased health risks for vulnerable groups like children and the elderly.
- 301–400 (Very Poor): Significant health risks, especially for those with pre-existing conditions.
- 401 and above (Severe): Harmful to the entire population, with a high likelihood of respiratory issues.