The air quality of the national capital turned severe on Wednesday due to adverse meteorological conditions that remained unfavourable for dispersion of pollutants. According to the Central Pollution Control Board (CPCB) data, the overall air quality index (AQI) in the city reached 437, which is in the 'severe' category. Twenty-six areas in Delhi recorded 'severe' air quality, while three areas gauged 'very poor' air quality, it said. According to the data, Ghaziabad, Faridabad, Gurgaon and Noida recorded 'severe' air quality.
The overall PM2.5 level (fine particulate matter in the air with a diameter of less than 2.5 micrometres) in Delhi was recorded at 315 while the PM10 level was at 499, the CPCB said.
An AQI between 100 and 200 comes under 'moderate' category, 201 and 300 is considered 'poor', 301 and 400 'very poor', while that between 401 and 500 is 'severe'.
Wind speed is likely to remain "highly unfavourable" for dispersion of pollutants till Wednesday, the Indian Institute of Tropical Meteorology (IITM) said. According to experts, even healthy people find it hard to breathe when air quality level is at 'severe' and doctors advise physical activity to be kept at a minimum.
Delhi's air quality was in the 'very poor' category on Tuesday, before deteriorating to 'severe' on Wednesday as it was on Monday. The Centre-run System of Air Quality and Weather Forecasting (SAFAR) said other than surface wind speed, all the rest meteorological factors are likely to be "unfavourable".
"An active western disturbance is very likely to cause fairly widespread moisture intrusion over northern region, including Delhi. Moderate fog will prevail and helping both gaseous and particulate pollutants to be stagnant near the surface," the SAFAR said.
In a health advisory, it asked Delhiites not to rely on common dust masks for protection. The agency has advised people to avoid all outdoor activities, including taking walks.
"If the room has windows, close them, if the air conditioner provides a fresh air intake option then choose it, avoid burning anything such as wood, candle or even incense," it said.
SAFAR has also recommended frequent wet mopping and using masks known as N-95 or P-100 respirators for outdoor activities. "Do not rely on dust masks for protection," the advisory stated.