Delhi's air quality improves, settles at 'very poor' level

The air quality in the national capital improved and settled at 'very poor' category on Wednesday, even as Delhi continued its battle with pollution.

While the Central Pollution Control Board (CPCB) data showed the overall air quality index (AQI) at 'very poor' level of 399, the Centre-run System of Air Quality and Weather Forecasting (SAFAR) showed an AQI of 385 which falls in the very poor category.

While the PM10 level -- fine particulate matter in the air with a diameter of less than 10 micrometres -- settled at 394, the PM 2.5 level was at 230, both of which fall in the 'very poor' category.

In view of the prevalence of severe pollution in the national capital, industrial activities in pollution hotspots of Wazirpur, Mundka, Narela, Bawana, Sahibabad and Faridabad, and construction work across Delhi-NCR will remain shut till Wednesday. They will remain closed until Wednesday, EPCA Chairperson Bhure Lal had said.

In a letter to Delhi Chief Secretary Vijay Kumar Dev, Lal had also directed him to ban all construction activities in the national capital, Faridabad, Gurugram, Ghaziabad and Noida till Wednesday.

The EPCA directed the traffic police to deploy special teams and ensure congestion-free traffic flow, particularly in identified high-traffic corridors.

The agencies concerned have also been asked to ensure strict action against illegal industries, intensify ground action and make all efforts to control polluting activities, particularly waste burning.

In a health advisory, SAFAR asked Delhiites not to rely on common dust masks for protection.

The agency has advised people to avoid all outdoor activities, such as 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 an incense," it said.

The advisory also recommended frequent wet mopping and using masks known as N-95 or P-100 respirators only for outdoor activities.

"Do not rely on dust masks for protection," it read. 

Earlier on Tuesday, the CPCB data had shown the overall the AQI at 'severe' level of 408, the SAFAR had shown an AQI of 385 which falls in the very poor category.

Twenty-three areas had recorded severe pollution level, while 12 areas witnessed very poor air quality, the CPCB data had shown.

In NCR, Ghaziabad recorded severe air quality while Faridabad, Gurgaon and Noida recorded very poor air quality. The overall PM2.5 level was recorded at 263 and the PM10 level at 400, the CPCB had said.

Delhi's air quality turned 'severe' on Saturday. The national capital recorded its second-highest pollution level of the year on Sunday with an AQI of 450.

According to SAFAR, Delhi's overall air quality is expected to improve due to increased wind speed. "The forecasting model predicts a faster improvement due to faster dispersion. The AQI will go back to the very poor category by tonight for the next three days," it had said.

According to the Indian Institute of Tropical Meteorology (IITM), the air quality is likely to improve but will remain in the upper end of the 'very poor to severe' category.

"The wind speed and ventilation index are highly unfavourable for dispersion of pollutants," it had said.

Ventilation index is the speed at which pollutants can get dispersed. A ventilation index lower than 6000 sqm/second, with average wind speed less than 10 kmph, is unfavourable for dispersion of pollutants. The index was 5000 sqm/second on Tuesday, the IITM had said.