New Delhi: The air quality of the national capital and surrounding areas saw slight improvement from near "severe" to very-poor" on Friday as winds continue determining Delhi's pollution level.

On a brighter side, the air quality will not drop until November 5, said System of Air Quality and Weather Forecasting And Research (SAFAR), adding surface wind speed has picked up slightly, which is good for dispersion. SAFAR comes under the Ministry of Earth Science.

On Friday 4 pm, Delhi's air quality Index was 370 against 393 some 24 hours back. Faridabad in NCR continied to be in 'severe' category with AQI of 406 on Friday against 407 on Thursday. Gurugram, Greater Noida and Ghaziabad also saw improvement with AQI 389, 376, 370 -- all at upper reach of "very-poor". The AQI becomes severe after AQI is beyond 400.

Winds from eastern directions helped with dispersion of the particle pollutants in Delhi on Thursday night and Friday morning, slightly improving the air quality.

The Air Quality is supposed to stay the same, or may slightly improve for the next two days. However by November 5 pollution will shoot up, says SAFAR.

On Thursday, particle pollutants dipped, from 'severe' to 'very-poor' and 'poor' category.

The PM2.5 and PM10, or particles with diameter less than 2.5 and 10mm, in Delhi was 216 adn 393 microgrammes per cubic meters, against 241 and 437 units on Thursday respectively.

The permissible limit for PM2.5 and PM10 is 60 and 80 units by national standards and 25 and 50 units by international standards.

"Westerly Disturbances at this stage appears to be working towards improving the air quality by making atmosphere unstable over Delhi and favour mixing of the pollutants at least for the next two days to offset the other adverse weather impacts," said SAFAR.

It, however, added that the air quality is likely to be impacted adversely from Monday onwards.

SAFAR has advised people to avoid all outdoor physical activities. Those with asthma must keep relief medication handy, it added.