Tagged unhealthy for breathing
National Capital's Air Quality Index (AQI) was put under 'orange' category and tagged as 'unhealthy' for breathing. Pollution monitoring agencies of both the Centre and the city measured the levels of harmful pollutants above the prescribed limits on Thursday.
City's Siri Fort recorded abnormally higher levels of noxious particles with value of 396 micro gram per cubic. Anand Vihar, RK Puram, Pusa Road, Chandni Chowk, Major Dhyanchand Stadium and Karni Stadium are the areas where levels of Benzene, Particulate Matters, Nitrate Oxide, Ozone were recorded higher than the prescribed limits.
While real time ambient air quality index of US Embassy tagged seven places under 'unhealthy' category, SAFAR (System of Air Quality and Weather Forecasting And Research) cited stubble burning incidents in Patiala (Punjab) and Karnal- Kurukshetra region in Haryana, the reasons behind the sudden rise in the pollutant values on the AQI.
Low surface wind speed and westerly winds are also factors for the low dispersion of Suspended Particulate Matters (SPMs). Forcasting air quality status in Delhi, SAFAR said that Southwest monsoon started to retreat now. The wind speed continues to be slow and variable with predominant direction from the West. "Under these conditions, air quality is predicted to deteriorate to the higher end of moderate for tomorrow. Indications of increased fire activity during the last 48 hours are visible from satellite imagery and further deterioration of AQI is expected for the next two days. Air quality is expected to touch the poor category by 13 October,"
Importantly, calm surface winds will lead to stagnant weather conditions (e.g., low wind speeds, descending air, and compressed boundary layer), which favor rapid fine particulate matter formation and accumulation of pollutants.
"The situation becomes bad if it is encountered with any additional internal (like firecrackers) or external (like stubble) emission source. In a landlocked city like Delhi, it may lead to rapid accumulation and may trigger high pollution events. However, if local emissions are controlled it will be a good check to observe and avoid air quality crises," SAFAR said.