NEW DELHI: Pollution in the city eased considerably today, a day after a spike was recorded across several areas, with the level of fine respirable pollutants showing a steady reduction.
Although the eight-hour average of ground-level ozone, a gaseous pollutant, continued to rise and settled close to 60 parts per billion (ppb) in the 'moderate' category.
Ground-level ozone, as opposed to stratospheric ozone which shields the earth from ultra-violet rays, is a product of chemical reaction between oxides of nitrogen (NOX) and carbon monoxide (CO) among others in the presence of strong sunlight.
The marked reduction in PM 2.5 and PM 10, that are harmful on prolonged exposure, can be attributed to a rise in local wind speed across the city which helped in sweeping away the pollutants.
At Anand Vihar, a pollution hotspot, horizontal wind speed around 8 PM was 2.8 metres per second. PM 2.5 and PM 10 concentrations were at 77 and 343 micrograms per cubic metre respectively.
The average levels of PM 2.5 and PM 10 was recorded in the moderate category at 90.2 and 210 micro grams per cubic metre by SAFAR. Their corresponding safe limits are 60 and 100 respectively.
Green body TERI said the fluctuations observed in pollutant concentrations are caused due to meteorological variations, changing emissions during the weekdays, and background influences.