No ‘bad air’ day in Delhi since June 15, courtesy rain and high wind speed
Officials say three monitoring stations, Anand Vihar, ITO and Delhi College of Engineering in Bawana, which are located in heavy traffic zone, are the reasons why the overall air quality was not “good” in the city.delhi Updated: Jul 28, 2017 10:59 IST
Delhi, which is infamous for its foul air quality and has been often dubbed as one of the most polluted cities in the world, has not seen a “bad” air day since June 15, a Central Pollution Control Board official said.
According to him, this is because of meteorological conditions like wind speed and rain in the city and the neighbouring states.
“A large part of the pollution in the city is due to the neighbouring states. This constitutes of nearly 30% of the total pollution in the city. The rain and the moisture in the air have negated these external pollutants and the air quality never went to ‘bad’ level and stayed ‘satisfactory’ after June 15,” Dr Dipankar Saha, additional director and head of the Air Laboratory at the CPCB told the Hindustan Times.
On Thursday, according to the apex pollution body, Delhi’s air quality index (AQI) across seven monitoring stations was 95, which is “satisfactory”. According to the CPCB barometer, air quality falls in the good range if it is 50 or less. The satisfactory range falls between 50-100.
Officials say three monitoring stations, Anand Vihar, ITO and Delhi College of Engineering in Bawana, which are located in heavy traffic zone, are the reasons why the overall air quality was not “good” in the city.
Similarly, the monitoring done by the Ministry of Earth Science’s System of Air Quality and Weather Forecasting and Research (SAFAR), Delhi’s overall Air Quality Index on Thursday was 77. When AQI is below 100, the air quality is considered good and air pollution poses little or no risk. On Friday, too, the AQI is expected to be 72 and it is likely to remain in the same range for the next few days.
The 24-hour rolling average of PM10 and PM2.5 was recorded at 77 μg/m3 and 45μg/m3, respectively on Thursday, according to SAFAR. PM2.5 and PM10 are ultra-fine particles that are the dominant pollutants in Delhi. The acceptable levels of PM 2.5 and PM10 are 60 and 100 microgram per cubic metre, respectively. On Friday, they are expected to be 72 μg/m3 and 42μg/m3, while after another three days these are predicted to be 68 μg/m3 and 38μg/m3.
According to a MeT official, even though it might not be raining in Delhi all the time, the rain in neighbouring areas is of help. “Because of this, long range transport of pollutants from outside Delhi is minimal and therefore this good air quality,” he said.