Air remains in poor zone for second day on the trot

The city’s air quality remained in the poor zone for the second consecutive day on Monday, recording a reading of 298 on the Central Pollution Control Board’s (CPCB) air quality index (AQI) bulletin

The city’s air quality remained in the poor zone for the second consecutive day on Monday, recording a reading of 298 on the Central Pollution Control Board’s (CPCB) air quality index (AQI) bulletin. This was a deterioration from Sunday’s AQI reading of 209. Experts said that the air quality had deteriorated since pollutants couldn’t be dispersed on account of calmer winds.

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The level of ultrafine particulate matter having a diameter of 2.5 microns or less (PM 2.5), the city’s primary pollutant was 174.07 micrograms per cubic metre (µg/m³) on Monday, as per the CPCB’s air quality monitor at Vikas Sadan in Sector 11. At the official monitor in Sector 51, the PM 2.5 concentration stood at 388.79 µg/m3 on Tuesday. The PM 2.5 concentration at Gwal Pahari and Teri gram monitors stood at 199.4 µg/m3 and 211.08 µg/m3 respectively, all of which were above the safe limit of 60µg/m³.

As per the System of Air Quality and Weather Forecasting And Research, the average wind speed is expected to be lower than 10kmph on Tuesday, which is unfavourable for the dispersion of pollutants.

VK Soni, the head of India Meteorological Department’s (IMD) environment monitoring and research centre, said, “Currently, the winds were calm. When the wind speed is below 10 kmph we say that winds are slow and not favourable for good air quality. The winds are expected to slow down further from tomorrow afternoon on account of which the AQI is likely to deteriorate tomorrow and day after.”

Sachin Panwar, a city-based air quality scientist, said that local pollutants couldn’t get dispersed due to calmer winds. “The winds were stronger three to four days ago, due to which the dispersion of local pollutants was better. Since calm winds are prevailing now, local dispersion couldn’t take place,” said Panwar.

He said that the pollutants were peaking during the early morning and late night hours whereas afternoons were cleaner. “The AQI takes into account the average value and will always be higher than the absolute value. The pollutants peak at night and the reading takes into account the night time pollution as well,” said Panwar.

As per the early air quality warning system for Delhi-NCR, the air quality is likely to deteriorate and enter the upper end of the very poor category on Tuesday and Wednesday. Subsequently, over the next five days, the air quality is likely to remain largely in the very poor category.

While the IMD’s automatic weather station (AWS) for Gurugram did not record the minimum temperature on Tuesday, the IMD’s AWS at the Palam observatory in Delhi, recorded the day’s minimum temperature at 9.5 degrees Celsius. The city’s maximum temperature stood at 23.5 degrees Celsius.

As per IMD’s weekly forecast, the minimum and maximum temperatures are expected to hover around 8 and 24 degrees Celsius, respectively, on Tuesday. A partly cloudy sky is also expected during the day on Tuesday.