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Air quality remains in emergency levels due to low-speed winds
New Delhi Air quality in Delhi continued to remain in the emergency levels on Friday, as wind speed started picking up only after noon, experts said.
New Delhi Air quality in Delhi continued to remain in the emergency levels on Friday, as wind speed started picking up only after noon, experts said.
The Central Pollution Control Board (CPCB)-led task force will review the pollution on Saturday to take a call on extending the curbs. According to scientists, air quality is expected to improve on Saturday.
“We will review the situation Saturday, as air quality is expected to improve significantly on account of wind speed picking up. We will see if extending the ban on polluting industries and other such activities is required,” a senior CPCB official said.
According to the CPCB data, Delhi recorded a reading of 458 on the CPCB’s air quality index (AQI), a marginal improvement from Thursday’s reading of 463. Weather officials have predicted further improvement in the air quality but calm winds through Thursday night and early Friday morning pushed the pollution levels further into the emergency zone. It wasn’t until the sun cleared by in the city by noon that the wind speed picked up.
The level of ultra-fine particulate matter with diameter less than 2.5 microns, PM2.5, remained above 300µg/m³ for nearly 80 hours, against the safe limit of 60µg/m³. The PM 2.5 level at 9pm on Friday was 363µg/m³, as per CPCB.
The PM2.5 level started spiking on Tuesday around noon and continued to rise on Wednesday, reaching a high of 506µg/m³ at 3am. There was a marginal dip during the day but the level started spiking again, touching 505µg/m³ on Thursday at 12am. At 5pm on Thursday, the level was at 335µg/m³ and it spiked to 385µg/m³ at 8am on Friday, receding only after noon.
The particulate matter level had shot up on Thursday night because of moisture coming from the northwestern region, as Punjab and Haryana had received light rainfall. “The rainfall in these areas resulted in an increase in moisture, which further trapped pollutants and delayed the dispersal. The relative humidity in the early hours of Friday was 91%, which further trapped pollutants,” the official said.
Prolonged exposure to particulate matter is known to cause respiratory distress and symptoms of asthma. Ultra-fine PM2.5, in particular, can penetrate internal organs, cross the blood-brain barrier and cause damage.
According to scientists with the India Meteorological Department (IMD), with the passing of the western disturbance, the cloud cover reduced, allowing sunlight to reach the surface. Delhi received more sunlight on Friday, in comparison to the past three days.
“The winds were mostly calm on Thursday and afternoon today (Friday), with an average wind speed of 10kmph. By then, the cloud cover had reduced and sunlight had also improved, which helped push some pollutants away,” said Kuldeep Srivastava, head of regional weather forecasting centre of the IMD.
Srivastava said that significant improvement is likely from Saturday and will continue to remain better till Monday. However, another spike in pollution is expected on November 19 and November 20, owing to low wind speed.
The System of Air Quality and Weather Forecasting and Research (Safar), the pollution forecasting wing of the Union ministry of earth sciences (MoES), also forecasted that rain in parts of Punjab and Haryana will impact stubble burning in these regions, thereby, giving some relief to Delhiites. However, the share of crop stubble burning in Delhi’s PM 2.5 levels could not be ascertained because of the thick cloud cover over the region.
“The effective fire counts are only estimation because fires could not be spotted because of the thick cloud cover. Nearly 10% of PM 2.5 level in Delhi came from these crop fires today (Friday)…Because of rain in this region, significant improvement in air quality in Delhi could be seen on Sunday,” the Safar forecast read.
NASA scientists also expressed their concern over the lack of reliable satellite data on Friday because of thick cloud cover.
“Fine particulate matter is on the rise lately in New Delhi leading to an emergency-like situation. Cloud cover is blocking view of fires on ground, so satellites don’t see fire activity,” said Hiren Jethva, research scientist, Universities Space Research Association (USRA) at NASA Goddard Space Flight Center.
