Delhi’s air in emergency zone for third straight day
NEW DELHI: A blanket of haze and smoke enveloped Delhi for the third consecutive day on Thursday as pollution levels remained above the ‘emergency’ zone for more than 48 hours.
It was the third day when Delhi received diffused sunlight while layer of clouds and smoke formed a toxic combination. But even as government pollution monitoring agencies said air quality was likely to improve on Friday, it would not be much of a relief.
According to Central Pollution Control Board’s (CPCB) officials, a significant improvement is expected only over the weekend. The Delhi government had on Wednesday ordered shutting down of schools till November 15, as air quality was likely to deteriorate further.
The air quality index (AQI) in Delhi, according to CPCB’S 4 pm bulletin, was 463 on Thursday, as against 456 the previous day.
The PM 2.5 levels remained above 300µg/m³ for over 48 hours. The PM 2.5 levels had started spiking on Tuesday around 12pm and continued to rise on Wednesday reaching up to a high of 506ug/m3 at 3am. There was a marginal dip during the day but the levels started spiking again, touching 505ug/m3 on Thursday at 12 am. After 5 pm on Thursday, the levels starting falling and were recorded at 335ug/m3.
As per Indian standards, the safe limit of PM 2.5 levels is 60ug/ m3. The PM10 (coarse dust) level has also been inching closer to 500µg/m³, while the safe limit is 100µg/m³.
Prolonged to exposure to either particulate matter is known to cause respiratory distress and symptoms of asthma. Ultra-fine PM2.5 in particular can penetrate internal organs and cross the blood-brain barrier and cause damage.
“All measures under the emergency category are already in place. As per the weather forecast, we are hoping it will improve slightly on Friday,” said Sunita Narain, member, 0-50 201-300 51-100 301-400
Supreme Court-mandated Environment Pollution (Prevention and Control) Authority.
On Thursday, fresh contribution from stubble burning to overall pollution in Delhi was 13%. But the cumulative contribution was nearly 30% because the wind was not strong enough to blow away the pollution particles. Usually, the last day’s pollution gets dispersed, says a statement by System of Air Quality and Weather Forecasting and Research (SAFAR), the pollution forecasting wing of the union Ministry of Earth Sciences (MOES).
SLIGHT RELIEF EXPECTED
According to scientists at the India Meteorological Department (IMD), slight improvement is expected from the night of November 14 while wind speed is expected to pick up to 12-15 kmph. Cloud cover is expected to reduce, allowing more sunlight to reach the surface in comparison to the past few days. The period between November 15 and November 18 is likely to be relatively better in terms of air quality.
The average speed was 5-6 kmph on Thursday, not favourable for dispersion of pollutants. A 101-200 401-500
Prominent pollutant PM2.5
consistent wind speed of about 10-15 kmph is required for dispersion of pollutants.
“The cloud cover is likely to reduce on Friday, as the existing western disturbance will pass. We are expecting significant improvement in wind speed on November 16 when it could increase up to 25 kmph. On November 19, however, it may dip again to 8-10 kmph,” said Kuldeep Srivastava, head, regional weather forecasting centre, IMD.
Another senior IMD scientist said, “Air quality is likely to remain in the lower end of ‘severe’ zone on Friday. Any significant improvement is expected only on November 16.”
However, experts said, this will not be the end of peak pollution period at least for this time of the year. The pollution levels will keep fluctuating till winter sets in. Pollution levels peak in Delhi in two waves — October-november and December– January.
According to D Saha, former head of the CPCB’A ir quality lab, “Pollution levels will keep fluctuating till winter completely sets in. The transition period from monsoon to winter has varying wind pattern, which combined with pollutants already stagnated in the atmosphere, lead to deterioration of air quality.”
PM2.5
PM2.5