Delhi air visibly cleaner but data ‘missing’ again

The Central Pollution Control Board (CPCB) released its daily air quality index (AQI) bulletin around 9pm—instead of around 5pm—while only partial data, that too for only three cities, was available on the Sameer phone application as of 8pm

Delhi’s air quality improved on Thursday — partly due to favourable meteorological conditions, but also courtesy a malfunctioning air quality monitoring system as real-time data from 34 of 39 air quality monitoring systems in the Capital went “missing”.

Clear skies over Delhi on Thursday. (RAJ K RAJ /HT PHOTO)

This was the third time in the past 30 days that AQI data was not available for hours and was only made available at night.

The Central Pollution Control Board (CPCB) released its daily air quality index (AQI) bulletin — the national bulletin was still not available, but a Delhi-NCR AQI bulletin was made available — around 9pm, instead of around 4pm -- while only partial data, that too for only three cities, was available on the Sameer phone app till 8pm.

The CPCB daily bulletin stated Delhi’s 24-hour average AQI as of 4pm was 177 (“moderate”). Constant checks by HT throughout the day found data from only five of 39 air quality stations being updated on the Sameer app. At 9pm, data from 36 stations was available on the app, with Delhi clocking a real-time AQI of 208 (“poor”).

CPCB officials declined comment on the repeated unavailability of the data.

An official from the Commission for Air Quality Management (CAQM) said on condition of anonymity that there was a glitch in the National Informatics Centre (NIC) since late Wednesday. The official said that pollution data was available, but could not be updated.

“We have checked with CPCB and all monitoring stations in Delhi are operational. However, the data cannot be uploaded online due to technical glitches. We are hoping that the issue will be resolved by late night,” the official said on Thursday afternoon.

Experts, however, said regular and systematic updates in pollution data were essential, especially in Delhi which consistently reports poor air quality through the year, for implementing the Graded Response Action Plan (Grap) curbs on short notice.

“Regular updates on the NAQI platform, Sameer app, and daily bulletin are essential for citizens, public bodies and corporations to take proactive action. NAQI data gaps hinder public actions for reducing their exposure to hazardous air pollution. While CPCB’s central control room for air quality management indicates that stations are collecting and reporting data, a technical glitch seems to be disrupting AQI calculations. This is the third such lapse this year, highlighting the urgent need for a system upgrade to prevent future disruptions,” said Sunil Dahiya, founder and lead analyst, Envirocatalysts.

There has not been a single day this when the daily AQI bulletin has reflected the average data from all 39 monitoring stations in the city. On January 26, the average pollution level was calculated based on 27 stations; on January 8 and 9, data from 28 stations was counted; and on January 10, 22 and 27, data from 29 stations was considered.

Forecasts by the Centre’s Early Warning System for Delhi (EWS) showed that air quality is likely to be in the “poor” category from Friday to Sunday and may deteriorate further.

Meanwhile, the minimum temperature on Thursday was 8.2 degrees Celsius, around 1.2°C below normal, while the maximum temperature was 23.6°C, three degrees above normal. Mist was reported at Safdarjung airport, which also recorded its lowest visibility at 1,500 metres, at 7am.

“There has been a fall in minimum temperatures up to 23°C over Delhi-NCR during the past 24 hours. Shallow fog or mist likely in the morning on Friday with mainly clear sky. Strong surface winds of speed 20-30 kmph are likely during the day,” the India Meteorological Department said in its prediction.