Air quality in Ghaziabad and Noida misrepresented due to missing station readings

Due to the unavailability of readings from two air-quality monitoring stations—Sector 62 in Noida and Loni in Ghaziabad—the twin cities of Ghaziabad and Noida, which were suffering from "very poor" air quality on Nov 4, were placed in the "poor" category of the air quality index (AQI) on Nov 5.

These cities, which have high pollution levels after Diwali, reported 24-hour average AQI readings from all four stations in the two cities on Nov 4, with AQI levels of 314 and 319, respectively, falling into the "very poor" category.

According to the Central Pollution Control Board's (CPCB) daily AQI bulletin, Greater Noida had an AQI level of 291 in the "poor" category, while Ghaziabad and Noida had AQI values of 268 and 265, respectively.

Only three stations were used to calculate the AQI readings for Ghaziabad and Noida.

Four monitoring stations are located in the Ghaziabad district: Indirapuram, Loni, Sanjay Nagar, and Vasundhara.

According to the CPCB, Loni had been experiencing high pollution levels and was mostly responsible for the city's AQI values on Nov 2, 3, and 4, which were 377, 383, and 350 (past 24-hour average at 4 p.m.), respectively.

According to officials, Loni's numbers did not match the AQI values that were made public on Nov 5.

“We do not know about the Loni station, but it could have been due to some malfunction or technical snag that its readings were not available. Otherwise, the activities under the Graded Response Action Plan are underway to help improve polluted conditions,” said Vikas Mishra, regional officer at the Uttar Pradesh Pollution Control Board (UPPCB).

The CPCB classifies AQI as follows: 0–50 as “good,” 51–100 as “satisfactory,” 101–200 as “moderate,” 201–300 as “poor,” 301–400 as “very poor,” and over 400 as “severe.”

On Nov 2, 3, and 4, the Sector 62 station in Noida recorded high average AQI levels of 349, 323, and 349, respectively.

“The Sector 62 station had been recording high pollution levels, and its readings were not available on Tuesday due to some issue. This monitoring station is managed by the India Meteorological Department,” said Utsav Sharma, regional officer at UPPCB, Noida.

“There must have been some snag or technical issue in getting the readings. Therefore, the readings from only three stations were averaged. However, it was also observed that Noida’s AQI started to lower down since Tuesday afternoon,” he added.

According to environmentalists, additional monitoring stations in various locations are necessary for the cities in the National Capital Region (NCR) to get a complete picture of pollution levels.

“The overall AQI of the city is provided only on the basis of readings from four stations, and this is not comprehensive. If there were more stations, the overall scenario might change due to the availability of more readings from different areas,” said Sushil Raghav, a Ghaziabad-based environmentalist.

On Nov 5, the AQI for the neighboring cities of Delhi and Gurugram was 373 and 298, respectively.

However, in a forecast released on Nov 5, Delhi's air quality early warning system indicated that a lower ventilation index, with an average wind speed of less than 10 km/h, was unfavorable for the dispersion of pollutants.

The system predicted that meteorological conditions would likely remain extremely unfavorable for the dispersion of pollutants.

Additionally, it forecast winds of 4–8 km/h across Delhi on Nov 6 and 7. According to the forecasts, stubble burning increased its share of Delhi's PM2.5 concentration from 19.72% on Nov 3 to 23.36% on Nov 4.