It was unable to record pollution levels in nearly half of the 28 locations it is supposed to monitor due to “insufficient” air pollution data. In certain other locations, it indicated “moderate” air quality though real-time monitoring by the Central Pollution Control Board (CPCB) and the Delhi Pollution Control Committee (DPCC) showed high toxicity.
The index is meant to categorise air quality as good, satisfactory, moderate, poor, very poor and severe based on a 24-hour average of three highest pollutants in the region. A look at the data generated in the last eight days, however, shows that of the 11 locations in Delhi, the AQI was unable to monitor air quality in five.
As a result, data for the highly-polluted ITO and Shahdara areas and the industrial zone around the Delhi College of Engineering in north Delhi’s Bawana was not available.
The index’s methodology of calculating the average of three pollutants too seemed to be giving the wrong picture. In certain areas, the index showed air quality as moderate though the presence of particulate matter (PM) — a cause for major breathing ailments — was high.
This was because the low presence of pollutants like sulphur dioxide and nitrogen oxide pulled the average down to the moderate category. This was particularly true for Delhi’s Anand Vihar where the minutest particle level (PM 2.5) on Tuesday jumped to 438 micrograms in one cubic metre of air -- eight times the national safety standard. The index, however, showed the air quality as moderate as sulphur dioxide and nitrogen oxide levels were not very high. Similar was the situation in west Delhi’s Punjabi Bagh.
An official of the CPCB, which runs the index, said these were “teething problems”. “AQI is more reliable as the person does not fall ill by being exposed to high-level of air pollution for a short duration,” the official said. The index, touted to be at par with the global standards, however, is more lax than the one used in the United States and Europe. Air quality which India’s AQI considers moderate would be considered unhealthy in the West.
The index failed to generate data in Agra, Faridabad, Ahemdabad and Hyderabad. Partial data was generated in Lucknow, Chennai and Bengaluru. Air quality in Modi’s constituency of Varanasi’s has consistently been ranked as “poor”.