Why does AQI vary so much within a city?

NEW DELHI: If you are baffled by the divergent data on air quality and the countless numbers being released, for those who live in and around Delhi, it may be a good idea to familiarize yourself with the Air Quality Index () and the numbers behind since bad air has become an annual accessory.

Under the US system, only PM 2.5 values ​​are taken to determine the level of contamination and the AQI number. Under the US system, values ​​above 500 are considered beyond the AQI.

The air quality monitors of the Embassy and Consulates of the United States measure fine particles suspended in the air (commonly referred to as PM 2.5 because they have a diameter less than or equal to 2.5 microns) in embassy compounds and Consulates. The caveat is that data from a single monitoring station cannot be applied to an entire city.

Air quality data collected at the U.S. Embassy and Consulates. UU. They may differ from other monitors located in the same city.

According to the Indian calculation, the Central Pollution Control Board (CPCB) and Safar India grant an index value for AQI, which is a numerical scale used to inform the daily air quality with respect to human health and the environment .

The CPCB launched AQI for the effective communication of the state of air quality to people in terms that are easy to understand and that transforms complex air quality data of several pollutants into a single number (index value), nomenclature and color

There are six categories of AQI: good, satisfactory, moderately contaminated, poor, very poor and severe.

Therefore, there is a unique AQI number or index value that CPCB publishes or Safar India, another official data source, publishes.

The AQ subscript and health points are developed for eight pollutants (PM10, PM2.5, NO2, SO2, CO, O3, NH3 and Pb) for which national short-term ambient air quality standards are prescribed (up to 24 hours) .

In addition to AQI, there is a count of the main pollutants, PM 10 and PM 2.5, which are provided separately by these monitoring and forecasting agencies.

In addition, there will be different AQI scores for different locations in a large metropolis such as Delhi. For example, at 5.15 p.m. On Friday, the AQI in Delhi in different places ranged from 450 in Vasant Vihar to a maximum of 643 inches.

The AQI in different locations was mapped in Kalkaji (544), Okhla (553), Tughlakabad (588), Mundka (610), Punjabi Bagh (600) and Anand Vihar (602), all with variable readings.

With the public health emergency declared, experts say the announcement could have come earlier.

Tanushree Ganguly, Program Associate, Energy, Environment and Water Council, said: Delhi has been experiencing severe air quality conditions for the past four days and PM 2.5 levels have now exceeded 300ug/m3. While declaring a public health emergency today is definitely a welcome move, the announcement could have come earlier.

She said authorities should consider reducing the concentration threshold necessary to declare an emergency so that vulnerable sectors of the population are not exposed to such high concentrations of PM2.5. In addition, at such high levels of environmental concentration, indoor air quality also worsens.