Hello everyone and welcome back to the Cognixia podcast. we talk about something that has been in the news a lot this year and actually makes it to the news for all the undesirable reasons every year for quite some years now. Today, we talk about the AQI or the Air Quality Index. This year, Delhi became the World’s most polluted city in the world, with Mumbai and Kolkatta not far behind in the air quality index. Diwali time makes the air in these cities become absolutely unbreathable, with the rampant air pollution from bursting firecrackers, construction work, industrial pollution, burning the stubbles in farms, etc. and it is affecting the lives and health of everyone in and around these cities.

Air pollution levels in most of the urban areas are a cause of serious concern. It is the right of the people to know the quality of the air they are breathing. However, the data generated by the National Ambient Air Monitoring Network are reported in a form that may not be easily understood by common people. This system of air quality information was found inadequate to facilitate people’s participation in the air quality improvement efforts. With this in mind, the Central Pollution Control Board developed the Air Quality Index for Indian cities as a tool to disseminate information on air quality in qualitative terms, as well as its associated and likely impact on health. The Air Quality Index has six key objectives:

1. Resource allocation

2. Ranking of locations

3. Enforcement of standards

4. Trend analysis

5. Public information, and

6. Scientific research

Let us begin by first understanding what is the Air Quality Index. The Air Quality Index or AQI was introduced in 2015 and aimed at quantifying the severity of air pollution at a particular location. It is measured by recording the levels of multiple pollutants in the air. It is a single composite index that monitors eight important individual pollutants. These eight pollutants are PM10, PM2.5, nitrogen dioxide, sulfur dioxide, carbon monoxide, ground-level ozone, ammonia, and lead. These metrics are measured at different monitoring stations and the metric values are calculated using their average concentration values over a 24-hour span for all metrics except the carbon monoxide and the ground-level ozone metrics, which are measured over 8 hours. The health breakpoint concentration is also taken into consideration when calculating the AQI. Based on this, the worst sub-index value would be taken as the Air Quality Index for the location.