Air Quality Index

Air quality Index(AQI) measures the quality of the air we breathe. With more than 1/6th of the world’s population leaving in India and with one of highest population densities it becomes imperative to find the true source of these pollutants. Congregation of data points with a low AQI, helps the government plan their future course of action to curb source of these pollutants.
In this Data Visualization we see the impact of COVID-19 lockdown on the Air Quality Index in India. The Air quality Index is calculated by measuring the following pollutants:

1. Nitrogen Oxides

2. Ozone

3. Benzene, Toluene and Xylene

4. Carbon Monoxide

5. Ammonia

6. Sulphur Dioxide

7. Particulate Matter

These pollutants are measured and a value is given called the Air Quality Index. On the right we have the AQI scale. The data was downloaded from this link: https://www.kaggle.com/rohanrao/air-quality-data-in-india

[1] "Here is the list of AQI levels and AQI buckets"

Source:https://www.health.nsw.gov.au/environment/air/Pages/aqi.aspx

The pattern of polutants from 2018-2020

• Before seeing the impact of COVID-19 Lockdown on the AQI of India.
• We first see the pattern of pollutants across the years from 2018-2020
• We can see that intensity of the pollutants is high during the months of Oct-Dec.
• This pattern is seen because people tend to burn biomass during Oct-Dec(Winter). Source: https://www.kent.co.in/blog/winter-and-air-pollution-why-does-air-quality-deteriorate-as-temperature-drops
• The pollutants such as Particulate Matter and Nitrogen Oxides have a higher intensity than other pollutants during Winter.

Barchart Race of AQI Levels for 9 Cities in India

• This visualization is a bar chart race among nine cities with their AQI Level. The reason to choose nine cities is that it has the most recorded data compared to other cities.
• We can see that Ahmedabad, Delhi, and Patna have the highest AQI level than other cities.
• In India, the lockdown began on 23rd March. If we look at the visualization, on Feb 2020, the average AQI for Ahmedabad was at 547.6(hover on the bar graph to see the value), which drastically reduced after the lockdown, March Average AQI= 268.5 and April Average AQI= 120.7. The same transition can be seen for other cities as well.

Which city is most polluted in India?

• The previous visualization, we saw the AQI for the cities.
• It is also essential to see the intensities of different pollutants in each city.
• Ahmedabad and Delhi are on the top 3 list for every pollutant. Followed by Patna and Lucknow.
• Ahmedabad ranks 1st for every pollutant except the PM. Delhi ranks highest for PM.
• This is the reason Delhi has the most damaging fog during the Winter season.

AQI level of Top 3 cities from 2018-2020

• As we saw from our previous visualization, Ahmedabad, Delhi, and Patna always have ranked in the top 3 places.
• We also saw from our previous visualization the intensity of pollutants was high during the winter season, and it won’t be right to compare the data between Mar2020-Jun2020 to those winter season.
• Therefore, this visualization compared the first six months from 2018-2020 for the top 3 cities.
• It is very clear that the average AQI for each city had reduced sharply.
• If you see for the AQI index is below<150 after March 2020 for all three cities, which is never seen in the past years.

Ahmedabad Pollutants(ug/m3) from 2019-2020 (Before and After Lockdown)

• This visualisation compares the pollutants before and after lockdown in Ahmedabad.
• The dotted vertical lines represents the day the lockdown began.
• The pollutants have substantially decreased after the lockdown.
• PM for Ahmedabad had a hike on 3rd Jun 2020, but the PM level is still low after the lockdown.

Delhi Pollutants(ug/m3) from 2019-2020 (Before and After Lockdown)

• This visualisation compares the pollutants before and after lockdown in Delhi.
• The dotted vertical lines represents the day the lockdown began.
• The pollutants have spectacularly reduced after the lockdown except O3 for Delhi

Patna Pollutants(ug/m3) from 2019-2020 (Before and After Lockdown)

• This visualisation compares the pollutants before and after lockdown in Patna.
• The dotted vertical lines represents the day the lockdown began.
• All the pollutants have radically reduced after the lockdown for Patna.

Air Quality Index of Indian States in 2019

• As we saw in the first story, value of AQI is put under different AQI buckets.
• This visualisation represents the Indian states with their AQI Bucket and AQI Value(hover to see the value) for 2019.
• States such as Gujrat(497.9), Bihar(218.08), and Delhi(221.6) have hazardous air quality.
• These are followed by Haryana(184), Madhya Pradesh(161) and Uttar Pradesh(180). No data was available for the NA cities

Air Quality Index of Indian States in 2020

• This visualisation represents the Indian states with their AQI Bucket and AQI Value(hover to see the value) for 2020.
• Most of the state’s AQI has reduced due to lockdown.
• Only state which is in hazardous bucket is Ahmedabad. Even though the AQI bucket has not changed. The AQI level is dropped from 497.9 to 232.8 AQI.
• States such as Bihar(132),Delhi(172) have reduced from hazardous bucket to poor and very poor AQI buckets respectively. No data was available for the NA cities

Therefore, we conclude that the COVID-19 lockdown has brought a spectacular change to the Air quality in India.

Reference

[1]. Kaggle.com, 2020.Air Quality Data in India (2015 - 2020). [Online] Available at: https://www.kaggle.com/rohanrao/air-quality-data-in-india [Accessed 20 October 2020]. [2].Kent.com, 2019.Winter and Air Pollution. [Online] https://www.health.nsw.gov.au/environment/air/Pages/aqi.aspx Available at: https://www.kent.co.in/blog/winter-and-air-pollution-why-does-air-quality-deteriorate-as-temperature-drops/ [Accessed 25 October 2020]. [3].health.nsw.gov,2020. Air Quality Index (AQI) and activity guide. [Online] Available at: https://www.health.nsw.gov.au/environment/air/Pages/aqi.aspx [Accessed 25 October 2020].