The ongoing lockdown has created a unique opportunity to study various elements contributing to air pollution in a controlled environment.

There is a considerable fall in AQI levels across the country.

We compared AQI Levels in 8 cities for 16 days (Mar 18 to Apr 2) across 4 years (2017 to 2020).

March is a good month to study air pollution as there are no seasonal spikes due to dust storms or paddy burning; & pan-India there is hardly any rain. However, for the same days, in 2017-19, AQI levels in North Indian cities North Indian are in the range of 170-250.

Key changes that have happened pan India during the lockdown are:

• Very minimal vehicular movement
• No industrial activity & reduced usage of diesel gensets
• No construction activity
• No flights & air traffic (Impact shall be only in Delhi, Bangalore & Mumbai)

Key factors that has not changed during these lockdown days is:

• High percentage of fossil fuel based energy generation in India. (It is possible that PLF has been reduced but we do not have exact data yet)

Initial Observations

• The AQI dropped in a matter of 2 days, establishing the fact that change in parameters rapidly change AQI, it was not as if PM2.5 remained suspended in the air.
• %age fall far greater in highly polluted cities in North India compared with Mumbai, Bengaluru and Chennai.
• In fact Delhi's AQI is now similar to Bengaluru's AQI. This means that latitude, climatic condition, soil and other geographical differences impact on pollution is minimal.
• Both Delhi-NCR & Bengaluru have typically high vehicular movement, high backup power gensets using diesel & high construction activity.
• The differences in average AQI in Bengaluru & Delhi for the same period (across 2017-19) could be attributed to higher number & density of on-road vehicles in Delhi.
• The average difference in AQI (for same period between Delhi & Bengaluru) is 150 in 2017, 100 in 2018 & 60 in 2019; Delhi being more polluted.
• This fall in gap in AQI levels could be indicating the increasing number of vehicles in Bengaluru or the impact of peripheral highways in Delhi.

Way Forward

We need both regulatory action, to work along with public & private investments to ensure that air pollution reduces once complete economic activity resumes. Our indicative steps for all Indian metros are as follows:

• Take regulatory action to tackle construction dust; & make the Central Vista project as a case study in dust containment.
• Mandate strictest laws for any kind of construction.*
• Mandating usage of fly ash bricks in construction.*
• Compulsory tarmacked road near construction sites for transportation vehicles.*
• Eliminate use of gensets for backup electricity generation by upgrading grid to ensure regular supply of electricity to end consumers.
• Promote & invest in electrification of vehicles.
• Reduce congestion on roads by increasing traffic speeds, at all main roads of a city speed of traffic should not be below 50kms per hour.

* Courtesy Chetan Vashistth – https://bit.ly/2UW6lQK

AQI Comparison data – COVID Lockdown