Across India’s five metros (excluding Kolkata which is yet to set up air monitoring stations), India recorded 55 days that were Satisfactory and 48 that were Moderate. Only Bangalore saw days that had Good air quality.
Chennai recorded more days that had Poor air quality than any other city. Delhi recorded one Severe day on 4th May. Here’s the air quality broke down for each city by number of days.
Missing Data Days
Both Delhi and Mumbai were able to record the air quality every day during May. Hyderabad failed to report air quality levels on two days, Bangalore missed 11 days and Chennai wasn’t able to report readings 14 days out of 31.
The Environment ministry needs to do a lot more to ensure that it gets real time, accurate data to the population every day without fail.
Air Quality Over Time
Delhi saw a large spike in levels of pollution early on in the month before trailing off, likely due to favourable weather conditions such as rain and wind.
Note that the gaps in the lines is where data is missing for that particular day.
US Consulate Air Quality Readings of Indian Cities
Often the most reliable and up to date information about the air quality of the five metro cities comes from the US Consulates in Delhi, Mumbai, Kolkata, Hyderabad and Chennai.
The caveat of course is that air quality readings are only valid for the local area and since the US Consulates are often located in the centre of the cities, the readings tend to be higher than the official figures.
The other caveat which makes comparing official data to US Consulate data difficult is that the US Consulates provide hour by hour meter readings rather than a daily average. The readings below were all taken in the morning between 9 and 12 noon but the air quality could vary throughout the day.
In this chart we consistently see Delhi as recording higher levels of pollution than other cities.
When we break down the chart above to see the number of days the air quality was at different levels, you can see how Delhi had significantly more days when the air quality was Unhealthy. Delhi recorded 20 days where the air quality was Unhealthy, followed by Hyderabad which recorded four Unhealthy days.
On most days, air quality was either Moderate or Unhealthy For Sensitive Types for cities across India. Remarkably, Mumbai recorded more Good days than any other Indian city and had overall better air quality, although this could just be down to the location of the consulate.