Dear Thej,
FYI, the site you are accessing is for Air Quality Index and not Air Quality.
As a researcher, I am interested in Air Quality Data
Main site is this
Use the advance search option and download the data -- cumbersome process; there are limitations on number of days you can request, depending on the time step you choose. Best is 15 mins and you take care of the weeding out; otherwise asking for day average, the program will give you a value averaging everything it has, which includes -999 and some random numbers.
We keep getting blocked by once in a while from fetching and archiving.
Only last 90 days is online and here is a post to access it
Rest is all stored on aws s3 buckets
There are patches of days missing when the server is blocked by cpcb from fetching and there is not backlog correction method in place.
AQI is useful for PR purposes, but beyond that not so much. Since, this is a calculated value based on 24-hr averages for PM2.5 (for example), it missed the raw instantaneous story.
With best wishes,
Sarath