Well the IAQ(Index of Air Quality) is not given, because the calculation that gives this index cause too much power consummation, and the node won’t be able to sleep properly. You can read more about this here.
What you can do is to put an addition to your decoder that will calculate the IAQ shown on this post and you will be able to see it in the decoded payload.
Thanks to that you noted and we will change the documentation and the info in the store to make this clear to future customers.
Best regards
Nikola