Hi,
I've bought a figaro sensor TGS2600, that measure the air quality and PM10.
I have readed the datasheet that explanes how it works correctly.
It says that the calibration period, before using, it's 7 days of warming up.
Isn't it??
Thanks! 
up
Not sure what the question is?
In the data sheet it says:-
Conditioning period
before test
That is 7 days.
That means that to get the specification in the data sheet it has to have be on at least 7 days. I imagine this is to burn off all the stuff used in manufacture. After that I don't suppose it has to be on for 7 days before you can read it.