so yeah, you might not feel much difference if the purifier is able to clean the air within a few minutes. worst days, you would notice the difference as soon as you get out of the house and smell that outside air after staying indoors. i can already do so in evenings here in gurgaon. assuming you are not living in some secluded posh area of delhi with little pollution (hehe), you would probably get to see the machine struggle in a few weeks time.