Throat infections ...hmm...

I see lots of people coughing wherever I go to these days...I enter the lift and I stumble upon people who keep on coughing...I go to the central park in Ghansoli...out of 2, atleast 1 random person keeps coughing...I am not exception...this coughing situation has been a recurring problem for my family for past few weeks...All looks ok on a day and very next day we all start coughing... Is it the AQI or is it the water which is causing this situation??