How long can flu particles live in the air?

Will they weaken as the day goes on? So if someone has sneezed with the flu, a workman at our house said he was busted with the flu!? He sneezed and he was in my room and brothers room fitting satellite tv freeview! So will the flu particles in the affected areas be weaker this evening than this morning? I am taking all precautions! I took a vitamin c drink and will continue that, I cleaned the surfaces and remote controls in my room with dettol disinfectant spray, washed my hands thoroughly and hell I even have been covering my mouth and hood with my hoody which my mum thought was just taking the P Iss and too extreme lol! Is their a spray you can get to spray in the air to kill flu particles? I might take a lemsip tonight just incase to stop any flu in it's tracks! I'm worried about getting flu cause I have congested sinus problems since end of April!????