Air purifiers usually operate by recycling the room’s air through a fan and a filter system.  Generally speaking, it’s difficult to purify the air in large and open spaces.  Large living rooms or large family rooms with high ceilings present a problem.  It’s a challenge to effectively filter the air in such large spaces. Therefore it is extremely important to pick out the most appropriate air purifier for the amount of space.  It’s also important to consider the placement of the clean air machine.  For example, for a large family room, you should place the purifier air coming out of the air purifier towards the place where the majority of the rooms occupants.  When placing a unit in your home, you should place the unit anywhere between 5 and 10 feet from where you will spend your time.  If it is too close, you might feel a draft from the purifier exhaust.  If it’s too far away, then you won’t be breathing in the cleanest air.

You should leave your air purifier on all the time.  It’s redundant to say that you can’t purify your air if your air cleaner is not on.  Since air purifier motors are quiet this shouldn’t bother you if you are doing something quiet, like reading a book.  Air cleaners today are also very energy efficient, don’t get hot and do not consume a large amount of electricity so it’s not a drain on your finances to leave the unit on when you leave.  Since they don’t get hot you don’t have to worry about it setting fire to your home.
Air quality experts recommend turning your clean air machine on its highest setting when you are away as this allows the maximum output and air exchanges per hour.  If the highest fan speed setting is too loud to tolerate when you are in the room, it’s a good idea to leave it on the highest setting when you aren’t home so you can breathe the cleanest air when you return.