There are lots of reasons to purchase a personal air purifier. A big one is asthma. This disease can render a person breathless due to microparticles in the air. An asthma attack is like the grinch snatching every last oxygen molecule from your soul. What can set off an asthma attack? pollen, smog, mold spores, dog hair. Different people have diffeerent sensitivies.
A good resource for asthma info is Asthma UK. This is a British charity that does work to help those with asthma. Their mission is to put asthma in the limelight. Remember, a personal air purifer can actually destroy the particles in the air which trigger allergy attacks.