What are your thoughts on air purifiers?

Most of us live and work in buildings that have air filters, but many of us with allergies, etc. also have air purifiers. Is this a redundant mechanism?

I did get my job to agree to my getting an air purifier for my office, but I am still a bit miffed by their response. I let them know that I frequently get dry itchy eyes and an irritated nose while at work, and that I would thus like to order a small air purifier for my desk. (Note that the assistant pastor in the office next to mine already has one that the church purchased for him.)

My request was met by the following: “I don’t expect that a unit like that will do much when fighting against the air handler unit for the church, but if you would like to try it, I don’t mind.”

I thanked the respondee and left it at that, but I don’t understand why he doesn’t understand that the air handler unit is obviously not adequately handling the dust in my office. Not to mention, we are in an area of the country that is experiencing really bad air quality right now, due to the smoke coming down from the Canadian wildfires. I am sitting in my office with the door closed, with the doors to the outside some 30 feet or so away from my office door, and I can smell the smoke in the air.