Truly works! My upstairs neighbor’s smoking was becoming unbearable so I was praying this would work- and it didn’t let me down. I’ve tested out it’s “sensing abilities” which seems ridiculous but I wanted to see if it was truly reading the air. It has picked up on smoke from cooking, perfume, nail polish, and cigarettes thus far. Very happy with this purchase. Well worth the money if you have airborne nuisances or allergies.