The filter itself smelled just fine, it looked clean and was easy to install. However, after leaving the room and coming back, suddenly for the first time ever my entire room smelled very gross. It wasn't exactly a chemical smell, just a bad one. I tried my little mini air purifier and the green light indicator turned red when I put it in the Conway filtered air. So I ran the conway near the door for a while to let the filter get a chance to breathe it out... It still smelled so I wrote to Amazon and they offered a replacement. While I was waiting for the replacement the smell improved and my little air purifier was happy and green again. Still, I think there is something wrong with the filter so I installed the replacement and it does not seem to be creating the same strange smell. I am returning the old filter. If any smell comes this time I will just run it near the outside door a bit to let it get the smell out of its system. I am not sure what it was but it seemed to be a passing thing.