Instruct: Classify Amazon reviews into positive or negative sentiment
Query: If it actually worked...

Ok, I don't know if it's the bulb or the purifier system, but I've gone through 3 bulbs in the past six months and it is a joke! The one that came with the purifier was broken when I opened it. The second one worked for 4 months then burned out. These things are expensive ($25) and I would expect it to last a lot longer. The third one I purchased on amazon and it worked for about 30 seconds and then burnt out. Unfortunatley I didn't try it out until 30 days had passed and now I can't return it to the third party seller on amazon. This uv bulb was one of the things I thought was especially nice about this purifying unit and had I known that the bulb was so expensive to replace and only lasts 3-4 months, I might not have purchased the unit. This bulb is a joke.