Why Do Air Conditioners Smell Bad?

If you’re noticing a funky smell in your home or office, it may be coming from your air conditioner. Here’s what could be causing the odor and how to resolve it.

Keeping your air conditioner clean is one of the best ways to make sure it isn’t adding allergens and moistures back into the house. However, if you don’t keep them clean at all times, they can end up making your home smell unpleasant, according to a new study from  HKBU.

Lai Ka-man, Ph.D., and her team of scientists from the Department of Biology discovered that skin squames get sucked into air conditioning units, becoming a “lunch” for bacteria living there. Once these bacteria digest, they produce smells such as ammonia (a strong urine odor) and a BO smell (volatile fatty acids).

One of the most significant indoor air-quality problems is odor emission, according to a study. The first-ever study on smelly AC units found that the bacterial process was higher when those units leaked sweat or oiled with dust. Still, now we know it’s not always just about what’s inside: foul odors happen even in seemingly clean systems too! What this means for you and me is that it’s not just AC units emitting foul odors; skin squames from uncleaned furniture can also contribute to foul smells in our homes.

The size of skin squames is generally larger than 10 micrometers, or 0.001 centimeters, and a filter that can effectively capture particles less than this size should help improve the odor problem. It may also be helpful to get an air purifier with HEPA filters which you then use frequently.