A nail polish remover smell in your apartment almost always means acetone or a chemically similar compound is present in the air. The most common sources are a refrigerant leak from your AC or refrigerator, mold growing behind walls or under flooring, or something a neighbor introduced into shared plumbing or ventilation. The smell is worth investigating because some causes are harmless while others pose real health risks.
Refrigerant Leak From Your AC or Fridge
This is one of the most likely culprits, especially if the smell appeared suddenly and seems strongest near your air conditioner, mini-split, or refrigerator. These appliances rely on chemical refrigerants to cool air, and when older or poorly maintained systems develop a leak, the escaping gas can smell strikingly like acetone or nail polish remover.
A refrigerant leak is not something to ignore. Breathing the gas can cause headaches, dizziness, nausea, impaired coordination, and in serious cases, irregular heartbeat or fainting. Prolonged exposure has been linked to respiratory problems and heart issues. If you suspect a leak, open your windows, turn off the appliance, and contact your landlord or a licensed HVAC technician. You can sometimes spot a leak by applying soapy water to refrigerant line connections and watching for bubbles, but a professional with a leak detector is far more reliable.
One telltale sign: if the smell gets stronger when your AC kicks on or you notice your unit isn’t cooling as well as it used to, a refrigerant leak is very likely.
Mold or Fungal Growth
This one surprises most people. Mold doesn’t always smell musty or earthy. Common indoor molds, including Cladosporium, Penicillium, and Aspergillus, release gases as they grow that can smell exactly like chemical solvents. Research from Georgia Tech’s Indoor Environment Research Program found that growing fungi produce volatile organic compounds including acetone, benzene, and methylene chloride. The researchers noted that many of these compounds are “identical to those originating from solvent-based building materials and cleaning supplies,” which is why the smell can be so confusing.
If the smell is persistent, seems to come from a wall or floor rather than an appliance, and gets stronger in humid weather, mold could be the source. Apartments with past water damage, slow plumbing leaks behind walls, or poor ventilation in bathrooms are especially prone. You may not see any visible mold at all if it’s growing inside walls or under flooring. A musty undertone mixed with the chemical smell is another clue, but it’s not always present.
Sewer Gas Coming Through Your Drains
Every drain in your apartment has a U-shaped pipe (called a P-trap) that holds a small amount of water to block sewer gases from rising into your living space. If you have a drain you rarely use, like a guest bathroom sink or a floor drain, that water can evaporate. Once the trap dries out, gases from the sewer line flow freely into your apartment.
Sewer gas is usually described as a rotten-egg smell, but it’s actually a mix of many compounds, and depending on what’s been flushed into the system, it can take on an acetone or chemical character. In apartment buildings, if a neighbor dumps paint thinner, dye, or cleaning solvents down a drain, you may smell it in your own bathroom even though you didn’t use any of those products. This tends to be temporary. If the smell is isolated to one bathroom, try running water in every drain for 30 seconds to refill the traps. If it clears up within an hour, that was likely the problem.
Paint, Adhesives, or New Materials
If your building recently had renovations, fresh paint applied, new flooring installed, or even new caulking around windows, the outgassing from these materials frequently smells like nail polish remover. Many paints, adhesives, and sealants contain acetone or similar solvents that evaporate into the air for days or weeks after application. This is also true if a neighboring unit was recently renovated, since shared ventilation systems can carry fumes between apartments.
This type of smell is strongest in the first few days and gradually fades. Keeping windows open and running fans will speed the process. If you didn’t have any work done and the smell is persistent, ask your building manager whether maintenance or renovation happened in a nearby unit or in shared mechanical spaces.
How to Track Down the Source
Start by narrowing the location. Walk through your apartment slowly and note where the smell is strongest. If it’s near the kitchen, check behind and around your refrigerator. Near your HVAC vents or wall unit, suspect refrigerant. In the bathroom, try running water in all drains. Along a wall or in a closet with no appliances, consider mold.
Pay attention to timing. A smell that comes and goes with your heating or cooling cycle points to your HVAC system. One that worsens in warm, humid conditions suggests mold. A sudden onset that gradually fades over days likely means a one-time chemical exposure from renovations or a neighbor’s activity.
The human nose can detect acetone at concentrations as low as 20 parts per million, well below levels that cause irritation. So smelling it doesn’t necessarily mean you’re in immediate danger, but it does mean something is releasing chemicals into your air. If the smell is strong enough to cause headaches, dizziness, or throat irritation, ventilate the space immediately by opening windows and leave if symptoms persist. For apartment renters, your landlord is responsible for investigating and fixing refrigerant leaks, mold, and plumbing problems, so document the issue and request a maintenance visit.