The distinctive smell of mothballs comes from one of two chemicals: naphthalene or paradichlorobenzene. Both are solid at room temperature but slowly turn into a gas, releasing that sharp, unmistakable odor into the surrounding air. Your nose can pick up naphthalene at remarkably low concentrations, just 0.084 parts per million, which is why even a single mothball can dominate an entire room.
The Chemicals Behind the Smell
Traditional mothballs were made primarily from naphthalene, a compound derived from coal tar or petroleum. It’s the most volatile member of a family of chemicals called polycyclic aromatic hydrocarbons, and that volatility is exactly what gives it such a strong, persistent scent. Since 2008, naphthalene mothballs have been banned across the European Union and the United Kingdom due to safety concerns, though they remain available in the United States and other countries.
Most mothballs sold today use paradichlorobenzene instead. It produces a similar pungent smell, though some people describe it as slightly sweeter or more chemical than naphthalene. Both compounds work the same way: they release a toxic gas that builds up inside airtight containers, killing clothes moths and their eggs.
Why the Smell Spreads So Easily
Mothballs don’t melt into a liquid before becoming a gas. They skip that step entirely through a process called sublimation, where the solid transitions directly into vapor. At room temperature, molecules on the surface of the mothball gain enough energy to break free and float into the air. This continues steadily until the entire mothball is gone, which is why a fresh box of mothballs placed in spring can shrink to almost nothing by fall.
Because the chemicals become an airborne gas rather than a liquid, they spread quickly through any space that isn’t sealed. In an enclosed closet or storage bin, the vapor concentration builds up high enough to kill insects. In an open room, the gas disperses but remains detectable to the human nose at extremely low levels. Once naphthalene is airborne, it has a half-life of roughly 3 to 8 hours in the atmosphere, meaning it breaks down relatively fast outdoors but lingers in enclosed or poorly ventilated spaces.
Why the Smell Sticks to Everything
Mothball vapor doesn’t just float around a room. It absorbs into porous materials like fabric, wood, paper, and upholstery. The gas molecules settle into the fibers and surfaces of whatever shares the enclosed space, which is why clothing stored with mothballs can smell for weeks or even months after the mothballs are removed. The chemicals essentially become trapped in the material and release slowly over time, creating that stale, recognizable odor long after the source is gone.
Health Concerns From the Fumes
Both naphthalene and paradichlorobenzene are toxic to humans, not just moths. The chemicals can enter your body through inhalation, skin contact, or ingestion. Workplace safety limits cap naphthalene exposure at 10 parts per million over an 8-hour period, though California sets a much stricter limit of 0.1 parts per million, reflecting growing concern about long-term effects.
Naphthalene is classified as a possible human carcinogen by the International Agency for Research on Cancer. Paradichlorobenzene can affect the liver, kidneys, lungs, skin, and central nervous system. Case reports have linked heavy mothball exposure to serious complications including anemia, liver damage, kidney failure, and neurological problems. These extreme outcomes are typically associated with ingestion or prolonged high-dose exposure, but the fumes in a poorly ventilated room are worth taking seriously, particularly for children and pets who are more vulnerable to lower doses.
How to Get Rid of the Smell
Removing mothball odor depends on what absorbed it. For clothing, run a wash cycle using one cup of white vinegar before following up with a second cycle using your regular detergent. For delicate fabrics, soak garments in a solution of eight parts warm water to one part vinegar for about an hour, then rinse. One important detail: make sure the smell is completely gone before putting clothes in the dryer. Heat can permanently set the odor into fabric.
For wood furniture, wipe surfaces with a solution of equal parts water and vinegar and let them air dry. If the furniture has drawers, shelves, or cabinets, place a bowl of coffee grounds or baking soda inside to absorb lingering odor. Both work well, but they need time, anywhere from a few hours to overnight.
Upholstered furniture needs a different approach. Sprinkle baking soda generously over the fabric and let it sit for at least an hour, or overnight for stronger smells. Vacuum it up once it has had time to absorb the odor. You may need to repeat this process more than once.
For closets, wipe down all hard surfaces including shelving and rods with a cleaning solution. Then place bowls of white vinegar, an open box of baking soda, or coffee grounds in the closet, swapping them out every few days until the scent is gone. Cedar chips make a good replacement for mothballs going forward, since cedar naturally deters insects without the toxic fumes.