Luna moth (C) Daniel FriedmanMothball Odor Hazards
Health risks of Mothballs: naphthalene; removal of naphthalene odors

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Mothball or naphthalene odor removal & mothball chemical & gas hazards:

The US EPA estimates that about 7.5 million pounds of naphthalene are marketed in the U.S. each year as a pesticide, of which the major use is in moth repellant products. (US EPA 2008).

Here we describe the detection of and risks of exposure to mothball chemicals & odors when moth repellent products are applied indoors in buildings.

We describe how to get rid of mothball odors in buildings, building furnishings, clothing, or vehicles.

We note the possible health hazards from exposure to mothball odors (and gases) as well as the child hazard of eating mothballs or moth repellent products. We discuss methods to reduce mothball chemical & gas exposure.

We cite authoritative sources of information about safe and proper use of moth repellents and about mothball and moth repellent chemistry, child hazards, indoor air quality and health concerns, and proper application and use of these products.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Mothball Odors & Chemicals, Hazards, Exposure, Health Effects, Odor Removal

Moth (C) Daniel FriedmanMothballs are fumigants containing naphthalene or paradichlorobenzene and act a pest repellent and possibly act also as a pesticide used to protect clothing and other soft goods from attack by moths.

Naphthalene has been used as insecticide world wide since about 1880 (Pyenson 1936), but its health effects, also discussed here, were studied a bit later, beginning around 1900 (Nash 1903).

The moth at left and all other moths shown in this article except the one at the top of this page are not clothes-attacking insects.

[Click to enlarge any image]

But the naptha fumes from mothballs can both penetrate and be very persistent in carpets, fabrics, even wood and drywall as well as other materials.

Such mothball smells or fumes may pose a respiratory hazard to some people, can be difficult to remove, and can even interfere in the sale of a mothball-smelling property. (New York Times 2017/11/08)

Article Series Contents

Some people have also tried using moth repellent products like mothballs to keep rodents and other pests out of certain building areas or out of stored vehicles.

Enos Para Mothballs at InspectApedia.comPlacing an open box of mothballs under the hood of my MG midget while it was stored kept squirrels and mice from nesting in the engine compartment, and leaving a box of mothballs inside the car was an attempt to keep the same pests out of the vehicle interior too.

Watch out: we do not recommend placing mothballs, moth cakes, or moth repellent flakes inside building rooms, crawl spaces, attics, wall or ceiling cavities, trash cans, nor inside vehicles, both because the fumes and chemicals can be hazardous to humans and because the odor can later be difficult to get rid-of. We explain this problem in detail below.

Watch out: because mothballs are a registered pesticide and because of the toxicity of their chemicals, it is illegal to use mothballs or moth crystals, cakes, etc. as a repellent for animal pests (birds, cats, deer, dogs, moles, pigeons, mice, skunks, raccoons,snakes, squirrels, etc.) [19]

Some sources such as the U.S. California state department of Pesticide Regulation says that mothballs in fact do not repel rats, mice, nor moles.

However the use of naphthalene as an animal pest repellant was included in the US EPA's description of that material in its 2008 Registration Eligibility document cited below. (US EPA 2008)

In the U.S. the EPA permits use of moth balls to repel moths and caterpillars only. Because moth balls are toxic to humans and pets mothballs are not permitted for use in buildings to repel animal pests like squirrels or bats.

Luna moth (C) Daniel FriedmanAs stated in Best Practices Guide to Residential Construction and detailed


Pesticides are a special class of organic chemicals designed to kill living organisms.

In addition to the compounds used in the home and garden, the class of chemicals regulated as pesticides also include kitchen and bath disinfectants, flea and tick products, and swimming pool chemicals.

In most cases, both the active ingredient targeted to one or more pests and the “inert” carriers are organic chemicals that are toxic to humans.

Every registered pesticide has a “signal” word on the label, ranking the level of toxicity to humans, as follows:

Page top image of mothballs courtesy of Wikipedia creative commons. Clothes moth image shown at above left is from Stone & Stock, PNW who provide an excellent guide to moth control. [19]

Health Effects of Exposure to (or ingestion of) Mothballs, Moth cakes, Moth Repellent Crystals

Fig tree "moths" - central Mexico (C) Daniel FriedmanMothballs contain either of the chemicals paradichlorobenzene or naphthalene. Paradichlorobenzene is classified as a possible human carcinogen by the EPA, and its vapors can irritate skin, eyes, and the respiratory tract.

Large doses can damage the liver. Mothballs are not intended to be placed in open spaces such as rooms, closets, or vehicles. Rather they should be used in an airtight space such as a clothes storage bag. [7]

Mothballs are fumigants that will dissolve or sublime at lower temperatures; mothballs thus work by a process of sublimation - the solid ball of chemicals converts directly to a gas that enters the air nearby. [2][7]

But believe it or not mothballs or moth crystals may also be a child hazard if eaten - as has happened. [3][6][7]

Symptoms of exposure to naphthalene include headache, nausea, dizziness, and difficulty breathing. Paradichlorobenzene is also a potential hazard, although typically less so compared to naphthalene. .

Eating just one mothball containing naphthalene can damage a young child’s red blood cells.... [7]

Exposure to naphthalene promotes hemolytic anemia, associated with fatigue in mild cases and acute kidney failure in severe cases. Poisonings of infants have been reported after dressing the children in clothing stored in naphthalene mothballs.

Below: an edited (excerpted) page from a 1963 Boys Life magazine describing a do-it-yourself home science project using moth balls, water, baking soda, and vinegar.

1963 Science Project using mothballs,Boys Life Magazine - edited - at

Watch out: we do not recommend repeating this experiment unless under supervision of your science teacher or another suitable expert.

Mothballs are a particular hazard to children, especially small children who may mistake a mothball for something edible.

FYI for our Australian readers, there have been recent news reports inquiring if mothballs are harmful to babies - we're researching that question.

Certainly eating sucking on mothballs, and probably exposure to high levels of mothball offgassing can be harmful to babies and mothball odors can trigger problems for people with allergies and asthma (including this site editor). (Sudakin 2011).

Dawson back in 1958 documented this concern: it's certainly not "new" news.

Watch out: at TERMITES & NAPTHALENE HAZARDS we point out that there can also be naturally occurring sources of naphthalene in buildings. These too might be at a sufficient concentration to pose a health hazard.

How to Reduce Indoor Exposure to Mothball Odors, Chemicals, Gases

Fig tree "moths" - central Mexico (C) Daniel Friedman
  1. Avoid unnecessary use of mothballs & moth repellents: When possible, the best approach is to find non chemical approaches to pests, including moths. That includes
    • Don't use moth repellents if you don't have a moth problem in the first place. Moth larvae are shiny light colored wormlike organisms about 1/2-inch in length. Adult clothing-eating moths are white

      (Image at left, PNW) [19]

      Don't blame the innocent. None of the other moth or insect pictures shown in this article are clothing-eating insects.

      To check for a moth infestation in your home, and keeping in mind that most moths are not the species that attack fabrics, you can try a pheromone trap to monitor for moth activity.[2] The insects shown in our photo (left) attack our fig plant but not our clothing.
    • Avoid importing moths, moth pupae or moth larvae (it's the larvae that eat animal fibers and fabrics) by cleaning used or old clothing that is "new" to your home before storing those materials away
    • When storing clothing or other soft goods, especially woolens or other animal fiber materials, use clothing storage containers that are dry and airtight, first to keep moths out, and second, especially if moth repellent products are to be placed therein, to prevent mothball odors from invading other building areas or materials.
    • Do not simply place moth repellent products in open boxes in areas such as rooms, closets, garages, or vehicles in an attempt to keep them moth (or mouse, or squirrel) free.
    • Cedar closets? cedar fumes are toxic to moths only at high concentrations. Don't trust a cedar closet alone to prevent moth damage, although indeed cedar wood and cedar oils do avoid the mothball hazard and odor issue.[2]
    • Dried lavender and cedar fiber balls as moth repellents are not supported by good evidence. [2-Farr]
  2. Wash or dry clean clothing before putting it into storage; clean clothes are less attractive to moths according to some experts. Moth eggs, moth larvae as well as adult moths can all be killed by a hot water wash cycle.

    Moth eggs, pupae, or even adults may already be present in clothing, including cotton even though which moths are not directly attracted to that material. Dry-clean wool or other animal fiber materials (to which moths are attracted) for the same reason. [2]

Moth repellents - older packaging (C) Daniel Friedman at Moth repellents - older packaging (C) Daniel Friedman at

Shown here: older "moth-proofing", moth blocking, and moth repellent products from Fuller Products and Avon Products.

  1. Read the mothball package label and closely follow instructions. If you are going to use a moth repellent product like mothballs, read and follow the directions on the product label.

    Watch out: Keep these products away from children who may be especially vulnerable not only to vapors from mothballs but as something sometimes eaten.

    Watch out: also, some of the moth proofing products shown here are self-describd as flammable and must be used only as directed.
  1. Dispose of unwanted mothballs safely. Most of these chemicals contain VOCs that will vaporize and get into the household air. If you cannot dispose of partially used containers, store outside the living space.
  2. Minimize exposure to moth repellant products. When used,place mothballs, moth repellent cakes or moth crystals in a well-sealed trunk or other container that can be stored in ventilated areas outside of the main living space, such as attics or attached garages.
  3. Minimize exposure to some air fresheners: Paradichlorobenzene is also the active ingredient in many air fresheners and should be avoided.

Yellow caterpillar (C) Daniel FriedmanReader Question: How can we get rid of an annoying mothball odor in our Condo?

We moved into a condo, which is a concrete block structure 3 months ago. Shortly after the move we began to smell moth balls.

After following the smell we were able to find out that the unit above us displaced several moth balls throughout there unit, tightly sealed the unit up without air conditioning on(we live in Florida) and left for the summer.

As the smell increased in our unit we begged parties involved to rid the unit of the moth balls and air it out.

Finally this was done, however even though the smell appears to be gone sometimes, other times we can still smell a bad odor, sometimes now the odor is less mothball smell and just simply a bad odor.

We have tried everything and are desperate to solve the problem. Is it possible to get rid of this toxic odor?

Any help would be greatly appreciated. - B.P. 9/22/2012

Reply: How to get rid of mothball odors in buildings, contents, clothing, furnishings

Insect wing scales (C) Daniel FriedmanIndeed the odor from mothballs is a VOC-like substance (paradichlorobenzene or naphthalene) that quite penetrates many materials including even drywall, furnishings, carpeting, and it can take quite a while for it to diminish.

And most people can smell mothballs - the characteristic odor of those chemicals can generally be detected in air at a concentration of just a few parts per billion, so getting rid of mothball odors is going to take some thorough airing out and cleaning.

  1. Airing out the original building area helps, this means opening windows and perhaps even using fans to move a good volume of fresh air through the building area - weather permitting.

    This is the best and principal means of reducing indoor mothball odors in building spaces themselves, and it will help reduce odors from furnishings and carpets and draperies too.
  2. Find & address the principal odor source: in general, odor removal of any sort in buildings is most effective if we can identify the exact odor source and remove or clean or seal that source. - what materials absorbed the gases, airborne compounds or VOCs from the mothballs - perhaps using

    our SMELL PATCH TEST to FIND ODOR SOURCE - and then try sealing those surfaces if the smelly materials are not something that can be disposed-of.
  3. Turning up the heat in the space where mothball odors persist can help drive volatiles back into building air where in combination with fresh air venting you will reduce mothball odors.

    For soft goods such as upholstered couches you may speed up the mothball odor removal by using a hair dryer (on low or medium temperature) to heat the upholstered surfaces.
  4. For soft goods such as clothing that has absorbed mothball odors, having the clothes dry-cleaned or laundered, or sometimes simply running washable clothing through the clothes dryer on medium heat will suffice to get rid of the mothball odors.

    If that doesn't solve the problem and you need to go further you'd need to track down the principal sources of the odor
  5. Watch out: for mothball odor solutions that are ineffective, are products sold by someone with a conflict of interest, or may in fact make matters worse as we note in the following items in this list.
  6. Ozone generators for mothball odors? Do not try using ozone or an indoor ozone generator to get rid of mothball odors. Improperly used you will find you've made a worse problem than before.

    See OZONE MOLD / ODOR TREATMENT WARNINGS for details and for links to articles that describe how over-treatment by ozone can generate new horrible, costly-to-remove odors in buildings.
  7. Activated charcoal to "remove" mothball odors ???

    In our OPINION the recommendation by some sources to place activated charcoal in the space where the mothball odors are strong is not likely to be useful; air circulation and fresh air are more effective than relying on a passive absorption system that never addresses the source of odors.
  8. Air purifiers to remove mothball smells?

    In our OPINION, a portable indoor "air purifier" is unlikely to move enough air through a charcoal filter to be effective except in the case perhaps of a very small enclosed space.

    Unfortunately some key studies we have reviewed tested a portable air "purifier" by placing it into an enclosed chamber with a limited amount of a specific pollutant - not a realistic nor real-world situation.


Life Expectancy of Mothballs Used in Buildings, Mothball Sublimation Rate, Mothball Odor Persistence

Napthalene moth balls for sale at an online store (C)  notice: this website does not sell any product nor servicveOn 2017-07-27 by Laurie Davis - What is the life expectancy of a moth ball in a hot area?

What is the life expectancy of a moth ball in a hot area? How long does it continue to release the harmful fumes?

On 2017-07-27 by (mod) - Life Expectancy of Mothballs Used in Buildings - Mothball Sublimation Rate


If you will permit me to wave my arms about mothball sublimation rates as a preface to giving an opinion about how long a mothball will "last" in use then my estimates of mothball life will, perhaps, make more sense.

Tennakone (1978) looked at the sublimation rate for mothballs - but I've not yet gotten a copy of the full article to support the following opinion with science.

Mothballs exposed to the open air will be seen to shrink in size, eventually disappearing, following a process called sublimation: the solid (mothball) converts to a gas without ever entering an intermediate liquid state.

The rate of sublimation of mothballs is determined principally by the amount of air available to or circulating around the mothball.

That's because the sublimation rate of mothballs depends on the relative naphthalene gas or para-dichlorobenzene vapor pressure difference between the thin layer of air at the surface of the mothball and the surrounding air.

When mothballs are kept in a small sealed container or relatively-airtight bag (as they are in a sealed box of mothballs in the store), the gas vapors are trapped around the mothballs, slowing their rate of sublimation to almost nothing.

But when the same mothballs are spread about in more-open air the vapor pressure differences of the mothball gases permit them to continue to off-gas into the surrounding area.

Mothballs that are actually in the spherical form, about 1/2" in diameter when new, will last from a month to several years or longer depending the type of mothball and on how they are placed.

Furthermore the life of mothballs depends on the product chemistry: naphthalene mothballs take much longer to dissipate than mothballs comprised of para-dichlorobenzene.

Moth, Costa Rica April 2018 (C) Daniel FriedmanPhoto: A moth photographed by the author on the Osa Peninsula, Costa Rica, in 2018.

For example based on simple experiments and observations of mothballs I've placed in buildings, closets, bureaus, or kept in closed packages, I estimate that:

In a hot area like an attic where convection currents may be moving more air about, those mothball life expectancies will be less due to the effects of both temperature and air movement or air velocity on the sublimation rate of the mothballs of either formula. Moisture might also be a factor in the the rate of mothball sublimation.

"In air, the half-life of naphthalene and paradichlorobenzene is less than one day and about 31 days, respectively." (Fishel 2014) [1] at REFERENCES.

But that half-life expression is misleading. It would only be accurate if we could obtain a measured volume of these two gases ALONE, that is, without a source that continues to emit them, and if we could then obtain more specific information about the concentration of those gases in the space and the rate of fresh air ventilation of the space as well as quite a few other factors.

Watch out
: however the fumes from these gases may permeate and remain in clothing or building materials after the actual mothballs or moth crystals have dissipated.

Differences Between Paradichlorobenzene Mothballs & Naphthalene Mothballs

Enos Para Mothballs at Enoz napthalene mothballs at

Above are two different moth ball products sold by Enoz®. Enoz® Paradichlorobenzene moth balls and Enoz® "old fashioned" or naphthalene mothballs.

These two mothball substances are chemically different, have different properties.

Naphthalene mothballs produce an off-gassing (through sublimation) that creates and environment that repels moths as well as some other creatures. Naphthalene mothballs, and the odor they produce, remains in the environment of use longer than Paradichlorobenzene mothballs.

That is, it will take longer for the Naphthalene odor to dissipate even when the mothball source has been consumed or removed.

Paradichlorobenzene mothballs produce less noticeable odor (to humans) and its gas will dissipate in free air more quickly than the offgassing product of Naphthalene mothballs.

According to Enoz®, "Para" mothballs for clothing are approved by the Environmental Protection Agency and sport EPA registration number: 1475-39

If all other parameters are the same (air movement, temperature, etc), Paradichlorobenzene mothballs produce a higher-concentration of gas in the treatment area than Naphthalene mothballs, possibly increasing the effectiveness of Paradichlorobenzene for the murder or at least the discouragement of moths. [10] at REFERENCES

Mothball & Other Odors' Impact on Real Estate Sales

Avon Moth repellents - older packaging (C) Daniel Friedman at Avon Moth repellents - older packaging (C) Daniel Friedman at Avon Moth repellents - older packaging (C) Daniel Friedman at

[Click to enlarge any image]

Termites & Other Natural Sources of Naphthalene: Possible Hazards to Humans

Termite damage photographs (C) D Friedman D GrudzinskiFirst reported by Chen in 1998, termites produce naphthalene (NPH) or possibly other volatile chemicals (fenchone) or polycyclic aromatic hydrocarbons (PAHs) , as an insect repellent, in the course of building mud tubes and termite nests, including termite infestations in the wood components of some buildings. (Chen 1998, Bandowe 2009, Wilcke 2000).

Etymologists pose that a "natural" production of naphthalene by termites has the function of protecting the termite colony from their predators including some species of ants, bacteria, soil fungi, and microscopic nematode worms.

When a building has suffered significant termite infestation and damage, is it possible that the human (or other animal) occupants of the building will be exposed to significant naphthalene gases in building air without ever realizing that such exposure is taking place?

Possibly. (Though in our opinion and based on research to date, probably not).

Really? Termite-produced naphthalene off-gassing in buildings has been posed, somewhat speculatively in our opinion, as a health risk for people.

Researching termite and other natural sources of naphthalene in buildings, we found research confirming that naturally-generated naphthalene in termite nests, particularly formosan termite nests, occurs.

Naphthalene in termite tests probably serves to benefit the termites by discouraging the growth of some fungi and possibly by discouraging nematodes or other worms.

However we have not found scholarly nor other authoritative research documenting that the (probably trace-) levels of naphthalene that might be produced by termites infesting as building have actually been found to cause human illness.

Watch out: other human illnesses that might correlate with termite or other wood destroying insect infestation in buildings could include irritating airborne particles causing or contributing to asthma attacks, and pesticide poisoning from amateur or improperly-applied chemicals or pesticides in or around the building.


Other natural sources of naphthalene can include Muscodor vitigenus, an endophytic fungus (Daisy 2002).


Termite & Other Natural Sources of Naphthalene in Buildings

Termite identification sketch (C) Daniel Friedman

Symptoms of Napthalene Poisoning

When naphtalene is inhaled the chemical is stored in the human (or animal) body fat cells. In this phase of exposure the building occupants may not show symptoms of naphthalene poisoning. However should the building occcupants later lose weight for any reason, the body's shift to burning fat cells can release napthalene into the circulatory system, causing napthalene poisoning.

That humans can suffer serious illness in response to napthalene exposure has been known since at least 1903, and in 1949 Zuelzer cited acute heolytic anemia due to napthalene poisoning. (Nash 1903, Konar 1939, Zuelzer 1949).

More extreme napthalene poisoning can produce these symptoms:

Health Hazards of Breathing Mothball Offgassing or of Eating Mothballs: Naphthalene Poisoning


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Or see MOTHBALL ODOR HAZARD FAQs questions & answers about mothballs posted originally at this article.

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