Carpet/Rug/Upholstery Cleaning

Combating Mothball Odor

Every year, we get calls from cleaners or consumers wanting to know what to do about mothballs or flakes that were used in excess.

Every year, we get calls from cleaners or consumers wanting to know what to do about mothballs or flakes that were used in excess. Usually, these situations evolve from fear of damage that might be caused by moths, beetles, silverfish that feed on protein fiber in silk or wool clothing or rugs.  They also are used in attempts to keep squirrels, snakes or other non-domesticated animals out of attics or crawlspaces.

Where a few mothballs or flakes would do the job, these well-intended but overzealous consumers toss in two or three boxes of the material. 

Whoa!  Talk about odor!

High concentrations of mothball vapor can cause respiratory irritation.  Ingesting mothballs, especially by small children, can cause serious illness or even death. 

When consumers can no longer tolerate the overwhelming mothball odor, they usually call a professional, who’s supposed to have a magic bullet for relief.  Tain’t that simple! 

So what’s in mothballs? 

The original chemical used for mothballs is naphthalene, a combustible dry solvent.  An alternative formula for mothballs contains 1,4 dichlorobenzene.  Both produce the strong “mothball” odor.  Some formulas even contain a little camphor, which has been used as an insect repellent for years.  The vapor released from mothballs over time as they sublimate (change from a solid to a vapor without going through a vapor phase) can kill insects, silverfish, larvae or other small pests. 

So just what does a professional deodorizing technician do when excessive mothball odor is encountered?  Before discussing procedures, let’s go back to the basic principles of deodorizing…again!

Remove the source as practical.  Collect the mothballs that are lying around or vacuum up moth flakes or crystals, as practical. 

Clean surfaces affected by direct contact with the mothballs, as practical.  Basically, a general purpose cleaner or “wall-washing” formula, with a little fragrance added, will do the job of cleaning minor residue from mothballs.

Recreate the conditions of odor penetration with an appropriate odor counteractant.  Since mothballs are organic chemicals, ozone gas is especially appropriate for use here. 

Seal surfaces as required.  Seldom do we have to employ this principle, but it should at least be considered.  All four deodorizing principles should be very familiar to professional cleaners or restorers by now.  Actual procedures for mothball odor include, but are not necessarily limited to:
  • Communicate with property owners to ascertain exactly how the mothball application occurred.
  • As an engineering control, ventilate the affected area.  Don’t hesitate to uses vent fans in the structure as well and, weather and security permitting, open windows and doors as appropriate.  If it isn’t practical to open affected areas for ventilation, use a negative air machine (NAM), which exhausts to the outside of the building to produce negative pressure within the work area and confine the odor. 
  • If the affected area is one or two rooms in a house, it may be prudent to contain that area with four-mil polyethylene plastic sheeting, and place the containment under negative pressure. 
  • Protect yourself.  Neoprene gloves and an organic vapor respirator, at a minimum, are appropriate. 
  • Considering deodorizing principle one above, collect and remove all the mothballs you can locate, or vacuum up flakes or crystals.  It’s a good idea to exhaust the vacuum outside the work area, since air passing through the vacuum will increase odor in the work area.  Of course, empty the vacuum’s collection bag or chamber soon after vacuuming is complete. 
  • It may even be prudent to remove affected insulation in attics, or on ground soil in crawlspaces when moth flakes or crystals are used extensively.  Use professional judgment here.
  • Consider cleaning affected and surrounding surfaces (e.g., walls, fixtures, flooring – especially carpet) in the affected area, as appropriate.  A general-purpose cleaner or wall washing compound with general-purpose deodorant added can be used on minimally or non-porous surfaces, and fabrics can be cleaned with appropriate cleaners as well.  Hot water extraction is recommended on fabrics.
  • Air out the area, turn off vent fans and, after about 30 minutes, “sniff out” the area to see if the mothball odor has been diminished. In severe odor situations, it may be prudent to confine the area and set up an ozone generator for 24-48 hours.  Mothball odor is organic and ozone is a powerful oxidizer of organic malodor.  Remember that mothballs produce a chemical odor, rather than microbial odor, so sanitizers or disinfectants will be of little use here.
  • After appropriate time, turn off the ozone unit and aerate the area for 10-20 minutes.  Then, turn off vent fans and close up the area for 20-30 minutes.  At that point, technicians should enter and “sniff out” the area to see if the odor has diminished.
  • If the mothball odor persists, continue with ozone application, followed by ventilation and evaluation until the odor level is acceptable.  Eventually, this odor will dissipate. 
  • Depending on the time of the year (summer or winter), an alternative or supplement to using concentrated ozone is to ventilate the area continuously for a few weeks until the mothballs sublimate or dissipate completely.  Obviously, hot weather conditions speed sublimation, while cold weather slows it.  But continuous ventilation is the key to success here.
  • When the mothball odor is substantially diminished or eliminated completely, it may be appropriate to leave a time-release deodorant in the structure’s HVAC system to provide a pleasant residual fragrance.

Probably the greatest source of concern and expense for consumers is damage caused by moths on high-value wool or silk area rugs.  There are time-tested chemical compounds designed to inhibit and retard wool disintegration from organic sources, such as moths or beetles.  These products (e.g., Fabpro’s Wool Protector) contain magnesium silicofluoride, which is a poison.   However, deodorizing technicians should not make claims about these products’ ability to act as a pesticide.  Pesticide claims require government testing and registration, which is a prolonged and expensive process. 

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