Mothballs in the U.S. contain high concentrations of either naphthalene or paradichlorobenzene. Both active ingredients are solid chemicals that slowly become fumes at room temperature. The fumes kill clothes moths when trapped inside sealed containers. Mothballs slowly disappear as they turn into gas and mix with the surrounding air. The time it takes a mothball to vaporize depends on many factors, including how many mothballs are present, the amount of air-flow around the mothballs, and the temperature.
Mothball fumes can stick to fabrics or clothing following storage, requiring items to be aired out and washed to remove the odor. Mothballs are not intended to be used outdoors as the ingredients can contaminate plants or soil, harm wildlife, contaminate water supplies and contribute to air pollution.
For more detailed information on the environmental fate of mothballs, see the additional resources listed below. If you have questions about the chemicals in mothballs, or any pesticide-related topic, please call NPIC at 1-800-858-7378 (8:00am - 12:00pm PST), or email at firstname.lastname@example.org.