Naphthalene in the bedroom

At a glance

What it is

Naphthalene is a white crystalline solid at room temperature with a characteristic strong smell detectable at concentrations well below health-effect thresholds. The smell is what most people associate with mothballs — naphthalene was the original ingredient in mothballs and remains in use in many products marketed for that purpose, though paradichlorobenzene has partially displaced it in some formulations.

The chemistry that makes naphthalene distinct among PAHs is its volatility. While benzo[a]pyrene (covered separately on the BaP page) is essentially nonvolatile at room temperature and transfers primarily as particle-bound material, naphthalene readily sublimes and transfers as a vapor. This changes the relevant capture mechanism and the textile-barrier story substantially. For higher-MW PAHs, dust control and fabric filtration matter most. For naphthalene, vapor-phase removal is required.

The compound's IARC Group 2B classification is based on rodent carcinogenicity studies showing nasal and lung tumors at chronic inhalation exposure. The human evidence is more limited but suggestive, particularly for upper airway cancers in occupationally exposed populations. Beyond carcinogenicity, acute naphthalene exposure can cause hemolytic anemia (particularly in people with G6PD deficiency), and the compound is a documented respiratory irritant at higher concentrations.

How it gets to the bedroom

From mothballs and moth repellents

Mothballs are the most concentrated direct source of bedroom naphthalene. Even when stored in closets or drawers, the vapor migrates into bedroom air continuously. The smell is the exposure signal: if you can smell mothballs, you are inhaling the compound at concentrations of toxicological relevance. Closets and drawers in bedrooms with mothball use have measurably elevated air concentrations compared to other rooms. Peer-reviewed

From firefighter occupational exposure

Naphthalene is among the compounds tracked in firefighter PAH exposure studies. The firefighter PPE workplace protection factor for naphthalene specifically is 3-10 — meaning the gear reduces exposure but does not provide complete protection, particularly for the vapor-phase component. Peer-reviewed — PMID 38560919 The compound off-gasses from contaminated turnout gear after fire events, similar to the benzene off-gassing documented in Fent 2015.

From cooking and combustion

Char-grilling, broiling, and other high-temperature cooking produce naphthalene along with the broader PAH mixture. Restaurant exhaust has been measured at substantial concentrations; residential cooking contributes proportionally smaller amounts. Wood-burning stoves and fireplaces are residential sources. Cigarette smoke contains naphthalene; thirdhand smoke surfaces release naphthalene as part of the broader VOC re-emission.

From motor oil, asphalt, and petroleum products

Used motor oil contains substantial naphthalene; mechanics' clothing and home garages where oil is changed are sources. Asphalt sealants used for driveways off-gas naphthalene for weeks to months after application. Vehicle exhaust contains naphthalene as part of incomplete combustion products.

Vapor-phase transfer through bedding

Unlike higher-MW PAHs, naphthalene's vapor pressure is high enough that it diffuses freely through cotton bedding. The 2024 cotton sheet permeation study established that workplace protection factor through cotton textile is approximately 1.0 for volatile aromatics, including naphthalene at the smaller end of the PAH spectrum. Peer-reviewed — PMID 38560919 This means naphthalene in bedroom air reaches the sleeping body's breathing zone essentially unimpeded by bedding.

What the research says

Documented health effects

The IARC Group 2B classification reflects rodent carcinogenicity evidence showing nasal and lung tumors at chronic inhalation exposure, plus limited human evidence for upper airway cancers in occupationally exposed populations. Peer-reviewed Beyond cancer, acute naphthalene exposure causes hemolytic anemia particularly in people with G6PD deficiency (which affects approximately 400 million people globally). The compound is metabolically activated to reactive intermediates that cause hemolysis of red blood cells.

EPA's reference concentration for chronic inhalation exposure is 3 µg/m³ — a level that mothball-using households frequently exceed.

Bedroom-specific evidence

Mothball-using households have been measured at indoor naphthalene concentrations frequently exceeding the EPA reference concentration. Peer-reviewed Non-mothball households typically have residential naphthalene concentrations in the 1-3 µg/m³ range. Households with attached garages where vehicles are stored or where motor oil is handled have elevated concentrations.

For firefighter populations

Firefighter occupational naphthalene exposure has been documented through the broader PAH monitoring programs. The relatively low WPF through turnout gear (3-10 versus essentially 1.0 for benzene) means PPE provides meaningful but incomplete protection. Contaminated gear off-gasses naphthalene continuously post-event.

For people with G6PD deficiency

G6PD deficiency is one of the most common enzyme deficiencies globally and is particularly prevalent in people of Mediterranean, African, and Southeast Asian descent. People with G6PD deficiency are at elevated risk of hemolytic anemia from naphthalene exposure. Mothball exposure in particular has been documented to produce acute hemolytic crises in this population. Peer-reviewed This is one of the cases where individual genetic context substantially changes the risk assessment from population averages.

What helps reduce exposure

Eliminate mothballs from the home. This is by far the highest-impact single intervention for residential naphthalene exposure. Alternative moth repellents (cedar wood, lavender, herbal sachets, vacuum sealing for off-season clothing storage) are available and meaningfully effective for textile pest control without the carcinogenicity profile.

Ventilate the bedroom with fresh air. Naphthalene concentration declines linearly with air exchange rate. Bedrooms with windows opened regularly have lower accumulated concentrations than sealed rooms.

For firefighter households: gear management protocols. Same as for other PAHs — gear storage away from sleeping areas, post-shift showering, and avoidance of take-home contamination of bedrooms all reduce exposure.

Activated carbon air filtration. Naphthalene is one of the more readily captured compounds in residential air purifier applications. Granular activated carbon adsorbs the compound effectively; the vapor-phase chemistry means capture must run continuously rather than just addressing particle-bound contamination.

Eliminate or vent residential combustion sources. Wood-burning stoves and fireplaces are residential naphthalene contributors. Range hood ventilation during cooking reduces the cooking-source contribution. Outdoor venting of wood-burning combustion eliminates indoor concentrations from that source.

For people with G6PD deficiency: heightened precaution. Direct skin contact with mothballs or naphthalene-treated clothing has triggered acute hemolytic crises in G6PD-deficient individuals. If you have G6PD deficiency (or have a family member with it), naphthalene exposure reduction is more urgent than the general population recommendations suggest. Speak with a clinician about appropriate protocols if you have ongoing exposure concerns.

What does NOT help

• HEPA-only air purifiers. HEPA captures particles; naphthalene transfers and exists primarily as a vapor. HEPA-only filtration does not address naphthalene meaningfully.
• Cotton bedding as a barrier between bedroom air and the breathing zone. The cotton sheet permeation studies establish that volatile aromatics including naphthalene transfer through cotton essentially unimpeded.
• "Paradichlorobenzene-based mothballs" as a safer alternative. Paradichlorobenzene (PDCB) is classified by IARC as Group 2B (possibly carcinogenic to humans) and produces similar concerns to naphthalene. Both mothball formulations are exposure sources warranting elimination from residential environments. Regulatory
• "Airing out" mothball-using closets occasionally. The compounds continue subliming as long as the source material is present. Ventilation reduces accumulated concentrations temporarily but doesn't address the source.

Open research questions

• The contribution of off-gassing from contaminated firefighter gear to residential naphthalene exposure in firefighter households. Speculation
• The capture efficiency of activated carbon at the sleep-surface interface for vapor-phase naphthalene, particularly under body-warmed sleep conditions. Speculation
• The dose-response for upper airway cancers in chronic low-level residential naphthalene exposure. Peer-reviewed mechanism; speculation on residential dose-response

Citations

1. IARC. Naphthalene Group 2B monograph. Peer-reviewed
2. EPA. Integrated Risk Information System (IRIS) — Naphthalene. Regulatory
3. ATSDR. Toxicological Profile for Naphthalene. Regulatory
4. National Toxicology Program. Naphthalene Technical Report. Peer-reviewed
5. Stratan A et al. (2024). Workplace protection factor of firefighter PPE for aromatic VOCs. PMID 38560919 Peer-reviewed
6. Fent KW et al. (2015). Contamination of firefighter personal protective equipment and skin. DOI 10.1080/15459624.2015.1025135 Peer-reviewed

Frequently asked questions

• If I can smell mothballs, is that dangerous?

  The smell threshold for naphthalene is in the same concentration range as toxicologically relevant exposure levels. If you can smell mothballs in your home, you are inhaling the compound at concentrations that exceed EPA's chronic inhalation reference concentration in many cases. The smell is the exposure signal — if you smell it consistently, exposure is occurring at meaningful levels.

• Are cedar blocks or lavender sachets effective alternatives to mothballs?

  For textile pest control, cedar wood, lavender, and herbal sachets are moderately effective at deterring moths and carpet beetles. They are not as potent as naphthalene or paradichlorobenzene but they are also not classified as possible carcinogens. For seasonal clothing storage, vacuum sealing in plastic bags (regardless of any herbal additions) is one of the most effective pest-prevention approaches and eliminates the need for chemical repellents entirely.

• Why is naphthalene different from other PAHs?

  Its small molecular size and high vapor pressure. While most PAHs (benzo[a]pyrene, pyrene, others) transfer primarily as particle-bound material and require particle filtration for removal, naphthalene transfers as a vapor. This changes both the relevant capture mechanism (vapor-phase adsorption rather than particle filtration) and the textile-barrier story (cotton bedding doesn't impede vapor transfer).

• Should I worry about naphthalene from cooking?

  Residential cooking produces naphthalene, particularly char-grilling and high-temperature broiling. The contribution to total residential naphthalene exposure is typically modest compared to mothballs or attached-garage sources. Range hood ventilation during cooking and outdoor cooking when feasible reduce this pathway.

• Can I test for naphthalene in my bedroom?

  Yes — indoor air quality assessments by certified industrial hygienists can quantify residential naphthalene concentrations. Less expensive consumer-grade VOC monitors don't typically distinguish naphthalene specifically. If you suspect a mothball source or have ongoing health concerns, professional indoor air testing is the more reliable path to specific concentration data.

Related compounds

• Benzo[a]pyrene — the higher-MW PAH most directly tied to cancer outcomes in firefighters
• Pyrene — four-ring PAH; ACGIH BEI compound via 1-hydroxypyrene biomarker (coming soon)
• Benzene — single-ring aromatic; IARC 1; similar firefighter PPE penetration story

Embr Sleep is a sleep environment company researching and addressing the chemistry of the bedroom. Our PAH work focuses on capture at the sleep-surface interface, including the vapor-phase component that simpler PAHs like naphthalene introduce. Research and product development in progress.

Last reviewed 2026-05-15. If you find a factual error, contact us.