Is Air Freshener Flammable? (A Comprehensive Overview)

Is Air Freshener Flammable?

Some are flammable and some are non-flammable. Air fresheners come in a wide variety of forms and compositions. Many times their compositions are not fully disclosed. The best recommendation is to prevent the air freshener recipient and the vapor from being heated.

Air fresheners are used in housing, workplaces, schools, cars, among others. Air fresheners are mainly used to give pleasing aromas and/or to inhibit odors.

Usual Chemicals Present in Air Freshener Formulas

Air fresheners come in many different types, but mostly their formulas are made of substances with similar purposes.

  • Fragrances
  • Fragrance carriers
  • Solvent
  • Propellant

The main class of substances that may be present in air fresheners that pose risks for fire are the volatile organic compounds (VOCs). 

VOCs are organic compounds with high vapor pressure (the higher the vapor pressure of a substance the easier it goes to the gaseous phase) and low water solubility, meaning they form vapors with ease and are not easily eliminated by water.

Some of these substances can also react with strong oxidizers such as ozone (ozone is used for some water or air purification procedures).

Fragrances

Responsible for the pleasing aromas. Pretty much all fragrances originate from low weight organic molecules. For instance, limonene gives lemon aroma, cinnamaldehyde gives a cinnamon aroma, both these substances are flammable.

At the same time, however, they are present in very small concentration. By themselves, most fragrance can ignite only in high concentration sprays or aerosol forms.

SubstanceFlash pointExplosive limitsScentChemical formula
Limonene48  ºC0.7% to 6.1%LemonC10H16
Alpha-pinene33 ºCUnknownPineC10H16
Beta-pinene36 ºCUnknownPinesC10H16
Linalool77 ºC0.9% to 5.2%Citric, floralC10H18O
Alpha-terpineol90 ºCUnknownLemon and limeC10H18O

Below the molecules of the above mentioned substances.

Fragrances carrier

Most common fragrance carriers are phthalates, such substances are slightly flammable.

Solvents

Solvents used in air freshener include ethanol and other alcohols, they also are flammable.

Propellants

Propellants are present in sprays and aerosols air fresheners. Propellants include, propellants are often highly flammable substances. Examples of such substances are formaldehyde, benzene, toluene and xylenes.

SubstanceFlash pointExplosive limitsChemical formula
Formaldehyde64 °C7.0 % to 73.0%H2CO
Benzene−11.63 °C1.2% to 7.8%C6H6
Toluene4 °C1.1% to 7.1%CH3C6H5
Xylene isomers17 to 30 ºC~1% to ~7%(CH3)2C6H4

Research on the Hazards of Air Fresheners

A chamber study for the detection of substances in air fresheners was conducted in Germany in 2015 by Uhde and Schukltz. The aim of the study was to identify and quantify VOCs. A series of substances were detected, all of which are least slightly flammable.

In the table below the main chemicals detected along with their masses collected after one hour of emissions.

SubstanceAmount after 1 hourChemical formulaFlash point
Ethanol35,532 μgC2H5OH13 ºC
Limonene 9,132 μgC10H1648  ºC
2-Propanol (isopropanol)5,690 μg(CH3)2CHOH12 °C 
3-Methoxy-3-methyl-1-butanol4,763 μgCH3OCH3C4H7OH71 ºC
Benzyl acetate3,920 μgC6H5CH2COOCH3102 °C
Dihydromyrcenol3,155 μgC10H20O169 ºC
Iso-alkanes3110 μg
Linalool2,994 μgC10H18O77 ºC
Linalyl acetate2,711 μgC12H20O269.6 °C
Gamma-terpinene2,688 μgC10H16183 ºC
Dipropylene glycol isomers2,529 μgC6H14O3~121 ºC
Myrcene 1,679 μgC10H16167 ºC
Beta-pinene1,391 μgC10H1636 °C

It is hard to precisely determine how flammable the air in the ambient with these analyzed air fresheners were. That is because the exact concentration in the air is not given. Complex mixtures such as these cannot have their thermal properties analytically determined.

It is quite likely, however, that right after the initial propagation of the gases propelled by the air freshener is flammable. At times the concentration of VOCs decreases along with the fire hazards.

In another study from 2015 by Steinemann and collaborators emissions from air fresheners in the U.S. were analyzed. The air fresheners included sprays, gels, solids, disks and oils.

The authors found that VOCs, such as acetone, (3-methylbutyl)acetate, limonene, 2,4-dimethyl-3-cyclohexene-1-carboxaldehyde, alpha-pinene, beta-pinene, beta-phellandrene,

carenes, ethyl butanoate, cymene and ethanol were present in at least half of the products.

All of these substances are also flammable and at least 25% of are known to be toxic to humans if inhaled.

Specific Air Fresheners Models and their Fire Hazards

Plug-ins Air Fresheners

Most plug-in air fresheners work by providing heat to oils or other solutions. Fires in the past have been blamed on plug-in air fresheners.

One of the fire hazards is the overheating of the device, either because of malfunction or for remaining on for too long.

The oil that gives off the aromas is composed of complex mixtures, their composition will contain organic flammable substances.

When dealing with plug-in air fresheners it is safer to ensure the product has a proper quality. Some of them are recommended to not be left on for over a certain amount of time.

Avoiding flammable home materials, such as cloth, paper, cotton, wood, near electrical outlets is recommended.

Air Fresheners Sprays

Air freshener sprays can be dangerous if carelessly handled.

This type of air freshener can contain flammable propellants, such as formaldehyde. Some brands use somewhat safer propellants.

The air freshener cans should not be heated or damaged to avoid explosions.

Candle Air Fresheners

The main fire hazard associated with candle air fresheners is the candle flame. The candle wax itself, although considered flammable, does not propagate fire.

The gases produced as the candle burns can be flammable if let to accumulate in an enclosed space.

Bead and Reed Diffusers

This type of air freshener contains essential oils, which are flammable.

Are Air Fresheners Toxic?

Air freshener liberated vastly complex mixtures of compounds. Besides, the composition of each varies by a large margin from different brands, aromas and means of propagation.

It is plausible to assume that most air fresheners contain toxic chemicals in their formulations. The question is what are the chemicals and in what dose they are used.

A general possible hazard is the long term exposure to air fresheners. If inhaled in small amounts for short periods of time air fresheners are unlikely to cause health problems.

Chemicals that give off certain fragrances can cause skin allergies, irritation or rashes.

If in direct contact with the eyes are possible to cause irritation, if any vision is lost a physician should be consulted immediately.

Ingesting air freshener gases, oils or liquids can cause diverse effects as mild as irritation in the mouth or as severe as life-threatening.

Selected Study on the Potential Health Risks of Air Fresheners

A study in 2015 aimed to determine irritative and respiratory effects related with both short and prolonged exposure to indoor pollutants emissions from fifteen selected air freshener products.

The pollutants that were selected for evaluation were acrolein, formaldehyde, naphthalene, delta-limonene and alpha-pinene. 

A Health Risk Assessment was performed in regards to those pollutants.

For all the target pollutants of this study, all the concentration levels obtained were lower than the respective short and long-term critical exposure limits.

For a few products, the measured emissions of formaldehyde were very close to the critical exposure limits.

Some estimates were made which suggested that in some ‘worst case’ scenarios with an extensive use of multiple products can lead to exposure levels beyond the tolerated.

This study was part of the Emissions, Exposure Patterns and Health Effects of Consumer Products in the EU (EU EPHECT project).

Conclusion

The main assessment from the presented text is that air fresheners are extensively varied and the chemicals that compose their formulations are hard to evaluate.

It is clear however that air fresheners may pose a reasonable fire hazard if handled carelessly.

One of the common facts about every air freshener is that they all contain flammable substances in their formulation. However in modern everyday life fire hazards are commonly present.

Frequently Asked Questions (FAQ): Is Air Freshener flammable?

Can an air freshener can explode?

Air fresheners can explode if heated or subjected to naked flames. Explosion risks also exist if the can is damaged.

An apparently empty can also explode, many times small amounts of the formulation may still be present.

Are all aerosols flammable?

Not all aerosols are considered flammable. That depends on what the respective recipient contents.

Are plug-in air fresheners safe?

Overall that depends on the brand and how it is handled. Many contain small amounts of formaldehyde in their formulation that for acute exposure do not pose a significant health issue. On long term exposure they may gradually cause health problems. Some formulations contain naphthalene, there has been research demonstrating that naphthalene can cause damage to lungs of rodents.

At what temperature will an aerosol can explode?

That depends on the can content and the can itself. Heat will cause the liquid and gas inside the can to expand, heat at around 40 ºC can already be enough to cause an explosion, depending on how long the can is kept at this temperature.

Can air freshener catch fire?

Yes, the chemicals commonly present in air fresheners formulations are prone to go through an combustion reaction when heated or exposed to ignition sources.

What happens if you inhale too much air freshener?

Inhalation of small amounts of air freshener may cause mild health issues such as coughing, choking or short breath. Inhaling large amounts of air freshener can cause serious issues. Prolonged inhalation of air freshener can also be of concern.

References

Data regarding the mentioned substances found in:

https://www.osha.gov

Steinemann A, 2015. Volatile emissions from common consumer products. Air

Quality, Atmosphere & Health 8(3):273-281

Uhde E, Schulz N, 2015. Impact of room fragrance products on indoor air quality.

Atmospheric Environment 106:492-502.

https://www.poison.org/articles/air-freshener-171

M. Trantallidi, C. Dimitroulopoulou, P. Wolkoff, S. Kephalopoulos, P. Carrer, EPHECT III: Health risk assessment of exposure to household consumer products,

Science of The Total Environment, Volume 536, 2015, Pages 903-913, ISSN 0048-9697, https://doi.org/10.1016/j.scitotenv.2015.05.123.

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