What Gases Do Paraffin Candles Release When Burning?

Candles can help create a warm, relaxing atmosphere and add a decorative touch to any space. Paraffin wax candles are common options found in many homes. But what gases do these candles give off when burning? Understanding candle emissions provides insight into the impacts on indoor air quality and health.

Overview of Paraffin Candles

Paraffin wax comes from petroleum. It’s a soft, colorless wax made from saturated hydrocarbons. Paraffin has a low melting point, making it an economical choice for candle making. Its moderate burn temperature and opacity also make it suitable to incorporate dyes and scents. The soot it produces helps anchor fragrances. While not the most natural option, paraffin is affordable, widely available and compatible with candle production methods. It remains the most common candle wax today.

When a paraffin candle burns, the wax liquefies as it reaches its melting point of around 130 to 200°F. This allows the wick to absorb and ignite the wax vapor. This exothermic reaction gives off light, fragrance and a complex mixture of emissions. But with paraffin derived from a non-renewable petroleum source, it raises environmental and health concerns.

Major Gases Released When Burning Paraffin Candles

Carbon Dioxide (CO2) – All burning candles produce carbon dioxide. It’s a byproduct of the chemical reaction when the hydrocarbon wax combines with oxygen. Paraffin wax contains many carbon atoms, which break apart as CO2 when burned. This greenhouse gas is not directly toxic in typical concentrations from candle use. But it can contribute to poor indoor air quality and health complaints.

Water Vapor (H2O) – As paraffin and the wick combust, hydrogen atoms released combine with oxygen to form water vapor. This can add noticeable humidity to a room, though not as significantly as activities like cooking or showering. The water vapor emissions are not a health hazard.

Carbon Monoxide (CO) – Incomplete combustion results in some carbon monoxide output. It’s nearly impossible to fully isolate the flame to consume all oxygen present. Minimal CO exposure from candles is not severely hazardous. But exposure to cumulative sources in tightly enclosed indoor spaces can potentially be dangerous.

Particulate Matter (PM) – The black soot emitted from paraffin candle flames contains fine particulate matter, along with polyaromatic hydrocarbons and other hydrocarbon fractions. Inhalation of PM and smoke particulates irritates lungs and contributes to asthma, allergies, and other respiratory ailments.

Benzene and Toulene – Paraffin can contain low levels of carcinogenic compounds like benzene and toluene. Though benzene exposure from candle usage falls within recommended exposure limits, it’s still an undesirable emission. The toluene released is more concerning, especially for those already sensitive to indoor air pollution.

Acetaldehyde – This pungent, irritating aldehyde is also a probable human carcinogen. The quantities emitted from candle burning are generally not dangerous alone. But when combined with acetaldehyde from other household products and materials, chronic exposure poses some risk.

Formaldehyde – Traces of formaldehyde are likewise released when paraffin wax combusts. While the levels are low, it can be problematic for those specifically sensitized or allergic to formaldehyde. It also contributes to total indoor formaldehyde that may increase risks.

Nitrogen Oxides (NOx) – Candle flames generate low levels of nitrogen oxides like nitric oxide and nitrogen dioxide. However, candle-sourced NOx is substantially less than gas stoves, ovens, or fireplaces. For most, the nitric oxide released while burning a candle is not a significant health issue. Those with respiratory illnesses may be more reactive.

Scent Chemicals – Finally, any volatile organic compounds (VOCs) used for fragrance in scented candles will vaporize into the air when burned. Some synthetic fragrance chemicals irritate airways or trigger allergies/asthma symptoms in those sensitive.

So in summary, the major emissions from paraffin wax candles include carbon dioxide, water vapor, carbon monoxide, particulate matter, benzene, toluene, acetaldehyde, formaldehyde, nitrogen oxides and any scent chemicals – some harmless, others potentially hazardous.

Minimizing Risks From Paraffin Candle Emissions

While paraffin candles release a mix of gases, the amounts generated through occasional use are generally not acutely toxic. But reducing exposure is smart for better indoor air quality. Consider these tips:

  • Ventilate rooms well when burning candles to allow gases to dissipate.
  • Limit candle burning time to prevent buildup of particulates.
  • Keep wicks trimmed to 1⁄4” to reduce soot production.
  • Avoid old or damaged candles that may release more benzene.
  • Be judicious with heavily scented candles if sensitive to fragrances.
  • Opt for candles made from natural soy, beeswax or vegetable-based waxes when possible.
  • Use candles sparingly and supplement with alternative light sources.
  • Don’t burn candles overnight or unattended.
  • Install carbon monoxide detectors for safety if burning frequently.

With some precautions, paraffin candles can be enjoyed safely. But being aware of the mix of gases released when they burn allows you to minimize risks and make informed choices. Consider shifting to more natural candle varieties made from renewable ingredients whenever possible.


Paraffin wax candles give off carbon dioxide, water vapor, carbon monoxide, particulate matter, benzene, toluene, acetaldehyde, formaldehyde, nitrogen oxides and fragrance chemicals when burned. While paraffin is inexpensive and easy to use in candles, the petroleum-derived wax produces emissions that may degrade indoor air. Exercising caution when burning paraffin candles, ventilating well and using alternative candle waxes can help reduce potential effects on health and air quality. But being mindful of the gases produced provides knowledge to make smart choices.