How Do Candles Affect Your Indoor Air Quality?

Candles are a popular way to create a pleasant ambiance and add fragrance to a home. However, it is logical to question how burning something indoors might affect the air we breathe. Understanding the relationship between candles and indoor air quality can help people make more informed choices about their use.

What Candles Release into the Air

When a candle burns, it releases more than just light and heat; it also emits a variety of microscopic substances into the air. The process of combustion releases volatile organic compounds (VOCs), which are chemicals that can easily become gases at room temperature. Some common VOCs associated with candle emissions include formaldehyde, acetaldehyde, and benzene. These substances can become trapped and concentrated within enclosed indoor spaces.

Another significant emission from burning candles is particulate matter, often visible as soot. These are tiny, unburned carbon particles that become airborne. The smallest of these particles, known as fine or ultrafine particles, can be a particular concern for indoor air quality. Due to their small size, these particles can remain suspended in the air for extended periods and may be inhaled.

How Candle Composition Affects Emissions

The materials used to make a candle can influence the type and quantity of emissions produced. A primary factor is the wax. Paraffin wax, a byproduct of petroleum refining, is a common candle wax. Studies have indicated that burning paraffin wax can release certain VOCs, contributing to indoor air pollution. In contrast, waxes from natural sources such as soy, beeswax, or coconut are considered to burn cleaner.

Fragrance is another component that affects a candle’s emissions. Whether derived from synthetic fragrance oils or natural essential oils, these aromatic compounds are released into the air as the wax melts. The addition of fragrance oils can sometimes lead to more soot production than is seen with unscented candles. The chemical composition of the fragrance itself contributes to the profile of VOCs released.

The wick also has a role in how a candle burns and what it releases. An appropriate wick, made of cotton or wood, will burn evenly and help to minimize soot production. Wicks that contain a metal core, particularly lead, were once a concern, but lead-core wicks have been banned in the United States due to health risks.

Safe Candle Burning Practices

To minimize the impact of candles on indoor air quality, several best practices can be followed. One of the most effective techniques is to trim the wick to about one-quarter of an inch before each use. A shorter wick creates a smaller, more controlled flame, which reduces the amount of soot produced. A long, untrimmed wick is more likely to create a tall, flickering flame that generates significantly more smoke and soot.

The environment where a candle is burned also matters. Placing a candle in a draft-free area helps the flame burn steadily, preventing uneven melting and reducing smoke. It is also advisable to limit the duration of burning, with a common recommendation being no more than four hours at a time. This limits the total accumulation of pollutants in the room.

Ensuring proper ventilation is another direct way to mitigate the buildup of emissions. Opening a window or using an air purifier can help to circulate fresh air and remove airborne particles and VOCs. Finally, a burning candle should never be left unattended, as this poses a significant fire hazard.

Alternatives for Home Fragrance

For those who wish to scent their homes without a flame, several alternatives are available. Essential oil diffusers, for example, use water and ultrasonic vibrations to create a fine mist of water and essential oils. This method disperses fragrance without combustion, thereby avoiding the creation of soot and other burning byproducts.

Wax warmers are another option that provides a similar experience to a scented candle. These devices use a low-wattage light bulb or a warming plate to melt scented wax melts. Because the wax is melted below its combustion point, it releases fragrance without producing a flame or smoke. Other non-combustion methods include reed diffusers, which use reeds to draw up scented oil, and potpourri, a mixture of dried, scented plant materials.