Yes, candles can certainly cause coughing or trigger other forms of respiratory irritation. Burning a candle involves a combustion process that releases various byproducts into the air, including tiny solid particles and invisible gaseous chemicals. These emissions directly interact with the sensitive tissues of the respiratory system. Understanding the science behind these irritants helps explain why a source of ambiance can sometimes lead to an uncomfortable cough.
Physical Irritation from Particulate Matter and Soot
The most immediate cause of respiratory irritation from a burning candle is the release of physical airborne particles, often visible as soot. This soot is a form of particulate matter (PM) that results from the incomplete burning of the wax and the wick. Combustion that is not perfectly clean produces these carbon-based particles, which are then carried into the surrounding air.
Fine particulates, specifically PM 2.5, are particles with a diameter of 2.5 micrometers or less. These particles are extremely small and can easily bypass the body’s natural defenses, such as the hair in the nasal passages. Once inhaled, PM 2.5 can travel deep into the lungs, settling in the smaller airways and the alveoli, the tiny air sacs responsible for gas exchange.
The physical presence of this foreign matter irritates the delicate lining of the airways, known as the respiratory mucosa. In response, the body attempts to expel the irritants through the coughing reflex. Factors that increase soot production, such as an overly long wick or a candle burning in a drafty location, increase the concentration of these irritating particles. An untrimmed wick promotes incomplete combustion and excessive sooting.
Chemical Exposure from Fragrances and Wax Composition
Beyond the physical particles, candles can also release gaseous irritants that are distinct from the solid soot. When a candle is heated, especially those containing synthetic additives, it releases Volatile Organic Compounds (VOCs) into the air. VOCs are chemicals that easily vaporize at room temperature, and they are a primary source of chemical exposure from many candles.
The type of wax used is a major factor in VOC release, with paraffin wax being a common source of concern. Paraffin is a petroleum byproduct, and when burned, it can release toxic compounds such as benzene, toluene, and formaldehyde. These chemicals are known to irritate the respiratory tract, eyes, and throat, sometimes leading to symptoms like a cough, dizziness, or headaches.
Scented candles often contain synthetic fragrances composed of various VOCs. For individuals with existing respiratory sensitivities like asthma or allergies, inhaling these compounds can exacerbate their condition, triggering inflammation and leading to airway constriction and a persistent cough. The chemical irritation acts directly on the airway nerves, prompting the coughing reflex.
Protecting Your Respiratory Health While Burning Candles
Mitigating the respiratory risks associated with burning candles involves a combination of good maintenance habits and informed material choices. Proper ventilation is one of the most effective strategies for reducing the concentration of both particulate matter and VOCs in the air. Burning candles in a room with an open window or using an exhaust fan helps to disperse the pollutants, preventing them from accumulating to irritating levels.
Routine maintenance of the candle itself significantly impacts the cleanliness of the burn. Always trimming the wick to approximately one-quarter inch before each use is a simple action that promotes a smaller, steadier flame and minimizes the production of black soot. Limiting the burn time to a few hours at a time also prevents the wax pool from overheating, which can lead to increased emissions.
When selecting candles, choosing alternative wax types can reduce the number of pollutants released. Waxes derived from natural sources, such as soy, beeswax, or coconut wax, generally burn cleaner and produce less soot and fewer VOCs compared to petroleum-based paraffin. Additionally, opting for candles scented with natural essential oils rather than synthetic fragrances can reduce chemical exposure.
Flameless Alternatives
For those who are highly sensitive to any form of smoke or fragrance, flameless alternatives like essential oil diffusers are a safe option. These alternatives provide ambiance without the combustion byproducts.