Have you ever noticed...

• Paraffin wax candles (the most common and cheapest ones) are made from petroleum byproducts. When burned, they can release potentially harmful chemicals like benzene, toluene, and formaldehyde — all of which are known to be toxic at certain exposure levels. Some studies suggest burning a lot of paraffin candles in a poorly ventilated space could contribute to indoor air pollution and respiratory issues over time.
• Scented candles can add another layer of risk. Some fragrances and dyes release volatile organic compounds (VOCs) and even phthalates when burned, which can irritate the lungs, especially for people with asthma or chemical sensitivities.
• Wicks used to be a problem too — some older or cheaply made candles had wicks with lead cores, which release toxic lead fumes. However, the U.S. banned lead in candle wicks in 2003, so it's less of a concern today (but still something to watch out for if you're buying candles from unknown or international sources).
• Soy, coconut, or beeswax candles are much cleaner-burning options. They produce less soot and typically release fewer toxic compounds, especially if they’re made with natural fragrances or essential oils. Beeswax even has a reputation for neutralizing indoor air pollutants, though the science is mixed on that.

Bottom Line:

• Cheap paraffin + synthetic fragrance candles = not great for air quality.
• Natural wax + essential oils + cotton or wood wicks = much safer.