Conventional and scented candles generate particles of soot and benzene — the same pollutants found in diesel exhaust — according to the EPA. Plus, although lead in candles has been outlawed in the United States, many imported candles still contain lead-stiffened wicks. “Even if these tiny irritants aren't immediately noticeable, repeated low-level exposure can develop into a chemical allergy where even a brief exposure can trigger a rash or coughing fit,” says Rosenman.

How to avoid them: Search out natural, soy-based candles, which burn cleanly and don't use leaded wicks.

Learn about safe air fresheners and how to use essential oils here.

Toxins on your skin: