Indoor air pollution is a common concern, given the fact that our houses are more tightly sealed than ever. The insulation, double-paned windows, and weather stripping that keep the elements out keep pollutants in, including the emissions from paraffin candles, which are produced from petroleum.

Paraffin wax, particularly the scented variety, is more likely to produce soot than is wax made by bees or from soy or vegetable oil. All three of these waxes burn much more cleanly, but they are a bit more difficult to find.

In rare instances, paraffin candles have wicks with lead cores. According to the Environmental Protection Agency, burning candles with lead-core wicks can push airborne concentrations of lead to unsafe levels. The use of lead in wicks was discontinued in this country in 1974, but some foreign manufacturers continue the practice. To determine if a metal-core wick is made with lead (other common materials are zinc and tin, which are safe), rub an unburned wick against paper. If it leaves a pencil-like mark, it contains lead and should be discarded.

One final safety tip: Never, ever leave a burning candle unattended.