A 21-year-old Tennessee man died this year while refinishing a tub in an unventilated bathroom. Fumes from methylene chloride, a chemical in the paint stripper he was using, caused carbon monoxide to build up in his blood, and within minutes his heart stopped beating.

Most paint strippers sold in hardware stores and home centers contain methylene chloride, yet few people who use these products understand the danger. These products are known to be responsible for at least 56 accidental-exposure deaths in the US since 1980, and the true death toll is no doubt higher—some methylene chloride fatalities are likely recorded as heart attacks, with no one realizing that this chemical is to blame.

Methylene chloride also is known to cause cancer, though that’s a risk mainly for people who have prolonged exposure to it because they use paint strippers in their professions, not for consumers who use them only occasionally.

What to do: Choose a benzyl ­alcohol–based paint stripper rather than one that contains methylene chloride. It’s safer and does a good job stripping paint, though it does not work as quickly as methylene chloride.

If you do use a methylene chloride paint stripper, do so outdoors or in a large, well-ventilated area, never in a small and/or enclosed space. Do not use methylene chloride to strip the inside of bathtubs, storage tanks or similar objects even if they are not fully enclosed—its fumes are heavier than air, so they can quickly build up to lethal levels inside these, even outdoors.