Sulfur candles, commonly used before DDT, probably still work. They burn sulfur, producing sulfur dioxide, which is the water-free gaseous version of sulfurous

Sulfur candles, commonly used before DDT, probably still work. They burn sulfur, producing sulfur dioxide, which is the water-free gaseous version of sulfurous acid. It's cheap. It wipes out mold spores too. A downside is that stuff like cloth can get bleached. Metals may get discolored.