Investigators are scrutinizing soundproofing foam in a Swiss bar fire that killed 40 people on New Year's Eve. The blaze at Le Constellation bar in Crans-Montana is believed to have started from sparklers or Bengal candles igniting the foam ceiling. Experts suggest the foam, if not flame-retardant treated, can spread fire rapidly and may not meet safety standards, potentially contributing to the rapid spread and high death toll among young partygoers.