In Australia, Mike Opelka reports a government warning that blowing out the candles on a birthday cake may adversely affect the health of others who might eat the cake:
No mention of whether this was the result of a tax-funded large-scale study to settle the question of how successfully all those tiny flames kill the germs in the birthday person's breath. I'll say this though. Birthday parties are for families. Family members have already been exposed to the germs in the birthday person's breath.