@PSQ17266 @Kit_Yates_Maths They're legal products that are safe. Cost is modest. Health rules? The rule is: If you want people to be healthy, use them.
Opening windows also, but isn't needed (also less consistent benefit since it depends on wind).
@PSQ17266 @Kit_Yates_Maths 它们是安全的合法产品。成本适中。卫生规则？规则是：如果您希望人们健康，请使用他们。
也可以打开窗户，但不需要（也不太一致的好处，因为它取决于风）。