@PSQ17266 @Kit_Yates_Maths Windows open works to improve ventilation, sometimes. Filtering works regardless.
Yes VERY modest cost vs people being sick. One or two extra sick days per year pays for itself, and the number will be much larger than that considering teachers, parents, and missed learning.
@PSQ17266 @Kit_Yates_Maths 有时打开窗户可以改善通风。无论如何过滤都有效。
是的，与生病的人相比，成本非常低。每年一到两个额外的病假是值得的，而且这个数字会比考虑到老师、家长和错过的学习的数字要大得多。