@thereal_truther @joaquinlife For example, there are approximately 2 million classrooms in the US. Two HEPA filters in every classroom (80% reduction in infections according to Italy study) has a cost of about $1 billion with ongoing maintenance cost of maybe $1/2 billion per year. Not extremely costly IMO.
@例如，thereal_truther@joaquinlife，美国大约有200万间教室。每个教室安装两个HEPA过滤器（根据意大利的研究，感染率降低了80%）的成本约为10亿美元，每年的持续维护成本约为12亿美元。IMO不是非常昂贵。