@cheesemonkeysf @hkfinan @GavinNewsom https://envomask.com/
Replacable filters cost $2 each but don't need to be replaced until it becomes hard to breath. Likely a long time in a classroom with generally clean air.
@cheesemonkeysf@hkfinan@GavinNewsomhttps://envomask.com/
可更换的过滤器每个售价2美元，但在呼吸困难之前不需要更换。可能在空气清洁的教室里呆了很长时间。