[OJFord]

> You also need to monitor the PM2.5 levels to ensure your air purifier is working.

But if you don't have an air purifier, and you're concerned about air quality, surely you want to get one before you start worrying about whether or not it's working?

Or both at the same time, sure, my only point is that if there's already concern I don't see the point in monitoring before or without mitigating.