Hi @ClareG,
Thank you for joining the forum and great question!
I actually had a long email conversation with another reader recently about the Airthings monitors and the VOC readings they produce. After about a months’ worth of emails, we concluded that the VOC readings from the monitors were extremely hard to interpret and had limited usefulness. This likely isn’t an issue just with Airthings, however, as VOCs in general are very challenging to monitor. Please see the below thread if you’re curious:
Therefore, it’s very hard to know exactly where the issue may lie here. Is the purifier not performing well? Is the monitor not reporting correctly? Or something else entirely. I don’t mean to worry you further, but I think a good first step would be to get a professional VOC test. The fact that the levels don’t drop when you open the windows surprises me, and this is why I would suggest doing such a test.
I’m not sure which country you’re based in, but in most countries you can find places that send you a test kit. You can then leave these around your house for a week or longer, and send them back. They will then be tested for dangerous VOCs and other gasses, and you will get far more useable results (and also know exactly which VOCs are present).
If you can let me know where you are (just the country is okay!) I can have a look online and see if there are any good options. I also hope something like this might help prevent any anxiety you may be having from the monitor readings. The other reader I was having a conversation with was in the same boat, and the professional test kit provided a lot of peace of mind.
I believe some of them are relatively inexpensive, too!