Its hard to know whats high as I have yet to find any relevant info. Mine is 200-300 seems high only thing I have to go by is others results.
Mine was 450, but surprisingly the Air Purifier I have works well. Left it running all night and it got down to 10.
The PM0.3 as per Plantower is a non calibrated number so it could differ a lot between different production batches.
So it cannot be compared with other monitors easily.
The 0.3 measurement is also cumulative of larger particle sizes and in different units compared to the usual representation of 1/2.5/10 particles.
Mine’s anywhere between 120/dL during great conditions and 11500/dL (during a forest fire next country over.) That’s an outdoor unit.