VOC levels - any idea

Hello,
I have zwave device: EUROtronic Air Quality Sensor EUR_AIRQUALITY

which gave me the following measurements… on VOCs

Not sure how standardized and accurate device is … but according the site

IEQ | TSI
OCs that is lower than 0.5 mg/m3 can be considered acceptable.

the VOCs reading are in my case far above 0.5mg/m3?, as i am getting results around >1ppm which equals 3.229 mg/m3 which is Above 0.5mg/m3

The response from the manufacturer is:
We say hygienically safe is <1 mg/m³ – below 150 bis 400 ppb, hygienically conspicuous, 1 bis 3 mg/m³ – 150 bis 1300 ppb and hygienically unacceptable above 1500 until 4000 ppb.

but frankly i do not understand it at all.

Thank you!