Hi @Anru56, 

From my own experience, I know the sensors on Dyson purifiers can pick up the tiny droplets of water vapour in the air when a humidifier is running, and may interpret these as as a ‘pollution event’. You’ll be able to see this shown as a poor air quality readout on the LCD screen, and within the MyDyson app. On Auto mode, your purifier may also increase it’s airflow speed as a result. This is normal, but you might prefer to switch your purifier to manual control while your humidifier is running, to make sure the airflow speed suits your needs.

Hope this helps,

Jack 

An unrelated use case but the same result. I think the advice on this post and the reply by @Stuart might also help. https://community.dyson.com/general-discussion-95/using-a-purifier-with-essential-oils-672

1. Separating the machine and finding the happy medium in your home where the humidifierdoes not directly affect your Purifier.
2. Check with the Manufacture of the Humidifier on their recommendations on using it in conjunction with the Purifier.
3. Instead of using Auto mode, try the machine on a manual setting. Whilst the Air Quality may spike, if you are happy to accept this, the machine will not auto adjust the fan speed to remove the detected mineral from the air. 

Jay