Evidence consistently shows that ultrasonic humidifiers disperse dissolved minerals from water into the air, significantly elevating measurable indoor PM2.5 levels.
The claim is specific and testable regarding indoor air quality physics. Multiple retrieved papers explicitly study ultrasonic humidifiers, finding that they aerosolize water minerals that form particulate matter (often called white dust) and significantly raise indoor PM2.5 levels when using tap water. Papers [0], [2], [5], [6], and [7] are tangential, leaving [1], [3], and [4] strongly supporting the claim.