Researchers claim that the public is likely being exposed to levels of ultrasound that are potentially unsafe due to the absence of sufficient regulations and research.

People are probably being exposed to large amounts of airborne ultrasound without their knowledge, according to researchers at the University of Southampton in the UK. 
The recent study claims such exposure is likely happening in train stations, museums, libraries, stadiums and schools due to the prevalence of public address systems and door sensors, amongst other sources. 
According to a write-up of the findings, areas with an increased likelihood of ultrasound exposure are fertile grounds for increased instances of "...