For a manufacturer it's not as cut-and-dry. The damage caused is a factor of the level (dB) received combined with the length of exposure. Assumptions will have to be made as to how far away the user will be from the device and how long they can reasonably be expected to be exposed.

For example, if you assume that someone will be under it for 8 hours (an employee during a work day), the OSHA approved exposure is 90dB, which will likely not be annoying enough to serve its purpose.

That doesn't seem physically possible since it's based on sound pressure waves.. From your link, mk1 uses 85 db set volume; mk2 uses ambient noise level + 5db.