In an alert notice issued by federal officials, the two agencies said they had opened the probe after one unidentified mine reported a malfunction involving four of its M-20s.
The units had been produced in 2008.
“As is usual practice, MSHA and NIOSH are investigating further,” the two said.
Federal officials are also contacting US mine operators to ensure the required tests of SCSRs are being conducted.
“[We want to] ensure that any defect, performance problem, or malfunction of an SCSR is reported to MSHA as required,” the agency said.
ILN’s requests for comment from MSHA and Wisconsin-based Ocenco were not immediately returned.
The SCSR maker’s two primary products are the M-20.2, a belt-worn unit designed for 20 minutes of breathable air and the EBA 6.5, often stored in caches which allows for more than 90 minutes of oxygen.
